TUESDAY, July 19 (HealthDay News) -- Giving the ovaries a rest when young women with breast cancer are undergoing chemotherapy may help prevent early menopause and preserve fertility.

According to new research in the July 20 issue of the Journal of the American Medical Association, shutting down the ovaries by giving the hormone triptorelin when a patient is undergoing chemotherapy helped prevent early menopause.

Triptorelin appears to protect the ovaries by halting ovarian function temporarily, although it's not entirely clear why. The authors found that among women who took triptorelin in addition to chemotherapy, more than 63 percent regained the ability to menstruate, compared to about 50 percent of the women who had chemotherapy alone.

The study authors suggest that this option could help women with breast cancer who want to prevent early menopause. About 6 percent of women with breast cancer are diagnosed before age 40, and chemotherapy is often associated with premature menopause.

But, experts not involved with the study had reservations about the use of triptorelin.

The treatment could have drawbacks, said Dr. Lauren Cassell, chief of breast surgery at Lenox Hill Hospital in New York City.

"Just because you resume menses [menstruation] doesn't mean that you're going to have fertilization. You don't really know how this is going to affect long-term outcomes," she said.

Dr. Paula Ryan, a medical oncologist with Fox Chase Cancer Center in Philadelphia had the same two concerns: that adding triptorelin might affect long-term breast cancer outcomes and may not even preserve fertility.

"I wouldn't take this study and ultimately suggest that it be the standard of care," she said.

The study looked only at younger, premenopausal women with breast cancer -- aged 18 to 45 -- and only those who had earlier-stage breast cancer.

Some 40 percent of women undergoing chemotherapy experience early menopause, although the incidence is more likely with certain types of chemo.

Right now, the best option for women with breast cancer wanting to have children or at least the option of having children is to go through in vitro fertilization before treatment, then have the embryo preserved, said Ryan.

The study authors acknowledged that their study did not prove that their treatment would preserve fertility. They also agreed that egg harvesting and preserving frozen embryos prior to breast cancer treatment is a relatively effective way for breast cancer patients to achieve pregnancy.

However, they noted that data from other trials had shown no difference in outcomes among women who suppressed ovarian function during chemotherapy and those who did not.

For this Phase 3 trial, 281 patients with Stage 1 to 3 breast cancer were randomized to receive either chemotherapy alone or chemotherapy with triptorelin.

One year after chemotherapy was completed, 26 percent of women in the chemotherapy-alone group experienced early menopause, vs. only 9 percent in the combined group, a reduction of 17 percent.

Meanwhile, 49.6 percent of women receiving chemotherapy alone resumed regular periods, vs. around 63.3 percent in the triptorelin group.

Women with hormone-receptor-negative tumors who did not receive tamoxifen (tamoxifen is not generally used for these types of malignancies) were more likely to start menstruating again.

But on the positive side, said Ryan, "this study, along with a few other small, randomized studies, that have pointed to a benefit [that] at least could potentially be encouraging for young women. One of the burdens of getting breast cancer, on top of everything else, in young women is this huge issue [of preserving fertility]. Any study looking at this is giving us new and important information for this particular group of women."

More information

Visit the U.S. National Cancer Institute for more on treatments for breast cancer.