June 3, 2010 -- A six-month chemotherapy regimen improves overall and disease-free survival among women with early breast cancer and lymph node involvement, when compared with two shorter regimens, a study shows.
The study is published in the June 3 issue of the New England Journal of Medicine.
Sandra M. Swain, MD, at the Washington Cancer Institute at Washington Hospital Center, and colleagues compared three chemotherapy regimens among 5,351 women with lymph-node positive early-stage breast cancer.
A 12-week, four-cycle regimen of doxorubicin and docetaxel.
A 24-week, regimen in which four cycles of doxorubicin and cyclophosphamide were given over the first 12 weeks, followed by four cycles of docetaxel alone the second 12 weeks.
Women who received the 24-week sequential chemotherapy regimen were more likely to survive than women given the other two chemotherapy regimens, the study showed. The 24-week sequential therapy also resulted in gains in disease-free survival when compared to the other two chemotherapy regimens.
The study shows that women who developed chemotherapy-induced lack of menstruation for six months or more seemed to do better than women who did not, regardless of their treatment and whether the breast cancer was estrogen-receptor positive or negative. Some breast cancer cells have receptors for the hormone estrogen and others do not.
Exactly why lack of menstruation was protective is not fully understood, but it may be a marker of the effectiveness of the treatments. It's also possible that suppressing the ovaries can have an effect on breast cancer, the researchers suggest. The ovaries produce the female sex hormone estrogen.
"This is an intriguing study that shows that the longer chemotherapy regimen did better than the shorter regimens in women with lymph-node-positive early breast cancer," says Marisa Weiss, MD, the president and founder of the advocacy group Breastcancer.org and the author of several books, including Taking Care of Your Girls: A Breast Health Guide for Girls, Teens, and In-Betweens.
Important questions remain, she says. For example, "what is it that [24-week] sequential ... vs. the other shorter-course regimens that provided this survival benefit?" she asks.