Abstract 30: The epidemiology of triple-negative breast cancer: A review.

Background: Molecular profiling of breast tumors has enhanced our knowledge of the heterogeneity of breast cancer, including the identification of subtypes associated with differences in prognosis. However, the etiology of these intrinsic subtypes remains unknown. The triple-negative subtype accounts for 10-25% of breast tumors and is most common among African-American and premenopausal women. The purpose of this review was to summarize the existing literature on the risk factors for triple-negative disease.

Methods: Epidemiologic studies published between January 2000 and December 2011 that reported subtype-specific effect measure estimates for hormonal and other breast cancer risk factors in case-only or case-control analyses were included. A total of 20 studies from 17 populations met our pre-specified inclusion criteria.

Results: Compared to luminal A, triple-negative cases were more likely to have younger age at menarche, higher parity, shorter duration of breastfeeding, and increased premenopausal body mass. Case-control data suggest that there may be positive associations between parity, premenopausal body mass and risk of triple-negative disease, while inverse associations were observed for age at first term full-term pregnancy.

Conclusions: Our review confirms that risk factor profiles may vary by subtype; although we were unable to draw definitive conclusions regarding all hormonal risk factors and risk of triple-negative disease.

Impact: Because this subtype represents a small proportion of tumors, collaborative efforts should be undertaken to precisely evaluate potential associations. In addition, future investigations should focus on enrolling a greater number of African-American participants, as this population is underrepresented in the majority of current studies.

Citation Format: Lauren E. McCullough, Leila Family, Katie M. O'Brien, Hilda Razzaghi, Danielle M. Backes, Irina Mordukhovich, Paul L. Reiter, Andrew F. Olshan. The epidemiology of triple-negative breast cancer: A review. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 30.