Is it possible that young women with breast cancer live longer if the operation to remove the cancer is performed during the middle of the menstrual cycle rather than at the beginning? The answer depends on how long ago the surgery was done. Prior to 1984, surgery done during the onset of menstruation almost doubled the risk of dying compared to surgery around the time of ovulation, according to the results of a new study led by a New York University School of Medicine researcher.
The study, led by Susan Harlap, M.D., Research Professor of Epidemiology in the Department of Obstetrics and Gynecology at NYU School of Medicine, examines the notion that timing breast cancer surgery to a particular phase of the menstrual cycle influences subsequent survival.
"This is an enormously controversial subject," says Dr. Harlap. "Our new data has shown that the timing of surgery influenced survival for women diagnosed with breast cancer in the late 1970s and early 1980s. But is it still important? We don't know, but the answer seems to be no. In the mid-1980s, something changed. From 1984 to 1988, the latest date covered by our study, the timing of surgery in the menstrual cycle has been unimportant.
"Right now we don't advocate scheduling breast cancer surgery on any particular day of the menstrual cycle," she says.
What might have changed in medical practice? Harlap points out that not only have surgical practice and chemotherapy changed, but so also have the drugs used for the anesthetic, as well as for post-operative pain control. "Patients are now kept warmer during the operation, fewer need blood transfusions and infection control has improved," she says. Harlap and her colleagues speculate that any one of these changes may have benefited breast cancer patients, as they are known to influence survival in other kinds of cancer.
Some previous studies have shown that surgery during the first half of the cycle compared to the second half lengthens survival, but other studies have failed to show an association. Some scientists have suggested that fluctuating hormone levels, especially high estrogen levels in the first half of the menstrual cycle, may alter populations of cancer and immune cells, making cancer cells more likely to spread if surgery occurs during this part of the cycle. "Our results dispute this notion," says Harlap.
The new study followed 614 premenopausal women who underwent breast cancer surgery between 1978 and 1988 at Memorial Sloan-Kettering Cancer Center in New York. These women had been interviewed shortly after their operations and asked about the length of their menstrual cycle, among other questions.
Prior to 1984, the patients who underwent surgery around the time they should have been ovulating were twice as likely to survive than those who had surgery at about the onset of menstruation, according to the study. After 1984, however, the association disappeared; women who had surgery at the onset of menstruation were just as likely to survive as those who had surgery at the time of ovulation.
The study is published in the July issue of Cancer, a journal published by the American Cancer Society.
"The change, whatever it was, was of great benefit. Women live longer now after breast cancer surgery" says Harlap. But she is mystified why the menstrual cycle should have any relationship to this benefit. "I am curious, and would like to understand this phenomenon a lot better."
Has the controversy over the timing of breast cancer surgery ended? Dr. Harlap says that the new study does not end the controversy because the results after 1984 may be due to chance. "This controversy isn't resolved. It may be that changes in medical care, whatever they were, resolved the problem, but we need more studies to say it is so."
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Cancer