Abstract P4-09-01: Impact of adherence to guidelines on nutrition and physical activity for breast cancer prevention in high-risk women

Abstract

Abstract Background: Women who are at high-risk for breast cancer based upon their family history or benign breast disease are candidates for chemoprevention and other risk reduction strategies. Breast cancer risk factors such as obesity, lack of physical activity and alcohol consumption represent important modifiable behaviors to target for prevention due to their high prevalence and negative impact on multiple chronic diseases. We evaluated the effect of adherence to cancer prevention guidelines for body mass index (BMI), alcohol consumption, physical activity and diet on breast cancer development and predictors of adherence to these guidelines among high-risk women. Methods: From 1991-2011, 2674 participants were enrolled to a prospective cohort study called the Women at Risk registry at the Columbia University Medical Center (CUMC) breast clinic and 1600 evaluable patients had complete data and at least one follow-up visit. The study population included women who met one or more of the following criteria: 1) one or more first-degree relatives with premenopausal breast cancer; 2) two or more first-degree relatives with postmenopausal breast cancer; 3) known BRCA1 or BRCA2 deleterious mutation carrier; 4) a biopsy-proven history of atypical hyperplasia or lobular carcinoma in situ. Women completed a baseline epidemiologic questionnaire and were followed for an average of 4.5 years during routine clinic visits with breast surgery. Using unconditional logistic regression, we examined the association between adherence to the following lifestyle factors and breast cancer risk among 90 prospectively-ascertained breast cancer cases and 1510 unaffected controls: 1) BMI of 18.5-25 kg/m2, 2) alcohol consumption of <1 serving per week, 3) eating a strict low-fat or vegetarian diet, 4) engaging in moderate physical activity daily. A total adherence score (range, 0-8) for the 4 health behaviors was calculated, where 0 = non-adherent, 1 = partially adherent, 2 = fully adherent. Linear logistic regression was conducted to assess the association between sociodemographics and known breast cancer risk factors with adherence score. Results: Median age: 47 years; race/ethnicity, White/Hispanic/Black/Asian/other/unknown (%): 76/7/4/2/5/6; first-degree family history of breast cancer: 57%; benign breast disease: 60%; BMI of 18.5-25 kg/m2: 66%; consumption of <1 serving of alcohol/week: 59%; strict low-fat/vegetarian diet: 20%; daily exercise: 20%. BMI greater than 25 kg/m2 was associated with a higher risk of developing breast cancer compared to those with a BMI less than or equal to 25 kg/m2 (RR = 2.69, 95% CI = 1.21-5.94), even after adjustment for diet and exercise. In multivariate analysis, older age (b = -0.013, 95% CI = -0.0257, -0.0003) and non-white race (β = -0.378, 95% CI = -0.761, 0.004) were associated with a lower adherence score for health behaviors. Conclusion: Among high-risk women, being overweight or obese was associated with a 2.7-fold increased breast cancer risk compared to those with a lean body weight. Older women and non-white women were less likely to adhere to cancer prevention guidelines. We have identified a potentially modifiable breast cancer risk factor and vulnerable populations to target for breast cancer prevention. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-09-01.