Ending Periods Helps Cancer Survival

Dec. 15, 2006 (San Antonio) -- Breast cancer chemotherapy can cause menstruation to cease, and now a study shows that's a good thing.

Austrian researchers found women live longer and have fewer relapses if their periods stop.

In fact, women who continue to have a period despite chemotherapy might benefit from additional treatment to lower their levels of cancer-fueling estrogen, says Michael Gnant, MD, a breast cancer specialist at the Medical University of Vienna.

Breast Cancer and Menstruation

The study, presented at the annual San Antonio Breast Cancer Symposium, included more than 500 premenopausal women taking chemotherapy drugs for breast cancer.

About half stopped having their periods because of the cancer-killing drugs.

All had hormone-receptor-positive tumors. The growth of such breast cancers is fueled by hormones; this is the most common type of the disease.

By 10 years after starting treatment, women whose periods had stopped were 40% less likely to suffer a recurrence than those whose didn't, the study showed.

They were also 10% less likely to die, Gnant says.

Further analysis showed that almost all the benefit was in women under 40 at the time they started therapy, he says.

Chemo May Exert One-Two Punch

The results suggest chemotherapy has a dual effect in some women: It not only directly kills cancer cells, but also works indirectly by suppressing the ovaries, Gnant says.

"When you suppress the ovaries and stop menstruation, there is less estrogen available. Since estrogen stimulates hormone-receptor-positive tumors to spread, taking it away helps," he tells WebMD.

Whether taking ovary-suppressing drugs can help women who continue to menstruate despite chemotherapy is a question being studied in large, ongoing trials.

Such drugs, which include Zoladex and Synarel, cut estrogen production to levels women have after menopause.

While awaiting those studies' results, women whose menstruation doesn't stop despite chemotherapy may want to talk to their doctor about taking an ovary-suppressing drug, says Kathy Albain, MD, a breast cancer specialist at Loyola University of Chicago Medical Center.

"I already tell my younger patients with hormone-receptor-positive breast cancer that there is probably a survival advantage to shutting down their period," she tells WebMD. "But not all want [the drugs]; some women may want to have a family."