“Growing research suggests that body weight is not only related to the risk of developing malignancy, but also prognosis after diagnosis, especially in breast cancer,” said Jennifer A. Ligibel, MD, of Dana-Farber Cancer Institute and Harvard Medical School, at the 19th Annual Lynn Sage Breast Cancer Symposium, sponsored by the Robert H. Lurie Comprehensive Cancer Center of Northwestern Medicine, Chicago.¹ Magnifying the impact of that research is the dramatic rise in obesity in the United States, exceeding 38% among women, according to Centers for Disease Control and Prevention data. 

“Unfortunately, there are fairly high rates of obesity and inactivity and poor dietary quality in cancer survivors,” reflecting general patterns in the United States, Dr. Ligibel noted. An American Cancer Society study found that just over one-third of breast cancer survivors reported meeting recommendations for physical activity (at least 150 minutes of moderate-intensity aerobic exercise per week), and not even one-fifth consumed the recommended servings of fruit and vegetables.² “There is definitely a lot of room for improvement in terms of these lifestyle factors,” Dr. Ligibel said. 

Changing Lifestyle Factors 

But can improving these lifestyle factors, specifically diet and nutrition, improve outcomes for patients with breast cancer? Only two reported trials looked at the effects of dietary intervention on cancer recurrence, both launched more than 15 years ago, and with conflicting results. The Women’s Intervention Nutrition Study (WINS) randomized 2,400 women with resected early-stage breast cancer receiving conventional management to a low-fat diet intervention or to continue their usual diets (control group).³ 

“It is a really hard thing to help people change their behavior for 5 years, but the investigators in this study were able to help the intervention group lower their dietary fat intake by a third, reducing the percentage they consumed as fat from 30% of their daily calories to 20%. These changes were maintained for 5 years,” Dr. Ligibel said. 

Unfortunately, [the WINS and WHEL studies] put together don’t really give us clear guidance about what we should be telling our patients in terms of diet.

— Jennifer A. Ligibel, MD

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“Women who were randomized to the low-fat dietary intervention had a 24% reduction in the risk of breast cancer recurrences. Subsequent analysis suggested that the group randomized to this intervention did have a modest reduction in the risk of breast cancer–related and overall mortality, especially those with hormone receptor–negative cancers,” Dr. Ligibel said. 

At the same time as the WINS study, a second large-scale dietary intervention trial, the Women’s Healthy Eating and Living (WHEL) study, was being conducted among 3,088 women with previously treated early-stage breast cancer randomized to a phone-based dietary intervention or a control group.⁴ “The dietary intervention aimed not only to lower the intake of fat, but also to increase fruits, vegetables, and fiber,” Dr. Ligibel reported.

There were no dietary eligibility criteria, and participants represented a “pretty select population,” consuming about seven servings of fruit and vegetables per day, “which makes some of the results a little hard to interpret,” Dr. Ligibel noted. “Investigators were successful with their intervention, and at the end of the 4-year period, women who were randomized to the dietary intervention group increased their fruit and vegetable intake from 7 servings to 10. There was also a reduction in fat intake of about 6%.” 

But, she added, there was “absolutely no difference in the rates of recurrence in the intervention vs control group, which has led to some confusion about whether diet is really important in women with early breast cancer.” 

Breast Cancer Weight Loss Trial

“Unfortunately, these two studies put together don’t really give us clear guidance about what we should be telling our patients in terms of diet,” Dr. Ligibel stated. “One of things that really stands out is that patients in the dietary intervention group in the WINS trial lost weight; patients in the WHEL trial didn’t. Differences between the two studies make it impossible to say whether it was really weight loss that drove better outcomes in the WINS trials, but it does lay the groundwork for additional research. This is what has led to a trial that we are running now called the Breast Cancer Weight Loss (BWEL) study.”

BWEL is a phase III randomized trial to test the impact of a weight loss intervention on disease recurrence in women with stage II to III HER2-negative breast cancer. The study is powered to detect a 4% absolute decrease in recurrence in the weight loss group. 

The recruitment goal is 3,136 participants with a body mass index of 27 kg/m², which Dr. Ligibel described as “right in the middle of the overweight range,” or higher. “Patients will be randomized to the 2-year telephone-based weight loss intervention plus health education materials or to health education materials alone.” Those in the telephone-based intervention group will receive individual weight loss, caloric restriction, and physical activity goals from trained coaches. 

Connecting Biomarkers to Outcomes

The investigators will be collecting fasting blood at baseline, 6 months, and 24 months to be able to look at some of the metabolic and inflammatory biomarkers and “try to connect some of these biomarkers to actual outcomes in breast cancer,” Dr. Ligibel noted. 

“We are also collecting specimens of tumor and benign breast tissue from the time of initial breast surgery with the goal of really being able to tell who derives benefit from this type of intervention.… We currently have more than 1,000 sites throughout the United States that are actively recruiting participants, and in the first year after the study opened, we have enrolled 700 women,” demonstrating patients’ interest in this area, Dr. Ligibel stated. “We anticipate we will be enrolling patients over the next 3 years.” ■

DISCLOSURE: Dr. Ligibel reported no conflicts of interest.

REFERENCES

1. Ligibel J: Can weight loss and increased physical activity reduce the risk of breast cancer recurrence? 2017 Lynn Sage Breast Cancer Symposium. Presented September 14, 2017.

2. Blanchard CM, Courneya KS, Stein K: Cancer survivors’ adherence to lifestyle behavior recommendations and associations with health-related quality of life: Results from the American Cancer Society’s SCS-II. J Clin Oncol 26:2198-2204, 2008.

3. Chlebowski RT, Blackburn GL, Thomson CA, et al: Dietary fat reduction and breast cancer outcome. J Natl Cancer Inst 98:1767-1776, 2006.

4. Pierce JP, Natarajan L, Cain BJ, et al: Influence of a diet very high in vegetables, fruit, and fiber and low in fat on prognosis following treatment for breast cancer. JAMA 298:289-298, 2007.