Experts: One-third of breast cancer is avoidable

BARCELONA, Spain — Up to a third of breast cancer cases in Western countries could be avoided if women ate less and exercised more, researchers at a breast cancer conference said Thursday.

While better treatments, early diagnosis and mammogram screenings have dramatically slowed the disease, experts said the focus should now shift to changing behaviors like diet and physical activity.

"What can be achieved with screening has been achieved. We can't do much more," Carlo La Vecchia, head of epidemiology at the University of Milan, told The Associated Press. "It's time to move onto other things."

La Vecchia spoke Thursday on the influence of lifestyle factors at a European breast cancer conference in Barcelona.

Breast cancer is the most common cancer in women. In Europe, there were about 421,000 new cases and nearly 90,000 deaths in 2008, the latest available figures. The United States last year saw more than 190,000 new cases and 40,000 deaths.

A woman's lifetime chance of getting breast cancer is about one in eight. Obese women are up to 60 percent more likely to develop any cancer than normal-weight women, according to a 2006 study by British researchers.

Many breast cancers are fueled by estrogen, a hormone produced in fat tissue. So experts suspect that the fatter a woman is, the more estrogen she's likely to produce, which could in turn spark breast cancer. Even in slim women, exercise can help reduce the cancer risk by converting more of the body's fat into muscle.

Any discussion of weight and breast cancer is a politically sensitive topic, for some may misconstrue that as the medical establishment blaming victims for getting breast cancer. Victims themselves could also feel guilty, wondering just how much a factor weight played in their getting the disease.

Ian Manley, a spokesman for Breast Cancer Care, a British charity, said his agency has always been very careful about issuing similar lifestyle advice.

"We would never want women to feel responsible for their breast cancer," he said. "It's a complex disease and there are so many factors responsible that it's difficult to blame it on one specific issue."

The recommendation to stay slim applies only to breast cancer in post-menopausal women, as there isn't enough evidence to know whether this applies to younger women.