Racial disparity of epidermal growth factor receptor (EGFR) expression in prostate cancer (PC)

Abstract

4556 Background: EGFR plays a critical role in signal transduction and is a target for a novel class of anticancer agents. Compared to other solid tumors, limited data are available regarding the clinical relevance of EGFR in PC and specifically the interethnic differences in EGFR expression. The latter has strong therapeutic importance, as interethnic variation in response to anti-EGFR agents has been recently reported. We investigated EGFR expression in a well-characterized cohort of PC patients with equal access to care to determine the associations between EGFR expression and 1) patients' ethnicity, 2) clinicopathological parameters, and 3) recurrence after surgery. Methods: Tumor tissues from 202 radical prostatectomy cases performed between 1990–2000 at the Veterans Administration Medical Center, NY were studied. EGFR expression was evaluated using an immunohistochemical assay (142 African-Americans (AA), 60 Caucasians, median age: 67; stage T2: 130, >T3: 72; Gleason 7: 92). EGFR expression was graded from 0 to +3. EGFR protein expression was classified into two categories: negative (0&1) and positive (2&3). Results: EGFR overexpression was observed in 75 of 202 (37%) cases. There was significant association between EGFR overexpression and AA race (P=0.0006), higher pretreatment PSA (P=0.02), and stage (P=0.02), but not with Gleason score (P=0.33). The association between AA race and EGFR overexpression remained significant in a multivariate model after controlling for grade, stage, and pretreatment PSA simultaneously (P=0.003). Sixty-six patients recurred during their follow up (median=4 years). EGFR overexpression showed a trend with PSA recurrence but the association was not statistically significant (P=0.07). Conclusion: Our data demonstrate a strongly significant ethnic difference in EGFR expression of PC patients. This suggests that patients' race should be considered in designing clinical trials using anti-EGFR agents. No significant financial relationships to disclose.