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| Breast Cancer Classification and external resources |
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| Mammogram showing breast cancer (indicated by arrow) | |
| ICD-10 | C50. |
| ICD-9 | 174-175 |
| OMIM | 114480 |
| DiseasesDB | 1598 |
| MedlinePlus | 000913 |
| eMedicine | med/2808 |
| MeSH | D001943 |
Breast cancer is a cancer that starts in the cells of the breast in men and women.[1] Worldwide, breast cancer is the second most common type of cancer after lung cancer (10.4% of all cancer incidence, both sexes counted)[2] and the fifth most common cause of cancer death.[3] Worldwide, breast cancer is by far the most common cancer amongst women, with an incidence rate more than twice that of colorectal cancer and cervical cancer and about three times that of lung cancer. However breast cancer mortality worldwide is just 25% greater than that of lung cancer in women.[2] In 2005, breast cancer caused 502,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths).[3] The number of cases worldwide has significantly increased since the 1970s, a phenomenon partly blamed on modern lifestyles in the Western world.[4][5]
The incidence of breast cancer varies greatly around the world, being lower in less-developed countries and greatest in the more-developed countries. In the twelve world regions, the annual age-standardized incidence rates per 100,000 women are as follows: in Eastern Asia, 18; South Central Asia, 22; sub-Saharan Africa, 22; South-Eastern Asia, 26; North Africa and Western Asia, 28; South and Central America, 42; Eastern Europe, 49; Southern Europe, 56; Northern Europe, 73; Oceania, 74; Western Europe, 78; and in North America, 90.[6]
Women in the United States have the highest incidence rates of breast cancer in the world; 141 among white women and 122 among African American women.[7][8] Among women in the US, breast cancer is the most common cancer and the second-most common cause of cancer death (after lung cancer).[8] Women in the US have a 1 in 8 (12.5%) lifetime chance of developing invasive breast cancer and a 1 in 35 (3%) chance of breast cancer causing their death.[8] In 2007, breast cancer was expected to cause 40,910 deaths in the US (7% of cancer deaths; almost 2% of all deaths).[9]
In the US, both incidence and death rates for breast cancer have been declining in the last few years.[10][9] Nevertheless, a US study conducted in 2005 by the Society for Women's Health Research indicated that breast cancer remains the most feared disease,[11] even though heart disease is a much more common cause of death among women.[12]
Because the breast is composed of identical tissues in males and females, breast cancer also occurs in males.[13][14] Incidences of breast cancer in men are approximately 100 times less common than in women, but men with breast cancer are considered to have the same statistical survival rates as women.[15]
Classification
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It has been suggested that this section be split into a new article. () |
Breast cancers are described along four different classification schemes, or groups, each based on different criteria and serving a different purpose:
- Pathology - A pathologist will categorize each tumor based on its histological (microscopic anatomy) appearance and other criteria. The most common pathologic types of breast cancer are invasive ductal carcinoma, malignant cancer in the breast's ducts, and invasive lobular carcinoma, malignant cancer in the breast's lobules.
- Grade of tumor - The histological grade of a tumor is determined by a pathologist under a microscope. A well-differentiated (low grade) tumor resembles normal tissue. A poorly differentiated (high grade) tumor is composed of disorganized cells and, therefore, does not look like normal tissue. Moderately differentiated (intermediate grade) tumors are somewhere in between.
- Protein & gene expression status - Currently, all breast cancers should be tested for expression, or detectable effect, of the estrogen receptor (ER), progesterone receptor (PR) and HER2/neu proteins. These tests are usually done by immunohistochemistry and are presented in a pathologist's report. The profile of expression of a given tumor helps predict its prognosis, or outlook, and helps an oncologist choose the most appropriate treatment. More genes and/or proteins may be tested in the future.
- Stage of a tumor - The currently accepted staging scheme for breast cancer is the TNM classification.
There are five tumor classification values (Tis, T1, T2, T3 or T4) which depend on the presence or absence of invasive cancer, the dimensions of the invasive cancer, and the presence or absence of invasion outside of the breast (e.g. to the skin of the breast, to the muscle or to the rib cage underneath):
- Tx - Primary tumor cannot be assessed.
- T0 - No evidence of primary tumor.
- Tis - Carcinoma in situ.
- Tis(DCIS) - Intraductal Carcinoma in situ.
- Tis(LCIS) - Lobular Carcinoma in situ.
- Tis(Paget's) - Paget's disease of the nipple with no tumor.
- T1 - Tumor 2cm or less in its greatest dimension.
- T1mic - Microinvasion 0.1cm or less in greatest dimension.
- T1a - Tumor more than 0.1cm but not more than 0.5cm in its greatest dimension.
- T1b - Tumor more than 0.5cm but not more than 1.0cm in its greatest dimension.
- T1c - Tumor more than 1.0cm but not more than 2.0cm in its greatest dimension.
- T2 - Tumor more than 2.0cm but not more than 5.0cm in its greatest dimension.
- T3 - Tumor more than 5cm in its greatest dimension.
- T4 - Tumor of any size with direct extension to (a) chest wall or (b) skin as described below:
- T4a - Extension to chest wall.
- T4b - Edema (including peau d'orange) or ulceration of the breast skin, or satellite skin nodules confined to the same breast.
- T4c - Both T4a and T4b.
- T4d - Inflammatory breast cancer.
Lymph Node - There are four lymph node classification values (N0, N1, N2 or N3) which depend on the number, size and location of breast cancer cell deposits in lymph nodes.
- Nx - regional lymph nodes cannot be assessed. Perhaps due to previous removal.
- N0 - no regional lymph node metastasis.
- N1 - metastasis to movable regional axillary lymph nodes on the same side as the affected breast.
- N2 - metastasis to fixed regional axillary lymph nodes, or metastasis to the internal mammary lymph nodes, on the same side as the affected breast.
- N3 - metastasis to supraclavicular lymph nodes or infraclavicular lymph nodes or metastasis to the internal mammary lymph nodes with metastasis to the axillary lymph nodes.
Metastases - There are two metastatic classification values (M0 or M1) which depend on the presence or absence of breast cancer cells in locations other than the breast and lymph nodes (so-called distant metastases, e.g. to bone, brain, lung).
Pathologic types
Note: The following table includes benign tumours (non cancers) as well as malignant tumours (cancers)
The latest (2003) World Health Organization (WHO) classification of tumors of the breast[16] recommends the following pathological types:
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Invasive breast carcinomas
Mesenchymal tumors (including sarcoma)
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Precursor lesions
Benign epithelial lesions
Myoepithelial lesions
Fibroepithelial tumours
Tumours of the nipple
Malignant lymphoma Metastatic tumours Tumours of the male breast
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The classifications above show that breast cancer is usually, but not always, classified by its histological appearance. Rare variants are defined on the basis of physical exam findings. For example, Inflammatory breast cancer (IBC), a form of ductal carcinoma or malignant cancer in the ducts, is distinguished from other carcinomas by the inflamed appearance of the affected breast.[17] In the future, some pathologic classifications may be changed. For example, a subset of ductal carcinomas may be re-named basal-like carcinoma (part of the "triple-negative" tumors).citation needed
Signs and symptoms
The first symptom, or subjective sign, of breast cancer is typically a lump that feels different than the surrounding breast tissue. According to the Merck Manual, greater than 80% of breast cancer cases are discovered as a lump by the woman herself.[18] According to the American Cancer Society (ACS), the first medical sign, or objective indication of breast cancer as detected by a physician, is discovered by mammogram.[9] Lumps found in lymph nodes located in the armpits[18] and/or collarbonecitation needed can also indicate breast cancer.
Indications of breast cancer other than a lump may include changes in breast size or shape, skin dimpling, nipple inversion, or spontaneous single-nipple discharge. Pain is an unreliable tool in determining the presence of breast cancer, but may be indicative of other breast-related health issues such as mastodynia.[9][18][19]
When breast cancer cells invade the dermal lymphatics, small lymph vessels in the skin of the breast, its presentation can resemble skin inflammation and thus is known as inflammatory breast cancer (IBC). Symptoms of inflammatory breast cancer include pain, swelling, warmth and redness throughout the breast, as well as an orange peel texture to the skin referred to as peau d'orange.[18]
Another reported symptom complex of breast cancer is Paget's disease of the breast. This syndrome presents as eczematoid skin changes such as redness and mild flaking of the nipple skin. As Paget's advances, symptoms may include tingling, itching, increased sensitivity, burning, and pain. There may also be discharge from the nipple. Approximately half of women diagnosed with Paget's also have a lump in the breast.[20]
Occasionally, breast cancer presents as metastatic disease, that is, cancer that has spread beyond the original organ. Metastatic breast cancer will cause symptoms that depend on the location of metastasis. More common sites of metastasis include bone, liver, lung and brain. Unexplained weight loss can occasionally herald an occult breast cancer, as can symptoms of fevers or chills. Bone or joint pains can sometimes be manifestations of metastatic breast cancer, as can jaundice or neurological symptoms. These symptoms are "non-specific," meaning they can also be manifestations of many other illnesses.[21]
Most symptoms of breast disorder do not turn out to represent underlying breast cancer. Benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms. The appearance of a new symptom should be taken seriously by both patients and their doctors, because of the possibility of an underlying breast cancer at almost any age.[22]
Epidemiology and etiology
Epidemiological risk factors for a disease can provide important clues as to the etiology, or cause, of a disease. The first case-controlled study on breast cancer epidemiology was done by Janet Lane-Claypon, who published a comparative study in 1926 of 500 breast cancer cases and 500 control patients of the same background and lifestyle for the British Ministry of Health.[23]verification needed[24]
Today, breast cancer, like other forms of cancer, is considered to be the final outcome of multiple environmental and hereditary factors. Some of these factors include:
- Lesions to DNA such as genetic mutations. Mutations that can lead to breast cancer have been experimentally linked to estrogen exposure.[25] Beyond the contribution of estrogen, research has implicated viral oncogenesis and the contribution of ionizing radiation in causing genetic mutations.citation needed
- Failure of immune surveillance, a theory in which the immune system removes malignant cells throughout one's life.[26]
- Abnormal growth factor signaling in the interaction between stromal cells and epithelial cells can facilitate malignant cell growth. For example, tumors can induce blood vessel growth (angiogenesis) by secreting various growth factors further facilitating cancer growth.citation needed
- Inherited defects in DNA repair genes, such as BRCA1, BRCA2[27] and p53.citation needed
Although many epidemiological risk factors have been identified, the cause of any individual breast cancer is often unknowable. In other words, epidemiological research informs the patterns of breast cancer incidence across certain populations, but not in a given individual. The primary risk factors that have been identified are sex,[28] age,[29] childbearing, hormones,[30] a high-fat diet,[31] alcohol intake,[32][33] obesity,[34] and environmental factors such as tobacco use, radiation[27] and shiftwork.[35]
No etiology is known for 95% of breast cancer cases, while approximately 5% of new breast cancers are attributable to hereditary syndromes.[36] In particular, carriers of the breast cancer susceptibility genes, BRCA1 and BRCA2, are at a 30-40% increased risk for breast and ovarian cancer, depending on in which portion of the protein the mutation occurs.[37]
Prevention
Lower age of first childbirth (less than 24 years maternal age), having more children (about 7% lowered risk per child), and breastfeeding (4% per breastfeeding year, with an average relative risk around 0.7[38][39]) have all been correlated to lowered breast cancer risk in large studies.[40] In addition, exercising three times a week for one hour each has been found to lower breast cancer by up to 40%.citation needed
Phytoestrogens and soy
Phytoestrogens such as found in soybeans have been extensively studied in animal and human in-vitro and epidemiological studies. The literature support the following conclusions:
- Plant estrogen intake, such as from soy products, in early adolescence may protect against breast cancer later in life.[41]
- Plant estrogen intake later in life is not likely to influence breast cancer incidence either positively or negatively.[42]
Folic acid (folate)
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The factual accuracy of this article is disputed. Please see the relevant discussion on the talk page. (March 2008) |
Studies have found that "folate intake counteracts breast cancer risk associated with alcohol consumption"[43] and "women who drink alcohol and have a high folate intake are not at increased risk of cancer."[44][45][46] A prospective study of over 17,000 women found that those who consume 40 grams of alcohol (about 3-4 drinks) per day have a higher risk of breast cancer. However, in women who take 200 micrograms of folate (folic acid or Vitamin B9) every day, the risk of breast cancer drops below that of alcohol abstainers.[47]
Folate is involved in the synthesis, repair, and functioning of DNA, the body’s genetic map, and a deficiency of folate may result in damage to DNA that may lead to cancer.[48] In addition to breast cancer, studies have also associated diets low in folate with increased risk of pancreatic, and colon cancer.[49][50]
Foods rich in folate include citrus fruits, citrus juices, dark green leafy vegetables (such as spinach), dried beans, and peas. Vitamin B9 can also be taken in a multivitamin pill.
Avoiding exposure to secondhand tobacco smoke
Breathing secondhand smoke increases breast cancer risk by 70% in younger, primarily pre-menopausal women. The California Environmental Protection Agency has concluded that passive smoking causes breast cancer[51] and the US Surgeon General[52] has concluded that the evidence is "suggestive," one step below causal. There is some evidence that exposure to tobacco smoke is most problematic between puberty and first childbirth. The reason that breast tissue appears most sensitive to chemical carcinogens in this phase is that breast cells are not fully differentiated until lactation.[53]
Oophorectomy and mastectomy
Prophylactic oophorectomy (removal of ovaries), in high-risk individuals, when child-bearing is complete, reduces the risk of developing breast cancer by 60%, as well as reducing the risk of developing ovarian cancer by 96%.[54]
Medications
Hormonal therapy has been used for chemoprevention in individuals at high risk for breast cancer. In 2002, a clinical practice guideline by the US Preventive Services Task Force (USPSTF) recommended that "clinicians discuss chemoprevention with women at high risk for breast cancer and at low risk for adverse effects of chemoprevention" with a grade B recommendation.[55]verification needed[56][57]
Selective estrogen receptor modulators (SERMs)
The guidelinesclarify were based on studies of SERMs from the MORE, BCPT P-1, and Italian trials. In the MORE trial, the relative risk reduction for raloxifene was 76%.[58] The P-1 preventative study demonstrated that tamoxifen can prevent breast cancer in high-risk individuals. The relative risk reduction was up to 50% of new breast cancers, though the cancers prevented were more likely estrogen-receptor positive (this is analogous to the effect of finasteride on the prevention of prostate cancer, in which only low-grade prostate cancers were prevented).[59][60] The Italian trial showed benefit from tamoxifen.[61]
Additional randomized controlled trials have been published since the guidelines. The IBIS trial found benefit from tamoxifen.[62] In 2006, the NSABP STAR trial demonstrated that raloxifene had equal efficacy in preventing breast cancer compared with tamoxifen, but that there were fewer side effects with raloxifene.[63] The RUTH Trial concluded that "benefits of raloxifene in reducing the risks of invasive breast cancer and vertebral fracture should be weighed against the increased risks of venous thromboembolism and fatal stroke".[64] On September 14, 2007, the US Food and Drug Administration approved raloxifene (Evista) to prevent invasive breast cancer in postmenopausal women.[65]
Screening
Breast cancer screening is an attempt to find unsuspected cancers. The most common screening methods are self and clinical breast exams, x-ray mammography, and breast Magnetic resonance imaging (MRI)
X-ray mammography
Mammography is still the modality of choice for screening of early breast cancer, since it is relatively fast, reasonably accurate, and widely available in developed countries.
Due to the high incidence of breast cancer among older women, screening is now recommended in many countries. Recommended screening methods include breast self-examination and mammography. Mammography has been estimated to reduce breast cancer-related mortality by 20-30%.[66] Routine (annual) mammography of women older than age 40 or 50 is recommended by numerous organizations as a screening method to diagnose early breast cancer and has demonstrated a protective effect in multiple clinical trials.[67] The evidence in favor of mammographic screening comes from eight randomized clinical trials from the 1960s through 1980s. Many of these trials have been criticised for methodological errors, and the results were summarized in a review article published in 1993.[68]
Improvements in mortality due to screening are hard to measure; similar difficulty exists in measuring the impact of Pap smear testing on cervical cancer, though worldwide, the impact of that test is likely enormous. Nationwide mortality due to cancer before and after the institution of a screening test is a surrogate indicator about the effectiveness of screening, and results of mammography are favorable.
The U.S. National Cancer Institute recommends screening mammography every one to two years beginning at age 40.[69] In the UK, women are invited for screening once every three years beginning at age 50. Women with one or more first-degree relatives (mother, sister, daughter) with premenopausal breast cancer should begin screening at an earlier age. It is usually suggested to start screening at an age that is 10 years less than the age at which the relative was diagnosed with breast cancer.
A clinical practice guideline by the US Preventive Services Task Force recommended "screening mammography, with or without clinical breast examination (CBE), every 1 to 2 years for women aged 40 and older."[70] The Task Force gave a grade B recommendation.[55]verification needed
In 2005, 67.9% of all U.S. women age 40–64 had a mammogram in the past two years (74.5% of women with private health insurance, 56.1% of women with Medicaid insurance, 38.1% of currently uninsured women, and 32.9% of women uninsured for > 12 months).[71]
Criticisms of screening mammography
Several scientific groups however have expressed concern about the public's perceptions of the benefits of breast screening.[72] In 2001, a controversial review published in The Lancet claimed that "there is no reliable evidence that screening for breast cancer reduces mortality".[73][74]The Cochrane Collaboration concluded, "for every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily. It is thus not clear whether screening does more good than harm."[75]
False positives are a major problem of mammographic breast cancer screening. Data reported in the UK Million Woman Study indicates that if 134 mammograms are performed, 20 women will be called back for suspicious findings, and four biopsies will be necessary, to diagnose one cancer. Recall rates are higher in the U.S. than in the UK.[76] The contribution of mammography to the early diagnosis of cancer is controversial, and for those found with benign lesions, mammography can create a high psychological and financial cost.
Mammography in women less than 50 years old
Part of the difficulty in interpreting mammograms in younger women stems from the problem of breast density. Radiographically, a dense breast has a preponderance of glandular tissue, and younger age or estrogen hormone replacement therapy contribute to mammographic breast density. After menopause, the breast glandular tissue gradually is replaced by fatty tissue, making mammographic interpretation much more accurate. Some authors speculate that part of the contribution of estrogen hormone replacement therapy to breast cancer mortality arises from the issue of increased mammographic breast density. Breast density is an independent adverse prognostic factor on breast cancer prognosis.
A systematic review by the American College of Physicians concluded "Although few women 50 years of age or older have risks from mammography that outweigh the benefits, the evidence suggests that more women 40 to 49 years of age have such risks".[77].
A report released November 27, 2007 by the Journal of the National Cancer Institute showed that the formula doctors use to calculate a woman's risk of breast cancer underestimates the danger for black women most of the time and especially for those age 50 and older — the age when they are most likely to benefit from screening tests and protective drugs, according to the first major reassessment of the widely used tool.[78]
Enhancements to mammography
CAD is especially established in US and the Netherlands. It is used in addition to the human evaluation of the diagnostician.
Breast MRI
Magnetic resonance imaging (MRI) has been shown to detect cancers not visible on mammograms, but has long been regarded to have disadvantages. For example, although it is 27-36% more sensitive, it is less specific than mammography.[79] As a result, MRI studies will have more false positives (up to 5%), which may have undesirable financial and psychological costs. It is also a relatively expensive procedure, and one which requires the intravenous injection of a chemical agent (from which there are side effects, potentially serious in a small number of people) to be effective. Proposed indications for using MRI for screening include:[80]
- Strong family history of breast cancer
- Patients with BRCA-1 or BRCA-2 tumour suppressor gene mutations
- Evaluation of women with breast implants
- History of previous lumpectomy or breast biopsy surgeries
- Axillary metastasis with an unknown primary tumor
- Very dense or scarred breast tissue
However, two studies published in 2007 demonstrated the strengths of MRI-based screening:
- In March 2007, an article published in the New England Journal of Medicine demonstrated that in 3.1% of patients with breast cancer, whose contralateral breast was clinically and mammographically tumor-free, MRI could detect breast cancer. Sensitivity for detection of breast cancer in this study was 91%, specificity 88%.[81]
- In August 2007, an article published in The Lancet compared MRI breast cancer screening to conventional mammographic screening in 7,319 women. MRI screening was highly more sensitive (97% in the MRI group vs. 56% in the mammography group) in recognizing early high-grade Ductal Carcinoma in situ (DCIS), the most important precursor of invasive carcinoma. Despite the high sensitivity, MRI screening had a positive predictive value of 52%, which is totally accepted for cancer screening tests.[82] The author of a comment published in the same issue of The Lancet concludes that "MRI outperforms mammography in tumour detection and diagnosis."[83]
Breast self-exam
Breast self-examination (BSE) was widely discussed in the 1990s as a useful modality for detecting breast cancer at an earlier stage of presentation. A large clinical trial in China reduced enthusiasm for breast self-exam. In the trial, reported in the Journal of the National Cancer Institute first in 1997 and updated in 2002, 132,979 female Chinese factory workers were taught by nurses at their factories to perform monthly breast self-exam, while 133,085 other workers were not taught self-exam. The women taught self-exam tended to detect more breast nodules, but their breast cancer mortality rate was no different from that of men and women in the control group. In other words, men and women taught breast self-exam were mostly likely to detect benign breast disease, but were just as likely to die of breast cancer.[84] In 2003, the American Cancer Society relegated structured BSE to an 'optional' method of detecting breast cancer, citing self awareness as more important than structured self exams based on recent research.[27]
Genetic testing
A clinical practice guideline by the US Preventive Services Task Force :[70]
- "recommends against routine referral for genetic counseling or routine breast cancer susceptibility gene (BRCA) testing for men and women whose family history is not associated with an increased risk for deleterious mutations in breast cancer susceptibility gene 1 (BRCA1) or breast cancer susceptibility gene 2 (BRCA2)" The Task Force gave a grade D recommendation.[55]verification needed
- "recommends that women whose family history is associated with an increased risk for deleterious mutations in BRCA1 or BRCA2 genes be referred for genetic counseling and evaluation for BRCA testing." The Task Force gave a grade B recommendation.[55]verification needed
The Task Force noted that about 2% of women have family histories that indicate increased risk as defined by:
- For non–Ashkenazi Jewish women, any of the following:
- "2 first-degree relatives with breast cancer, 1 of whom received the diagnosis at age 50 years or younger"
- "3 or more first- or second-degree relatives with breast cancer regardless of age at diagnosis"
- "both breast and ovarian cancer among first- and second- degree relatives"
- "a first-degree relative with bilateral breast cancer"
- "a combination of 2 or more first- or second-degree relatives with ovarian cancer regardless of age at diagnosis"
- "a first- or second-degree relative with both breast and ovarian cancer at any age"
- "a history of breast cancer in a male relative."
- "For women of Ashkenazi Jewish heritage, an increased-risk family history includes any first-degree relative (or 2 second-degree relatives on the same side of the family) with breast or ovarian cancer."
Diagnosis
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This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. (October 2007) |
Breast cancer is diagnosed by the examination of surgically removed breast tissue. A number of procedures can obtain tissue or cells prior to definitive treatment for histological or cytological examination. Such procedures include fine-needle aspiration, nipple aspirates, ductal lavage, core needle biopsy, and local surgical excision. These diagnostic steps, when coupled with radiographic imaging, are usually accurate in diagnosing a breast lesion as cancer. Occasionally, pre-surgical procedures such as fine needle aspirate may not yield enough tissue to make a diagnosis, or may miss the cancer entirely. Imaging tests are sometimes used to detect metastasis and include chest X-ray, bone scan, Cat scan, MRI, and PET scanning. While imaging studies are useful in determining the presence of metastatic disease, they are not in and of themselves diagnostic of cancer. Only microscopic evaluation of a biopsy specimen can yield a cancer diagnosis. Ca 15.3 (carbohydrate antigen 15.3, epithelial mucin) is a tumor marker determined in blood which can be used to follow disease activity over time after definitive treatment. Blood tumor marker testing is not routinely performed for the screening of breast cancer, and has poor performance characteristics for this purpose.
Staging
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It has been suggested that this section be split into a new article entitled Breast cancer staging. () |
Breast cancer is staged according to the TNM system, updated in the AJCC Staging Manual, now on its sixth edition. Prognosis is closely linked to results of staging, and staging is also used to allocate patients to treatments both in clinical trials and clinical practice. The information for staging is as follows:
TX: Primary tumor cannot be assessed. T0: No evidence of tumor. Tis: Carcinoma in situ, no invasion T1: Tumor is 2 cm or less T2: Tumor is more than 2 cm but not more than 5 cm T3: Tumor is more than 5 cm T4: Tumor of any size growing into the chest wall or skin, or inflammatory breast cancer
NX: Nearby lymph nodes cannot be assessed N0: Cancer has not spread to regional lymph nodes. N1: Cancer has spread to 1 to 3 axillary or one internal mammary lymph node N2: Cancer has spread to 4 to 9 axillary lymph nodes or multiple internal mammary lymph nodes N3: One of the following applies:
Cancer has spread to 10 or more axillary lymph nodes, or Cancer has spread to the lymph nodes under the clavicle (collar bone), or Cancer has spread to the lymph nodes above the clavicle, or Cancer involves axillary lymph nodes and has enlarged the internal mammary lymph nodes, or Cancer involves 4 or more axillary lymph nodes, and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy.
MX: Presence of distant spread (metastasis) cannot be assessed. M0: No distant spread. M1: Spread to distant organs, not including the supraclavicular lymph node, has occurred
Summary of stages:
- Stage 0 - Carcinoma in situ
- Stage I - Tumor (T) does not involve axillary lymph nodes (N).
- Stage IIA – T 2-5 cm, N negative, or T <2 cm and N positive.
- Stage IIB – T > 5 cm, N negative, or T 2-5 cm and N positive (< 4 axillary nodes).
- Stage IIIA – T > 5 cm, N positive, or T 2-5 cm with 4 or more axillary nodes
- Stage IIIB – T has penetrated chest wall or skin, and may have spread to < 10 axillary N
- Stage IIIC – T has > 10 axillary N, 1 or more supraclavicular or infraclavicular N, or internal mammary N.
- Stage IV – Distant metastasis (M)
Approximately 90% of new breast cancer cases in the US will be classified as a "Stage I" cases, due to early detection and prevention techniques. Early-stage treatment options are different from late-stage options.[85] Breast lesions are examined for certain markers, notably sex steroid hormone receptors. About two thirds of postmenopausal breast cancers are estrogen receptor positive (ER+) and progesterone receptor positive (PR+).[86] Receptor status modifies the treatment as, for instance, only ER-positive tumors, not ER-negative tumors, are sensitive to hormonal therapy.
Human epidermal growth factor two (HER2)
The breast cancer is also usually tested for the presence of human epidermal growth factor receptor 2, a protein also known as HER2, neu or erbB2. HER2 is a cell-surface protein involved in cell development. In normal cells, HER2 controls aspects of cell growth and division. When activated in cancer cells, HER2 accelerates tumor formation. About 20-30% of breast cancers overexpress HER2. Those patients may be candidates for the drug trastuzumab, both in the postsurgical setting (so-called "adjuvant" therapy), and in the metastatic setting.[87]
Treatment
The mainstay of breast cancer treatment is surgery when the tumor is localized, with possible adjuvant hormonal therapy (with tamoxifen or an aromatase inhibitor), chemotherapy, and/or radiotherapy. At present, the treatment recommendations after surgery (adjuvant therapy) follow a pattern. This pattern is subject to change, as every two years, a worldwide conference takes place in St. Gallen, Switzerland, to discuss the actual results of worldwide multi-center studies. Depending on clinical criteria (age, type of cancer, size, metastasis) patients are roughly divided to high risk and low risk cases, with each risk category following different rules for therapy. Treatment possibilities include radiation therapy, chemotherapy, hormone therapy, and immune therapy.
In planning treatment, doctors can also use PCR tests like Oncotype DX or microarray tests like MammaPrint that predict breast cancer recurrence risk based on gene expression. In February 2007, the MammaPrint test became the first breast cancer predictor to win formal approval from the Food and Drug Administration. This is a new gene test to help predict whether women with early-stage breast cancer will relapse in 5 or 10 years, this could help influence how aggressively the initial tumor is treated.[88]
Interstitial laser thermotherapy (ILT) is an innovative method of treating breast cancer in a minimally invasive manner and without the need for surgical removal, and with the absence of any adverse effect on the health and survival of the patient during intermediate followup [89].
Radiation treatment is also used to help destroy cancer cells that may linger after surgery. Radiation can reduce the risk of recurrence by 50-66% (1/2 - 2/3rds reduction of risk) when delivered in the correct dose. [90]
Early-stage research
In mice, flaxseed oil reduced the growth and metastasis of breast cancer tumors that were cultured in the laboratory and implanted in mice. In humans, flaxseed oil reduced markers that are associated with cancer growth.[91][92][93][94]
Prognosis
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This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. (October 2007) |
A prognosis is the medical team's "best guess" in how cancer will affect a patient. There are many prognostic factors associated with breast cancer: staging, tumour size and location, grade, whether disease is systemic (has metastasized, or traveled to other parts of the body), recurrence of the disease, and age of patient.
Stage is the most important, as it takes into consideration size, local involvement, lymph node status and whether metastatic disease is present. The higher the stage at diagnosis, the worse the prognosis. Larger tumours, invasiveness of disease to lymph nodes, chest wall, skin or beyond, and aggressiveness of the cancer cells raise the stage, while smaller tumours, cancer-free zones, and close to normal cell behaviour (grading) lower it.
Grading is based on how cultured biopsied cells behave. The closer to normal cancer cells are, the slower their growth and a better prognosis. If cells are not well differentiated, they appear immature, divide more rapidly, and tend to spread. Well differentiated is given a grade of 1, moderate is grade 2, while poor or undifferentiated is given a higher grade of 3 or 4 (depending upon the scale used).
Younger women tend to have a poorer prognosis than post-menopausal women due to several factors. Their breasts are active with their cycles, they may be nursing infants, and may be unaware of changes in their breasts. Therefore, younger women are usually at a more advanced stage when diagnosed.
The presence of estrogen and progesterone receptors in the cancer cell, while not prognostic, is important in guiding treatment. Those who do not test positive for these specific receptors will not respond to hormone therapy.
Likewise, HER2/neu status directs the course of treatment. Patients whose cancer cells are positive for HER2/neu have more aggressive disease and may be treated with trastuzumab, a monoclonal antibody that targets this protein.
Psychological aspects of diagnosis and treatment
The emotional impact of cancer diagnosis, symptoms, treatment, and related issues can be severe. Most larger hospitals are associated with cancer support groups which can help patients cope with the many issues that come up in a supportive environment with other people with experience with similar issues. Online cancer support groups are also very beneficial to cancer patients, especially in dealing with uncertainty and body-image problems inherent in cancer treatment.
Not all breast cancer patients experience their illness in the same manner. Factors such as age can have a significant impact on the way a patient copes with a breast cancer diagnosis. For example, a recent study conducted by researchers at the College of Public Health of the University of Georgia showed that older women may face a more difficult recovery from breast cancer than their younger counterparts.[95] As the incidence of breast cancer in women over 50 rises and survival rates increase, breast cancer is increasingly becoming a geriatric issue that warrants both further research and the expansion of specialized cancer support services tailored for specific age groups.[95]
Racial disparities in diagnosis and treatment
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It has been suggested that this article or section be merged with Epidemiology and etiology of Breast cancer and Breast cancer treatment () |
Several studies have found that black women in the U.S. are more likely to die from breast cancer even though white women are more likely to be diagnosed with the disease. Even after diagnosis, black women are less likely to get treatment compared to white women.[96][97][98] Scholars have advanced several theories for the disparities, including inadequate access to screening, reduced availability of the most advanced surgical and medical techniques, or some biological characteristic of the disease in the African American population.[99] Some studies suggest that the racial disparity in breast cancer outcomes may reflect cultural biases more than biological disease differences.[100] Research is currently ongoing to define the contribution of both biological and cultural factors.[101][97]
Metastasis
Most people understand breast cancer as something that happens in the breast. However it can metastasize (spread) via lymphatics to nearby lymph nodes, usually those under the arm. That is why surgery for breast cancer always involves some type of surgery for the glands under the arm — either axillary clearance, sampling, or sentinel node biopsy.
Breast cancer can also spread to other parts of the body via blood vessels or the lymphatic system. So it can spread to the lungs, pleura (the lining of the lungs), liver, brain, and most commonly to the bones.[102] Seventy percent of the time that breast cancer spreads to other locations, it spreads to bone, especially the vertebrae and the long bones of the arms, legs, and ribs. Breast cancer cells "set up house" in the bones and form tumors. Usually when breast cancer spreads to bone, it eats away healthy bone, causing weak spots, where the bones can break easily. That is why breast cancer patients are often seen wearing braces or using a wheelchair, and have aching bones.
When breast cancer is found in bones, it has usually spread to more than one site. At this stage, it is treatable, often for many years, but it is not curable. Like normal breast cells, these tumors in the bone often thrive on female hormones, especially estrogen. Therefore treatment with medicines that lower estrogen levels may be prescribed.
History
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Breast cancer may be one of the oldest known forms of cancer tumors in humans. The oldest description of cancer was discovered in Egypt and dates back to approximately 1600 BC. The Edwin Smith Papyrus describes 8 cases of tumors or ulcers of the breast that were treated by cauterization.The writing says about the disease, "There is no treatment."[103] For centuries, physicians described similar cases in their practises, with the same sad conclusion. It wasn't until doctors achieved greater understanding of the circulatory system in the 17th century that they could establish a link between breast cancer and the lymph nodes in the armpit. The French surgeon Jean Louis Petit (1674-1750) and later the Scottish surgeon Benjamin Bell (1749-1806) were the first to remove the lymph nodes, breast tissue, and underlying chest muscle. Their successful work was carried on by William Stewart Halsted who started performing mastectomies in 1882. He became known for his Halsted radical mastectomy, a surgical procedure that remained popular up to the 1970s.
Cultural references
In the month of October, breast cancer is recognized by survivors, family and friends of survivors and/or victims of the disease.[104] A pink ribbon is worn to recognize the struggle that sufferers face when battling the cancer.[105]
Pink for October is an initiative started by Matthew Oliphant, which asks that any sites willing to help make people aware of breast cancer, change their template or layout to include the color pink, so that when visitors view the site, they see that the majority of the site is pink. Then after reading a short amount of information about breast cancer, or being redirected to another site, they are aware of the disease itself.[106]
The patron saint of breast cancer is Saint Agatha of Sicily.[107]
Gallery
 Breast self exam |
 Illustration of the early warning signs of breast cancer (click for larger image) |
 Woman undergoing mammogram |
Mammography pictures, normal (left) and cancerous (right) |
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Mammogram displaying breast cancer, indicated with an arrow (click for larger view) |
 Mastectomy patient |
 Breast prostheses used by some mastectomy patients |
 Drawing of inflammatory breast cancer |
 Patient with advanced local-regional recurrence of breast cancer with an ulcerating axillary mass |
 Mastectomy specimen containing a very large cancer of the breast (in this case, an invasive ductal carcinoma) |
 Typical macroscopic (gross) appearance of the cut surface of a mastectomy specimen containing a cancer, in this case, an invasive ductal carcinoma of the breast, pale area at the center |
 Excised human breast tissue, showing a stellate area of cancer 2cm in diameter. The lesion could be felt clinically as a hard mobile lump, not attached to skin or chest wall. |
 Benign granular cell tumor removed from a woman's breast. Granular cell tumors of the breast represent one of the few lesions that can impersonate an invasive breast cancer on gross examination. |
 Infiltrating ductal carcinoma of the breast |
 Infiltrating ductal carcinoma of the Breast assayed with anti Mucin 1 antibody |
.jpg) Breast cancer (Infiltrating ductal carcinoma of the breast) assayed with anti HER-2 (ErbB2) antibody |
.jpg) Invasive lobular carcinoma of the breast demonstrating a predominantly lobular growth pattern |
 Metaplastic (sarcomatoid) carcinoma of the breast. |
.jpg) Histopathologic image from ductal cell carcinoma in situ (DCIS) of breast. Hematoxylin-eosin stain. |
.jpg) Histopathology of invasive ductal carcinoma of the breast representing a scirrhous growth. Core needle biopsy. Hematoxylin and eosin stain. |
_HER2_expression.JPG) Histopathology of invasive ductal carcinoma of the breast representing a scirrhous growth. Core needle biopsy. HER-2/neu oncoprotein expression by Ventana immunostaining system. |
 Breast cancer (Infiltrating ductal carcinoma of the breast) dyed with H&E |
.jpg) Histopathology of intraductal papilloma of the breast by excisional biopsy. Hematoxylin and eosin stain. |
_smooth_muscle_actin.JPG) Histopathology of intraductal papilloma of the breast by excisional biopsy. Immunostaining for alpha-smooth muscle actin. |
_p63.JPG) Histopathology of intraductal papilloma of the breast by excisional biopsy. Immunostaining for p63 protein. |
_DG_stain.jpg) Breast fibroadenoma |
_PAP_stain.jpg) Breast fibroadenoma |
.jpg) Histopathologic image of breast fibroadenoma. Core needle biopsy. Hematoxylin & eosin stain. |
.jpg) Histopathologic image of breast fibroadenoma. Core needle biopsy. Hematoxylin & eosin stain. |
Histopathology of intraductal papilloma of the breast by excisional biopsy. Hematoxylin and eosin stain. |
Histopathology of intraductal papilloma of the breast by excisional biopsy. Immunostaining for alpha-smooth muscle actin. |
Histopathology of intraductal papilloma of the breast by excisional biopsy. Immunostaining for p63 protein. |
See also
- List of notable breast cancer patients according to occupation
- List of notable breast cancer patients according to survival status
- List of breast carcinogenic substances
- Mammary tumor for breast cancer in other animals
- Breast reconstruction
- Alcohol and cancer
- Mammography Quality Standards Act
- National Breast Cancer Coalition
- National Comprehensive Cancer Network
- Breast Cancer Action
- Breakthrough Breast Cancer
- Living Beyond Breast Cancer
- Barron Lerner (Physician)
- International Agency for Research on Cancer
- The Hormone Foundation
- Susan G. Komen for the Cure
References
- ^ American Cancer Society (September 26, 2007). "What Is Breast Cancer?". Retrieved on 2008-02-03.
- ^ a b World Health Organization International Agency for Research on Cancer (June 2003). "World Cancer Report". Retrieved on 2008-02-03.
- ^ a b World Health Organization (February 2006). "Fact sheet No. 297: Cancer". Retrieved on 2007-04-26.
- ^ Laurance, Jeremy (2006-