Abstract B57: Breast cancer subtypes and survival in a hospital-based sample in Puerto Rico

Abstract

Abstract Introduction: Breast cancer is the most common female malignancy in Puerto Rico and the United States. Breast cancer is a multifaceted disease comprised of distinct biological subtypes with diverse etiology, therapeutic indications and clinical outcomes. Information on the impact of hormone receptor status sub-types in disease prognosis is still limited for Hispanics. To overcome this limitation, we aimed to evaluate the association of breast cancer subtypes and other clinical factors with breast cancer survival in a hospital-based female population of breast cancer cases. Methods: We analyzed data from female patients with invasive breast cancer diagnosed between 2000-2005, at the I. Gonzalez Martinez Hospital and the Auxilio Mutuo Hospital (n=974). Information on Her2/neu (Her2) overexpression, Estrogen receptor (ER) and Progesterone receptor (PR) status and other clinical characteristics was retrieved from the hospitals’ cancer registries, the Puerto Rico Central Cancer Registry and from medical and pathology record review. Survival by covariates of interest was estimated using the Kaplan-Meier method, and survival curves were compared using the Wilcoxon test. Multivariate Cox proportional hazards models were employed to assess factors associated to breast cancer survival. Results: Overall, 22.5% of breast cancer cases were Her2+, 16.6% were triple negative (ER-/PR-/Her2-) and 60.9% were Her2-/ER+ or PR+. Factors associated to breast cancer death in bivariate analyses included younger age at diagnosis (< 50 years) (HR=1.70, 95% CI: 1.17-2.49), ER- (HR=1.91, 95% CI: 1.38-2.64), PR- (HR=1.10, 95% CI: 1.51 −2.07) and triple negative status (HR=2.45, 95% CI: 1.72-3.48); no differences were observed by Her2 status (p>0.05). Meanwhile, women with regional (HR=1.83, 95% CI: 1.29-2.61) and distant (HR=9.21, 95% CI:4.94-17.17) disease at time of diagnosis had higher risk of death as compared to those with localized disease. In multivariate analysis, Her2 positivity was still not associated with breast cancer mortality after adjusting for age and stage at diagnosis (HR=1.22, 95% CI:0.83-1.78). Meanwhile, women with triple-negative breast cancer had higher risk of breast cancer death after adjusting for age and stage at diagnosis (HR=2.65, 95% CI:1.80-3.88). Conclusions: This is the most comprehensive epidemiological study to date on the impact of hormone receptor expression sub-types in breast cancer survival in Puerto Rico. The clinical correlates of breast cancer survival in this population follow the same trends described previously in US populations. Even though no significant differences in survival were observed by Her2 overexpression status, consistent to results in other populations, the triple negative subtype was associated with decreased survival. The results of this study are useful for the development of breast cancer control strategies in Puerto Rico. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):B57.