Post-diagnosis weight change, body mass index, and breast cancer survival

Gaining weight following a diagnosis of invasive breast cancer could increase a woman's risk of death from the disease by more than half, according to researchers leading the Collaborative Women's Longevity Study. In fact, the researchers associated weight gain with a measurable increase in risk of death due to all causes, not just breast cancer.

"Our findings provide additional support for the benefits of maintaining a healthy weight and exercising," said Hazel B. Nichols, a doctoral student in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health. "According to our results, there is a 14 percent increase in risk for every five kilograms - about 11 pounds - of weight gained."

To analyze the effect of weight gain on breast cancer survival, Nichols and her colleagues contacted women who had taken part in one of three previous studies begun in 1988 at sites in Wisconsin, Massachusetts and New Hampshire.

Between 1998 and 2001, Nichols' team surveyed the women about post-diagnosis weight, weight gain, physical activity, diet and related items.

Of the original 4,021 breast cancer patients, the researchers identified 121 breast cancer-related deaths and 428 total deaths. For women classified as obese by body mass index - a measure of weight and height - the risk of dying from breast cancer was nearly 2.4 times that of women classified with a normal body weight. "Obesity was associated with risk of death even after accounting for age, menopausal status or smoking," Nichols said.

Nichols' study was funded by the Susan G. Komen for the Cure Breast Cancer Foundation.

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