p53 status is more likely than basal subtype to predict survival in African-American women with breast cancer

A63 Background. Outcome disparities for African-American (AA) women with breast cancer may in part be due to biologically aggressive tumors, including more frequent p53 and basal (i.e. negative status for estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2) tumor subtypes. We hypothesized that survival would be worse for AA women with either p53 or basal subtypes. Methods. Tumors from 182 consecutive underserved AAs were evaluated for p53 and basal subtypes with immunohistochemistry, on paraffin embedded tissue. Univariate analyses were performed with the use of a two-sided log-rank test and multivariate analysis with the Cox proportional-hazards model. Survival was computed by the Kaplan-Meier method and correlated with tumor subtype. Results. A total of 55 (30.2%) and 62 cases (34.1%) were found to have p53 and basal subtypes. Young age (p=0.032; odds ratio [OR]=0.97, 95% Confidence Interval [CI]=0.943-0.997), high AJCC stage (p=0.0001; OR=3.38, 95% CI=1.768-6.454), high tumor grade (p=0.0001; OR=17.05, 95% CI=6.768-42.82) and positive p53 status (p=0.005; OR=2.54, 95%CI=1.315-4.887), were all significantly correlated with basal subtype. Adjustment for age and stage did not alter correlation of grade (p=0.0001; OR=14.05, 95%CI=5.69-37.05) and p53 status (p=0.007; OR=2.578, 95%CI=1.291-5.148) with basal subtype. At median follow-up of 40 months, univariate analyses showed that both p53 (p=0.033; Hazard Ratio [HR]=1.829, 95% CI=1.049-3.189) and basal (p=0.017; HR=1.9, 95% CI=1.126-3.27) subtypes were significantly correlated with worse survival. However after adjustment for age & stage, only p53 status (p=0.047; HR=1.755, 95% CI=1.007-3.061) remained significantly correlated with worse survival. Conclusions. Although as expected, p53 status was significantly correlated with basal subtype, only abnormal p53 expression was significantly correlated with poorer survival in multivariate analysis. These results suggest that p53 status is more likely than basal subtype to predict survival in AA women with breast cancer.