Endometrial Cancer in Woman on Tamoxifen Requires No Unusual Treatment

By Martha Kerr

New York AUG 24, 2007 (Reuters Health) - Aggressive endometrial cancers that develop in breast cancer patients using adjuvant tamoxifen can be managed successfully with surgery, Canadian investigators report. The treatment success rate is equal to that of endometrial cancers not associated with tamoxifen.

"It has been recognized for more than ten years that patients receiving tamoxifen have a risk of about 1-2 cases per 1000 women treated per year of developing endometrial cancer. However ... the benefits of tamoxifen outweigh the risks, and it continues to be commonly used," investigator Dr. Ivo A. Olivotto commented in an interview with Reuters Health.

Dr. Olivotto and colleagues at the University of British Columbia in Victoria identified 163 women in the British Columbia Cancer Agency registry who had been diagnosed with breast cancer between 1988 and 1999 and who developed a subsequent endometrial cancer. Of these, 90 women (55%) had a history of tamoxifen treatment. Median follow-up was 9.4 years.

Aggressive endometrial cancers occurred in 28% of the women with a history of tamoxifen treatment compared with 14% of those who did not receive tamoxifen, the investigators report in the July 1st issue of Cancer.

Endometrial cancers were treated by hysterectomy and oophorectomy in 99% of cases, regardless of the nature of the malignancy. Pelvic control was similar in both tamoxifen-treated women and those who had not received tamoxifen.

Endometrial cancer-specific survival rates at 10 years were the same at 82% in the two groups, and overall survival rates at 10 years were 69% and 66% for tamoxifen- and non-tamoxifen-treated women, respectively.

"The study found that the chance of cure of the endometrial cancer was equal, whether the patient had used tamoxifen or not and that, as expected, the chance of dying of breast cancer was lower among women who used tamoxifen," Dr. Olivotto said.

"Based on the current study, the endometrial cancer, should it develop in a woman on tamoxifen, should be treated the same as any other endometrial cancer... generally with a hysterectomy," Dr. Olivotto said. No special additional testing is recommended for women on tamoxifen, added.

"This study does not raise new concerns about the use of tamoxifen. If anything, it is reassuring that patients who do develop endometrial cancer have no greater risk of death than if the endometrial cancer had developed spontaneously," Dr. Olivotto"s group concluded.

SOURCE:

• Cancer 2007;110:31-37.