For decades, the drug tamoxifen -- a type of hormonal therapy given to breast cancer patients and women at increased risk of getting breast cancer -- has scared women because of the low but real risk that it may cause uterine cancer. Recent studies have given a new twist to this old problem.

Previous studies had shown an increased risk of endometrial cancer with the use of tamoxifen. More recent research suggests that this may not be entirely due to the drug. That’s because this increased risk also has been identified within one year of breast cancer diagnosis, before 1975 when tamoxifen was rarely used. An increased risk of breast cancer was also seen after endometrial cancer.

Women who are diagnosed with breast cancer have a 25 percent increased risk of developing another kind of cancer elsewhere in their body. So, although tamoxifen has been accused as a culprit, the fact may be that the patient was predisposed to getting uterine cancer (as well as other cancers) at some point in her life anyway.

Tamoxifen is highly effective in reducing a woman’s risk of breast cancer recurrence and reduces a woman’s risk of developing the disease by 47 percent. The risk of developing uterine cancer after taking tamoxifen is in the single digits. With close monitoring (pelvic exams and transvaginal ultrasound to measure the endometrial lining), early signs can be caught before uterine cancer even develops.