Tamoxifen

Status

FDA-approved. FDA-approved labeling exists for treatment of breast cancer and for risk reduction in women at high risk. It carries a boxed warning covering uterine malignancies, stroke and pulmonary embolism in the risk-reduction setting. No approved indication in men other than treatment of male breast cancer.

What it is

A selective estrogen receptor modulator with long clinical history.

What published research measured

A selective oestrogen receptor modulator with one of the largest evidence bases in oncology — decades of randomized trials establishing reductions in recurrence and mortality in oestrogen receptor-positive breast cancer, and reductions in incidence in prevention trials. It antagonizes oestrogen receptors in breast tissue while acting as an agonist in bone and the endometrium, which explains both its bone-sparing profile and its principal risk. The documented serious adverse effects are endometrial carcinoma, venous thromboembolism and pulmonary embolism, all established in randomized data rather than inferred. In men it is used off-label for gynaecomastia, where small trials support benefit, and its effect on the gonadal axis is used off-label in fertility contexts.

Source

EBCTCG meta-analyses of adjuvant tamoxifen · NSABP P-1 prevention trial · FDA labeling including the boxed warning

Sources

• Half-life source for Tamoxifen