Tobacco use and race as copredictors of overall survival in patients with breast cancer.
20 Background: Tobacco use (TOB) has been linked to the development of breast cancer (BCa), but limited data exists linking TOB with overall survival (OS) and the influence of race on this relationship. Our previous research has shown that African-American (AA) patients with BCa have worse OS compared with Caucasian (C) patients. This retrospective study examines the effect of TOB on OS in BCa patients at Georgia Regents University (GRU) and the effect of race in conjunction with TOB on OS. Methods: Data were obtained from the GRU Tumor Registry. Inclusion criteria were all female patients diagnosed with BC between 2002 and 2010. The estimated hazard ratio (HR) from Cox regression was used to measure the association between TOB and OS. Race, age at diagnosis, and stage at diagnosis were considered for inclusion as covariates. A stratified OS analysis was also performed dividing patients by race (C vs. AA). Results: Data were collected on 836 females who met inclusion criteria. TOB was categorized as "none" vs. "any" at time of BCa diagnosis The Cox regression analysis indicated a decreased OS for women with any tobacco use (unadjusted HR, 1.45; p = 0.024). Statistical significance was retained when this HR was adjusted for race (HR, 1.47; p = 0.021) and age at diagnosis (HR, 1.45; p = 0.024), but not for stage at diagnosis (HR, 1.21; p = 0.266). In the stratified analysis, the results for C patients were similar to those obtained in the complete sample (HR, 1.62; p = 0.044). Statistical significance was not retained for AA patients (HR 1.31; p = 0.244). We compared C tobacco users (n = 157) vs. AA tobacco users (n = 127) (HR, 1.10; p = 0.716) and C tobacco non-users (n = 291) vs. AA tobacco non-users (n = 261) (HR, 1.36; p= 0.156) and found no statistical significance. Conclusions: Our analysis shows that patients with history of TOB at BCa diagnosis have a 45% chance of decreased OS compared to non-TOB users. The negative impact of TOB is still noted when adjusted for race and age at diagnosis but not for stage at diagnosis. When stratifying by race, we found that any TOB is a significant risk factor among C patients but not among AA patients. We conclude that any history of TOB at BCa diagnosis is an important negative prognostic factor for OS, and this is particularly true in C patients.