Background: Obesity has been associated with decreased disease free survival and overall survival in postmenopausal breast cancer survivors. Proposed mechanisms for this finding include elevated estradiol levels, hyperinsulinemia, and increased inflammatory mediators. This feasibility study evaluated whether a low carbohydrate, calorie restricted dietary intervention could achieve weight loss and measurable metabolic changes in a group of obese postmenopausal breast cancer survivors.

Methods: Twenty-three early stage estrogen receptor positive breast cancer survivors were enrolled on a low carbohydrate, calorie-restricted dietary intervention. At time of enrollment the patient had to be deemed postmenopausal and have a BMI >28. Patients were not allowed to have an underlying inflammatory condition or be receiving treatment for diabetes. The mean age was 57 years old (42-68) with a mean weight of 220 lbs (171-300) and mean BMI of 37 (28-48.5). All subjects had completed surgery and adjuvant chemotherapy. The majority of patients were on endocrine therapy with 61% on an AI and 35% on tamoxifen. The dietary intervention utilized 0.5g protein/pound (actual body weight), less than 40 grams of carbohydrates and 800-1200 calories per day. The program provided weekly coaching, meal replacement protein products and nutritional supplements. Subjects were medically monitored with brief physical exams and labs done every 2 weeks for the first 12 weeks, then monthly thereafter. Subjects were seen by a health coach every week. The average weight loss period spanned 23 weeks (7-59 weeks) due to the variance in weight loss goals aimed at a BMI ≤28.

Results: The mean weight loss was 19.9% of total body weight, the equivalent of 43.7 pounds. Total body fat lost was 6.86%. Weight loss averaged 5.4 pounds in week one and 2.14 pounds per week in weeks 2-19.

Statistically significant declines in the total estrogen level (p = 0.0345), estrone (p = 0.0296), and estradiol serum levels (p = 0.0296) were demonstrated. A rapid decline in fasting insulin level was seen with a 23% decline by Week 3 (p = 0.0959), 26% by Week 7 (p = 0.0139), and 42% by Week 19 (p = 0.0071). A statistically significant improvement in the CRP level compared to baseline was also demonstrated with a 40% decrease at Week 19 (p = 0.0272).

Conclusions: Our results support that a low carbohydrate dietary intervention can be used to successfully achieve weight loss and improve metabolic parameters. This feasibility study provides additional support for larger trials evaluating the role of carbohydrate restriction in breast cancer survivors.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD2-5.