Cancer risk lower for older mothers

WASHINGTON - At last, a health benefit to having children late in life - it seems to reduce the risk of ovarian cancer.

US researchers reported they found that women who had their last children after the age of 35 had a 58 per cent lower risk of ovarian cancer compared with women who had never had children.

Women who had children earlier in life also had a lower risk, but it was less dramatic - 16 per cent for women whose children were born before age 25, and 45 per cent for those whose children were born before age 30.

Women who had four or more children had a 64 per cent lower risk than women who had never given birth, Malcolm Pike of the University of Southern California and colleagues reported in the journal Fertility & Sterility.

Dr Pike's team interviewed 477 ovarian-cancer patients and 660 healthy women of similar race, ethnicity, age, and neighbourhood.

Women who had babies later in life were much less likely to have had ovarian cancer. The number of children did not matter.

"We found it was pretty consistent," said Dr Pike.

Earlier studies had shown that having children late in life also protected against cancer of the endometrium - the lining of the uterus.

He believed that the surge in the hormone progesterone that is seen in pregnancy could be a factor in both cancers.

"This level of progestins might very well be fatal to early disease," Dr Pike said.

As well, the uterus was "cleaned out" during birth and the delivery of the placenta, perhaps taking away ageing cells that were more likely to become cancerous.

Dr Pike believed the findings could have implications for preventing ovarian cancer, which, while rare, was deadly. "If you could work this out you could possibly do some prevention."

Dr Robert Schenken, president-elect of the American Society for Reproductive Medicine, which publishes the journal, agreed.

"The next challenge is to map out the mechanism of the last birth's effect on the ovaries. It would be a major advance in cancer prevention if, as the authors suggest, these findings lead to the development of a chemoprevention approach for women at high risk for ovarian cancer."

- REUTERS