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 Researchers compared two groups of women with morbid obesity: nearly
18,000 who underwent various forms of so-called bariatric surgery
and nearly 54,000 who did not. The groups were similar in terms of
age, medical conditions and body mass index (BMI, a ratio of weight
to height).
Researchers tracked the surgery group for an average of about 48
months and the no-surgery group for an average of about 41 months.
During the study period, women who had the weight-loss operations
had a 37 percent lower risk of developing breast cancer compared to
women who didn't, the researchers reported in Annals of Surgery.
The risk was lowered by 45 percent in postmenopausal women and by 28
percent in premenopausal women.
Among postmenopausal women, the reduction in risk was more
pronounced for estrogen receptor (ER)-positive cancers. These tumors
depend on the hormone estrogen for growth; the estrogen attaches to
proteins called receptors on the cancer cells.
Among premenopausal women, by contrast, the risk reduction was more
pronounced for ER-negative cancers, which don't depend on estrogen
to grow and are more common in younger women.
"The main takeaway is that the benefits are not exclusive to
postmenopausal women or ER-positive women and this adds to the now
growing body of literature supporting cancer reduction as a
meaningful benefit of weight loss," Dr. Brian Smith of UC Irvine
Health in Orange, California, who was not involved in the study,
told Reuters Health by phone.
That body of literature includes a large 2017 study that found
morbidly obese women who had bariatric surgery were less likely to
develop any type of cancer, not just breast cancer. (https://reut.rs/2E3ru2z)
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The most common bariatric procedure in the current study was
Roux-en-Y gastric bypass, which reduces the stomach to about the
size of an egg and rearranges the intestine so that food bypasses
part of it. Next most common was sleeve gastrectomy, which reduces
the stomach to the size of a banana.
According to the U.S. National Institute of Diabetes and Digestive
and Kidney Diseases, the benefits of weight loss surgery can also
include improvements in many health problems related to obesity,
such as type 2 diabetes, high blood pressure, high cholesterol,
sleep apnea, urinary incontinence, and knee and hip pain.
The researchers on the current study found, however, that the
reduction in breast cancer risk began to evaporate beginning about
three years after the operations were performed, possibly as people
tend to regain their weight.
Further studies will need to observe the patients for longer periods
and consider the amount of weight lost and regained to see if the
benefit of cancer risk reduction can be maintained, study leader
Heather Spencer Feigelson of the Kaiser Permanente Institute for
Health Research in Aurora, Colorado, told Reuters Health by phone.
"It could just be that this effect we're seeing is only a short-term
effect," she said.
SOURCE: https://bit.ly/2UyiRTd Annals of Surgery, online April 13
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