For breast cancer patients who later developed endometrial cancer, prior treatment with tamoxifen does not reduce the chances of survival, researchers report.

Women with breast cancer also have an increased risk for cancer of the endometrium, the lining of the uterus, Dr. Karen H. Lu and colleagues note in the July issue of Obstetrics and Gynecology. While tamoxifen is effective in preventing breast cancer and its recurrence, the drug’s effect on prognosis when endometrial cancer occurs has been unclear.

To investigate, Lu’s team, from M. D. Anderson Cancer Center in Houston, analyzed data on 89 women who developed endometrial cancer after surviving breast cancer. Forty-six of the patients had taken tamoxifen.

Clinically, endometrial cancer was similar in tamoxifen users and non-users, the investigators found. Moreover, there was no significant difference between the groups in mortality overall or specifically due to endometrial cancer.

However, the interval from breast cancer to endometrial cancer diagnosis averaged 77.2 months in tamoxifen users, whereas the interval in nonusers was 121.3 months, Lu and colleagues report.

SOURCE: Obstetrics and Gynecology, July 2004.