I Had Heard That Women With Breast Cancer Can Get Uterine Cancer. Is That True?
Women who are taking a selective estrogen blocker like Tamoxifen can indeed get uterine cancer. This happens because Tamoxifen will specifically block estrogen from seeing breast tissue, but not anywhere else. That is, it acts selectively when blocking the estrogen receptor. This means that other tissue, like bones and the uterus, perceive Tamoxifen as an estrogen, and in the uterus, it can cause the lining to build up. Since there is no period of withdrawal from this estrogenic stimulation, the buildup can persist and can predispose to the development of uterine cancer.
Frequently, the primary sign of a problem when on Tamoxifen is abnormal uterine bleeding. If this hap-pens, you should see your doctor immediately. The work-up usually entails an ultrasound of the uterus to see if thickening is present (often referred to as the endometrial stripe). The work-up also calls for a tissue analysis, often obtained from an endometrial curettage or biopsy. Beyond this, women who have had breast cancer can develop uterine cancer as part of a genetic risk. These cancers are a part of the HNPCC syn-drome. It is important to note that most women who take Tamoxifen will not develop endometrial cancer.
In the early very large studies of Tamoxifen and women with breast cancer, the women who developed endometrial cancer developed it very early, in the first 12 months of taking Tamoxifen. This might suggest that these women had an underlying abnormality of their endometrium that was not diagnosed before they started Tamoxifen. If you are going to take Tamoxifen it is important to see your gynecologist regularly and report any abnormal vaginal bleeding you might be having before you start the Tamoxifen or while you are taking it.