Research Article Lifestyle Factors and the Risk of a Second Breast Cancer after Ductal Carcinoma In Situ

Background: Little information exists on lifestyle factors that affect prognosis after treatment for ductal carcinoma in situ (DCIS) breast cancer. Improved understanding of the role of lifestyle factors is important to survivors wishing to reduce their risk of a second breast cancer diagnosis. Methods: We examined the association between body mass index (BMI), physical activity, and alcohol intake, and risk of a second breast cancer diagnosis among 1,925 DCIS survivors in the Wisconsin In Situ Cohort. Exposureswere self-reported during biennial patient interviews. Second breast cancer diagnoseswere validated via pathology report. Cox proportional hazards regression was used to estimate the association between prediagnosis, postdiagnosis, and change in exposure levels and the risk of a second diagnosis, with adjustment for patient, tumor, and treatment factors. Results:Over amean of 6.7 years of follow-up, 162 second breast cancer diagnoseswere reported, including 57 invasive events, 60 in situ events, and 45diagnoses of unknown stage.A significant trendof increasing risk of a seconddiagnosiswas found over increasing categories of postdiagnosis alcohol intake (Ptrend 0.02). Among premenopausal women, increased prediagnosis BMIwas associated with a reduced risk of a second diagnosis (HR 0.93; 95 % confidence interval, 0.88–0.99). Conclusion:DCIS survivors may reduce their risk of a second diagnosis by reducing postdiagnosis alcohol consumption. Impact: The population of DCIS survivors is projected to surpass one million by the year 2016. Our results suggest that thesewomenmay be able to reduce their risk of a second diagnosis throughmoderation of alcohol consumption. Cancer Epidemiol Biomarkers Prev; 23(3); 450–60. 2014 AACR