P53 expression in breast cancer is more likely to predict survival in African-American than Hispanic or white women

Abstract

10001 Background: Abnormal nuclear accumulation of p53 protein may predict poorer survival & aggressive tumor biology in African-American (AA) women with breast cancer. We hypothesized that compared to Hispanics or whites, survival would be worse for AA women with p53 positive tumors. Methods: Tumors from 195 consecutive AA, 46 Hispanic & 52 white women were evaluated for p53 expression with IHC, using antibody Pab1801 on paraffin embedded tissue, at the SHCC MBCCOP, in Chicago. Staining was scored on the UK Receptor Group 0–8 system with score ≥2 read as positive. Survival was computed by the Kaplan-Meier method & correlated with p53 expression. Univariate analyses were done with two-sided log-rank test & multivariate analysis was done with Cox proportional-hazards model. Results: There were no significant differences between racial groups regarding tumor size, grade, node status, stage, estrogen receptor (ER) status, treatment & p53 expression. Hispanics were significantly younger (p=0.014). For AA, Hispanic & white women respectively, p53 expression was 29.2%, 34.8% & 18.8%. High grade (p=0.0001) & negative ER status (p=0.006) were significantly associated with p53 expression in AA women; similar results were seen in whites (p=0.014 & p=0.031 respectively), however although the trend for grade was similar, only negative ER status was significantly associated with p53 expression in Hispanics. AA women with p53 positive tumors had significantly worse survival compared to AA women with p53 negative tumors (Hazard Ratio=1.945; 95% CI=1.040–3.638; p=0.037). However, comparison of survival between races for women with p53 positive tumors (p=0.793) and also for women with p53 negative tumors (p=0.4027) was not different. Multivariate analysis demonstrated that there was no interaction (p=0.523) between p53 expression & stage as predictors of poor survival in AA women. Conclusions: Analyses between racial groups demonstrated that AA, Hispanic & white women with breast tumors with abnormal p53 expression had similar associations with high tumor grade, negative ER status and survival. However within racial groups, abnormal p53 expression was only able to predict significantly worse survival in AA women. This association appeared to be independent of stage. [Table: see text]