For women with ductal carcinoma in situ (DCIS) and women at high risk for breast cancer: serious and life-threatening events associated with tamoxifen in the risk reduction setting include uterine malignancies, stroke, and pulmonary embolism. Incidence rates for these events have been estimated from the NSABP P-1 trial (median length of follow-up 6.9 years).

Uterine malignancies consist of both endometrial adenocarcinoma (incidence rate per 1000 women-years of 2.2 for tamoxifen versus 0.71 for placebo) and uterine sarcoma (incidence rate per 1000 women-years of 0.17 for tamoxifen versus 0 for placebo).

For stroke, the incidence rate per 1000 women-years was 1.43 for tamoxifen versus 1 for placebo.

For pulmonary embolism, the incidence rate per 1000 women-years was 0.75 for tamoxifen versus 0.25 for placebo.