Weight loss after menopause reduces the risk of breast cancer

A new study found that women who lost 5% or more of their body weight after menopause had 12% less risk of breast cancer compared to women with stable weight.

Analysis of more than 61,000 women in the Women's Health Initiative (WHI) observational study also revealed that, although not associated with overall risk, weight gain of 5% or more correlated with a 54% higher incidence of triple negative breast cancer, Rowan Chlebowski. , MD, PhD, of the National Medical Center City of Hope in Duarte, California, and his colleagues reported in Cancer.

"Few studies have shown that weight loss can reduce the risk of breast cancer," Chlebowski said. MedPage today. "This is one of the few studies to do it."

Although obesity has been strongly linked to breast cancer risk, previous studies to determine whether weight loss could reduce postmenopausal risk have yielded mixed results, according to the basic information provided in the report. # 39; study.

Chlebowski said the new findings are consistent with those of the WHI Dietary Modification trial, in which breast cancer patients randomized to a low-fat diet had statistically significant but modest weight loss ( 3%) associated with an improvement in overall survival compared with women in a usual diet control group.

"Referral to appropriate interventionists and dietitians for postmenopausal women with diagnosed breast cancer seems a reasonable choice to recommend," he said.

In the WHI observation study, participants were aged 50 to 79 years, had no history of breast cancer and their mammography results were normal. About 85% were Caucasian. Demographic characteristics were documented and weight, height and body mass index (BMI) were assessed at entry and again 3 years later.

Participants were divided into four categories of analysis: stable weight, weight gain, intentional weight loss, and unintended weight loss (an unintended loss that may indicate morbidity or a change in socio-economic status).

With an average follow-up of 11.4 years, there were 3,061 cases of invasive breast cancer. The mean time between the determination of the weight of year 3 and the diagnosis was 6.47 years (range 0.005-17.0 years). The earliest weight loss was maintained until the sixth year.

Of the 8,175 women in weight loss, the breast cancer risk HR was 0.88 (95% CI: 0.78-0.98). P= 0.02) compared to 41 139 stable weight homologs, with no observed interaction by BMI. The fit for mammography did not change these results. No significant difference emerged from intentional or unintentional weight loss.

As for the timing of weight loss, Chlebowski said that no information was available about the time required for weight loss after menopause, as no age-related interactions have been observed.

With regard to the type of weight loss, compared to the stable group, women who had intentional weight loss were more likely to have a higher BMI and less likely to be physically active or to have used a treatment. hormonal replacement of menopause (P<0.01).

For the 4,829 women who reported intentional weight loss, the average loss over the third year was 19.56 pounds (standard deviation 27,12); the average weight loss for the 3,346 individuals reporting unintended weight loss was 16.90 pounds (SD 18.69).

Compared to their weight in the third year, the intentional weight loss group gained a self-reported 2.55 pound (SD) of 6 years, and the unintentional weight loss group took 1.82 pounds ( standard deviation 12.03).

Compared to the stable group, women whose weight gain was at least 5% (n = 12,021) were more likely to be younger, black, smoker and younger at the birth of their first child. With regard to the interesting combination of weight gain with triple negative breast cancer (HR 1.54, 95% CI 1.16-2.05), the possible causal factors are unclear.

"While hormone-related changes may play a role, it is more likely that other factors associated with obesity, such as markers of inflammation and metabolic syndrome components, play a bigger role, "said Chlebowski. In the absence of a strong biological justification for this correlation, it should be interpreted with caution.

Current results are consistent with studies of bariatric surgery in which significant weight loss, typically greater than 20 kg, is associated with a lower risk of breast cancer.

"As the study shows, there was no weight interaction and the risk ratio was less than 1 in non-obese women, so I think losing a few pounds would probably be beneficial." even for women who have normal weight problems, "said Chlebowski. In her opinion, these data, combined with evidence from the randomized dietary trial, clearly indicate that weight loss may also benefit postmenopausal women with established breast cancer.

Among the limitations of the study, the authors noted the baseline weight measurement and the third year only, as well as the observation plan (which excluded causal inference).

2018-10-08T18: 00: 00-0400