INDICATIONS AND USAGE
Metastatic Breast Cancer
Tamoxifen citrate tablets are effective in the treatment of metastatic breast cancer in women and men. In premenopausal women with metastatic breast cancer, tamoxifen is an alternative to oophorectomy or ovarian irradiation. Available evidence indicates that patients whose tumors are estrogen receptor positive are more likely to benefit from tamoxifen therapy.
Adjuvant Treatment of Breast Cancer
Tamoxifen citrate tablets are indicated for the treatment of node-positive breast cancer in women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation. In some tamoxifen adjuvant studies, most of the benefit to date has been in the subgroup with four or more positive axillary nodes.
Tamoxifen citrate tablets are indicated for the treatment of axillary node-negative breast cancer in women following total mastectomy or segmental mastectomy, axillary dissection, and breast irradiation.
The estrogen and progesterone receptor values may help to predict whether adjuvant tamoxifen therapy is likely to be beneficial.
Tamoxifen reduces the occurrence of contralateral breast cancer in patients receiving adjuvant tamoxifen therapy for breast cancer.
Ductal Carcinoma in Situ (DCIS)
In women with DCIS, following breast surgery and radiation, tamoxifen citrate tablets are indicated to reduce the risk of invasive breast cancer (see
BOXED WARNING
at the beginning of the label). The decision regarding therapy with tamoxifen for the reduction in breast cancer incidence should be based upon an individual assessment of the benefits and risks of tamoxifen therapy.
Current data from clinical trials support 5 years of adjuvant tamoxifen therapy for patients with breast cancer.
Reduction in Breast Cancer Incidence in High Risk Women
Tamoxifen citrate tablets are indicated to reduce the incidence of breast cancer in women at high risk for breast cancer. This effect was shown in a study of 5 years planned duration with a median follow-up of 4.2 years. Twenty-five percent of the participants received drug for 5 years. The longer-term effects are not known. In this study, there was no impact of tamoxifen on overall or breast cancer-related mortality (see
BOXED WARNING
at the beginning of the label).
Tamoxifen citrate tablets are indicated only for high-risk women. "High risk" is defined as women at least 35 years of age with a 5 year predicted risk of breast cancer
1.67%, as calculated by the Gail Model.
Examples of combinations of factors predicting a 5 year risk
1.67% are:
Age 35 or older and any of the following combination of factors:
One first degree relative with a history of breast cancer, 2 or more benign biopsies, and a history of a breast biopsy showing atypical hyperplasia; or
At least 2 first degree relatives with a history of breast cancer, and a personal history of at least 1 breast biopsy; or
LCIS
Age 40 or older and any of the following combination of factors:
One first degree relative with a history of breast cancer, 2 or more benign biopsies, age at first live birth 25 or older, and age at menarche 11 or younger; or
At least 2 first degree relatives with a history of breast cancer, and age at first live birth 19 or younger; or
One first degree relative with a history of breast cancer, and a personal history of a breast biopsy showing atypical hyperplasia.
Age 45 or older and any of the following combination of factors:
At least 2 first degree relatives with a history of breast cancer and age at first live birth 24 or younger; or
One first degree relative with a history of breast cancer with a personal history of a benign breast biopsy, age at menarche 11 or less and age at first live birth 20 or more.
Age 50 or older and any of the following combination of factors:
At least 2 first degree relatives with a history of breast cancer; or
History of 1 breast biopsy showing atypical hyperplasia, and age at first live birth 30 or older and age at menarche 11 or less; or
History of at least 2 breast biopsies with a history of atypical hyperplasia, and age at first live birth 30 or more.
Age 55 or older and any of the following combination of factors:
One first degree relative with a history of breast cancer with a personal history of a benign breast biopsy, and age at menarche 11 or less; or
History of at least 2 breast biopsies with a history of atypical hyperplasia, and age at first live birth 20 or older.
Age 60 or older and:
Five-year predicted risk of breast cancer
1.67%, as calculated by the Gail Model.
For women whose risk factors are not described in the above examples, the Gail Model is necessary to estimate absolute breast cancer risk. Health Care Professionals can obtain a Gail Model Risk Assessment Tool by dialing 1-844-825-8500.
There are insufficient data available regarding the effect of tamoxifen on breast cancer incidence in women with inherited mutations (BRCA1, BRCA2) to be able to make specific recommendations on the effectiveness of tamoxifen in these patients.
After an assessment of the risk of developing breast cancer, the decision regarding therapy with tamoxifen for the reduction in breast cancer incidence should be based upon an individual assessment of the benefits and risks of tamoxifen therapy. In the NSABP P-1 trial, tamoxifen treatment lowered the risk of developing breast cancer during the follow-up period of the trial, but did not eliminate breast cancer risk (see
Table 3
in
CLINICAL PHARMACOLOGY).