Benefits of Weight Loss in Breast Cancer

TON - September/October 2014 Vol 7 No 5

Two studies explored the beneficial effects of exercise and weight loss, one study in healthy women and another in breast cancer survivors.

The first study, SHAPE-2,1 found that active postmenopausal women (those who exercised and restricted their calories) had up to a 25% risk reduction in breast cancer compared with inactive women.

Both exercise plus diet and diet alone achieved the same magnitude of weight loss, but the exercise group had more robust effects on body composition and physical fitness.

Lead investigator was Anne Maria May, PhD, of the Julius Center for Health Sciences and Primary Care at the University Medical Center Utrecht in the Netherlands.

SHAPE-2 enrolled 243 inactive, overweight, nonsmoking women from the Netherlands. After a 4- to 6-week run-in period during which participants followed a standardized diet, participants were randomly assigned to a diet group (n=97), an exercise plus some caloric restriction group (n=98), or a stable-weight control group (n=48). The study period was 16 weeks.

The diet intervention entailed caloric reduction of 500 kcal per day. The exercise intervention consisted of 4 hours of moderate to vigorous resistance and endurance exercise per week plus reduced caloric intake by 250 kcal per day. The goal of both interventions was a weight loss of 5 kg to 6 kg; control participants were instructed to maintain their body weight.

The primary outcome measure of this study was change in serum levels of sex hormones at 16 weeks. Both intervention groups had similar demographic characteristics, with a mean age of 60 years and mean body mass index of 29 kg/m2. Both interventions met the primary end point for weight loss compared to controls (P < .001), while the weight remained stable in the control arm.

The exercise intervention group also achieved significant reductions in serum estradiol, free estradiol, and serum testosterone compared with controls (only free estradiol was lower in the diet group), and both intervention groups showed an increase in sex hormone–binding globulin compared with controls (P < .025). When findings were adjusted for the percentage change in body fat, however, the effects were attenuated or eliminated.

Patients who exercised showed significantly greater changes compared with the diet group for body weight, body fat, lean mass preservation, and physical fitness as measured by peak VO2 levels (all, P < .001).

The Lifestyle, Exercise, and Nutrition (LEAN) study,2 presented by Melinda Irwin, PhD, MPH, of Yale University in New Haven, Connecticut, explored the effects of weight loss on inflammatory and metabolic biomarkers in breast cancer survivors.

The LEAN study enrolled 100 overweight or obese breast cancer patients: 33 were assigned to usual care and were given American Institute for Cancer Research (AICR) nutrition and activity brochures as well as a 30-minute weight-loss counseling session at 6 months; 67 women were assigned to receive eleven 30-minute weight-loss counseling sessions (either in person or by telephone) over 6 months. The goal of the intervention was 10% weight loss, 150 minutes of physical activity per week, and 10,000 steps per day.

Fifty-two women (78%) completed the weight-loss counseling intervention compared with 29 women (88%) in the usual-care group. Participants were a mean age of 59 years and were overweight, physically inactive, highly educated, and postmenopausal, with a mean time since diagnosis of 2.8 years. Most women were non-Hispanic white, had stage I-II breast cancer, and were taking hormone
therapy.

Women in the intervention group (whether counseled by phone or in person) lost significantly more weight than those in the usual-care group (6% weight loss vs 2% weight loss, respectively).

Irwin said the women were motivated to lose weight and that is why they entered the study. It seems that motivation helped prevent weight gain, even in the usual-care group, she noted.

The telephone and in-person counseling groups were combined for analysis of effects on biomarkers. The diet groups achieved a 30% decrease in C-reactive protein, a marker of inflammation, versus 1% in the usual-care group; they also had greater decreases in insulin, glucose, leptin, and TNF-alpha and increases in adiponectin, IL-6, and IGF-1 compared to those receiving usual care.

The more weight loss the better, in this study. Women who lost more than 5% of body weight had more beneficial changes in these factors than women who lost less than 5% of body weight.

References

  1. May AM, van Gemert W, Peeters P, et al. Effects of equivalent weight loss, with or without exercise, on sex hormones related to breast cancer risk in postmenopausal women: the SHAPE-2 trial. Presented at: 50th Annual Meeting of the American Society of Clinical Oncology; May 30-June 3, 2014; Chicago, IL. Abstract 1504.
  2. Loftfield E, Harrigan M, Li F, et al. Effect of weight loss intervention on inflammatory and metabolic markers in breast cancer survivors: the lifestyle, exercise, and nutrition (LEAN) study. Presented at: 50th Annual Meeting of the American Society of Clinical Oncology; May 30-June 3, 2014; Chicago, IL. Abstract 1505.

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