Women who gain weight in adulthood -- particularly when they LTC are in their 30s -- face an increased risk of breast cancer, Florida researchers have found.
Their study of 218 newly diagnosed breast-cancer patients found that more than 63 percent of the women had gained at least 15 pounds since they turned 30, compared to 50 percent of those in a control group of healthy women.
More than 48 percent of the breast-cancer patients had gained 15 pounds or more since age 16, compared to 37 percent of the control group, according to the study, published in the current issue of the journal Cancer.
Previous studies showed a concentration of fat in the upper body raises a woman's risk of developing breast and endometrial cancers.
While during puberty fat is mainly distributed in the thighs, hips and buttocks, in adulthood -- including during pregnancy -- weight tends to collect more in the upper body, said Nagi Kumar, the study's lead author and director of the department of nutrition at the H. Lee Moffit Cancer Center in Tampa.
"Even if you don't believe you'll get breast cancer, it's really wise to watch your weight," Ms. Kumar said. "Even if you gained the weight during your 30s, it's always good to get back to your weight at age 19 or 20."
An extra 10 pounds on a 30-year-old woman raises her risk of developing breast cancer by 23 percent, and 20 extra pounds raises the risk 52 percent, according to the study.
But Virginia breast-cancer expert Dr. Nicholas Robert noted that even in light of the study's findings, a woman's lifetime risk of breast cancer is less than 16 percent.
Weight gain "would be considered to have a small impact," said Dr. Robert, of the Fairfax Hospital in Falls Church, Va. "But if someone really wants to try to reduce her chance of breast cancer, trying to be closer to her ideal body weight would make some sense."
Weight might be the only modifiable risk factor involved in the development of breast cancer, according to Ms. Kumar.
The best way to lose weight, the Florida researcher said, is to combine a sensible diet with exercise lasting a half-hour each day, four to five times a week.