According to results of a large study published Wednesday in the Journal of the National Cancer Institute, overweight and obese women are at increased risk of breast cancer and of being diagnosed with advanced disease.

The study, that looked at more than 287,000 women past menopause and took into account their mammogram habits, found that the overall breast cancer rates rose in tandem with weight, as did rates of advanced tumors.

The findings revealed the more obese a woman was, the higher her risk for breast cancer. Women who were overweight but not obese had a 10 percent to 35 percent increased risk of breast cancer compared to normal-weight women. While other risk factors - such as increasing age, being female, or having genetic mutations that raise breast cancer risk - are not changeable, losing weight remains under a woman's control.

Dr. Karla Kerlikowske, director of the Women Veterans' Comprehensive Health Center at the San Francisco Veterans Affairs Medical Center, noted: "Women who are above their healthy weight have higher levels of circulating estrogens. The estrogen promotes tumor growth."

For the study, Kerlikowske's team used the standard definitions of healthy weight, overweight, and obesity. For instance, a 5-foot, four-inch woman who weighs from 107 to
145 was considered at a healthy weight. The same woman weighing 146 pounds or more was considered overweight, and a weight of 175 pounds or more was considered obese.

Kerlikoswke said that the study gives women the message that two factors decrease the chance of being diagnosed with advanced-stage breast cancer - getting routine mammography and maintaining ideal body weight.