Letrozole (Page 5 of 12)

6.5 Second-Line Treatment of Advanced Breast Cancer

Study discontinuations in the megestrol acetate comparison study for adverse reactions other than progression of tumor were 5/188 (2.7%) on letrozole 0.5 mg, in 4/174 (2.3%) on letrozole 2.5 mg, and in 15/190 (7.9%) on megestrol acetate. There were fewer thromboembolic events at both letrozole doses than on the megestrol acetate arm (0.6% vs. 4.7%). There was also less vaginal bleeding (0.3% vs. 3.2%) on letrozole than on megestrol acetate. In the aminoglutethimide comparison study, discontinuations for reasons other than progression occurred in 6/193 (3.1%) on 0.5 mg letrozole, 7/185 (3.8%) on 2.5 mg letrozole, and 7/178 (3.9%) of patients on aminoglutethimide.

Comparisons of the incidence of adverse reactions revealed no significant differences between the high and low dose letrozole groups in either study. Most of the adverse reactions observed in all treatment groups were mild to moderate in severity and it was generally not possible to distinguish adverse reactions due to treatment from the consequences of the patient’s metastatic breast cancer, the effects of estrogen deprivation, or intercurrent illness.

Adverse reactions, regardless of relationship to study drug, that were reported in at least 5% of the patients treated with letrozole 0.5 mg, letrozole 2.5 mg, megestrol acetate, or aminoglutethimide in the two controlled trials are shown in Table 4.

Table 4: Percentage (%) of Patients with Adverse Reactions
*
Includes peripheral edema, leg edema, dependent edema, edema.
Includes musculoskeletal pain, skeletal pain, back pain, arm pain, leg pain.
Includes rash, erythematous rash, maculopapular rash, psoriasiform rash, vesicular rash.

Adverse

Reaction

Pooled

Letrozole

2.5 mg

(N = 359)

%

Pooled

Letrozole

0.5 mg

(N = 380)

%

Megestrol

Acetate

160 mg

(N = 189)

%

Aminoglutethimide

500 mg

(N = 178)

%

Body as a Whole

Fatigue

8

6

11

3

Chest Pain

6

3

7

3

Peripheral Edema *

5

5

8

3

Asthenia

4

5

4

5

Weight Increase

2

2

9

3

Cardiovascular

Hypertension

5

7

5

6

Digestive System

Nausea

13

15

9

14

Vomiting

7

7

5

9

Constipation

6

7

9

7

Diarrhea

6

5

3

4

Pain-Abdominal

6

5

9

8

Anorexia

5

3

5

5

Dyspepsia

3

4

6

5

Infections/Infestations

Viral Infection

6

5

6

3

Lab Abnormality

Hypercholesterolemia

3

3

0

6

Musculoskeletal System

Musculoskeletal

21

22

30

14

Arthralgia

8

8

8

3

Nervous System

Headache

9

12

9

7

Somnolence

3

2

2

9

Dizziness

3

5

7

3

Respiratory System

Dyspnea

7

9

16

5

Coughing

6

5

7

5

Skin and Appendages

Hot Flushes

6

5

4

3

Rash

5

4

3

12

Pruritus

1

2

5

3

Other less frequent (< 5%) adverse reactions considered consequential and reported in at least three patients treated with letrozole, included hypercalcemia, fracture, depression, anxiety, pleural effusion, alopecia, increased sweating and vertigo.

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