Best time to beat breast cancer?

Women who schedule breast cancer surgery to coincide with certain days of the menstrual cycle may improve their chance of long-term survival, according to a controversial new report.

Ian S. Fentiman and his colleagues at Guy's Hospital in London, England, based their hypothesis on the knowledge that some breast tumors need the hormone estrogen to grow, and that the hormone progesterone counteracts estrogen's growth message. They speculated that women with breast tumors who undergo surgery on days when the body produces lots of estrogen but little or no progesterone would run the greatest risk of a deadly cancer recurrence. Unopposed estrogen, the reasoned, could fuel the proliferation of any tiny "seeds" of cancer that eluded the surgical knife.

To test the hypothesis, they studied the medical charts of 249 women with breast cancer tumors removed between 1975 and 1985. The team identified 75 women in this group who had gone into surgery three to 12 days after their last menstrual period began -- a time when estrogen is plentiful and progesterone is scant. They then compared the long-term survival rates of these patients with those of the 174 women whose operations had been performed at all other times of the cycle. At the time of surgery, the latter group had either very low estrogen levels or high levels of both estrogen and progesterone.

On average, the women undergoing breast surgery on days 3 to 12 had a 54 percent chance of surviving for another 10 years, while the rest of the group had an 84 percent chance of 10-year survival, the team reports in the May 25 LANCET. The gap in death rates showed up even when the researchers statistically controlled for other factors, such as tumor size, that can affect longevity after breast cancer surgery, they say.

The team now advises physicians to schedule breast cancer surgery during the second half of a patient's cycle.

Others remain unconvinced. F. Andrew Dorr of the National Cancer Institute notes that previous findings do not support the new results, and questions the precision of menstrual data based on patients' recollections.