Older weight loss women may have a lower risk of developing invasive breast cancer than those who maintain or gain weight, according to a large US study.
While obesity has long been associated with increased risk for breast cancer, previous studies offered a mixed picture of the potential for weight loss to reduce this risk. For the present study, researchers have estimated the weight and height for calculating the BMI for more than 61,000 women for two to three years.
Then, researchers have watched women average for 11.4 years. During this time 3,061 women developed invasive breast cancer.
Compared to women who had a stable weight during the first three years of research, women who lost at least 5 percent of their body weight during the first three years were 12 percent less likely to develop breast cancer over the next decade or so.
"Our findings are consistent with women who can reduce cancer risk, even if they remain overweight or obese after weight loss, since virtually no women in our current collective analysis have lost enough weight to achieve normal weight, said Dr. Rowan Chlebowsky of the Nada National Medical Center at Duarte, California.
"This should be a encouraging result for women because modestly viable weight loss can be achieved by many, while weight loss is enough to return to a category that is not overweight or overweight," Chlebowski said.
All women in the study have gone through menopause when menstruation stops and the production of estrogen hormone decreases. After menopause, the main source of estrogen is female fatty tissue; Excess body weight or obesity may increase the risk of cancer because estrogen can help tumor growth.
"Women who have excessive body weight or obesity are likely to have an increased risk of postmenopausal breast cancer due to increased levels of hormone-related fat cells," said Dr. Daniel Schauer of the University of Cincinnati School of Medicine, who was not included in the study.
"These hormones, especially estrogen, can promote the development of breast cancer in postmenopausal women," Schauer told Reuters Health e-mail. "Weight loss reduces the level of circulating hormones."
Of the approximately 41,000 women in the study who had a stable weight during the first three years, the participants had an average BMI of 26.7, which is considered to be overweight.
12,000 women who gained body weight during the study started with an average BMI of 26.7.
Women who lost weight began to be more difficult.
About 3300 women who unintentionally lost weight began with a BMI of 27.9, and half lost more than 17 pounds. Women who deliberately lost weight began with an average BMI of 29.9, just shy of the BMI limit of 30 to be considered obese, and half lost more than 20 pounds.
A gain of 5 percent or more was not associated with an increased risk of breast cancer as a whole, researchers reported in the Cancer magazine. However, this amount of weight gain was associated with 54 percent higher risk of developing "triple negative" breast cancer, aggressive and severe treatment of cancer types.
The study was not a controlled trial that proved whether or how it changes over time can directly affect the risk of developing or dying of breast cancer.
Researchers only measured the weight of women twice, at the beginning of the study and again three years later, and all changes in the weight of women reported afterwards were not verified by medical examinations.
For most people, with increasing weight, Dr. Graham Colditz from the Washington University Medical School at St. Louise, who was not involved in the studio.
"So the first realistic goals are to work to stop getting. There are health benefits to that, even if you're overweight," Colditz said via email.
"After that, meaningful and slow weight loss is a good goal," Colditz added. "Five to ten pounds is a great start that is easier to maintain over time."
SOURCE: bit.ly/2AreUsz Cancer, online October 8, 2018.