Abstract 5516: Race, age and advanced stage colorectal cancer survival

Abstract

Abstract African Americans (AA) have worse stage-specific survival from colorectal cancer (CRC) compared to European Americans (EA), but the reasons for these differences are not well understood. To address this gap in understanding, and to examine racial differences in survival of patients with metastatic colorectal adenocarcinoma (mCRC) by age and prognostic tumor characteristics, we analyzed clinical data from Hollings Cancer Center (HCC) at the Medical University of South Carolina. Because metastatic disease has standard recommendations, a large racial difference in relative survival, and a documented change in chemotherapy usage in 2004, the dataset from HCC is ideal for this analysis. Data were collected by systematic medical record audits of patients diagnosed at HCC between June 2004 and June 2008 with follow-up through June of 2010. Analyses were designed to compare AA to EA by computing medical survival and hazard ratios (HR) and 95% CIs to model the hazard of death as a function of race, controlling for age, sex, and first-line chemotherapy treatment. We also assessed the interaction between race and age and race and clinicopathogic characteristics (i.e. histologic type, location, and grade) and their impact on survival. All tests of statistical significance were two-sided. Data from 82 (27 AA and 55 EA) patients with mCRC were evaluated. Overall survival between AA and EA differed by age, with the racial difference in survival most pronounced among younger (61 years - below the median) compared to older (≥ 61 years - above the median age) patients. Median survival among younger EA and AA was 31 months (95% CI 17-35 months) and 13 months (95% CI 6-17 months), respectively; among older patients, median survival for EA and AA was 22 months (95% CI 8-32 months) and 12 months (95% CI 3-α), respectively. In the younger group, AA had a 2.65 (95% CI 1.24-5.66) times greater risk of death than EA whereas in the older group there was no significant difference (HR 0.93 95% CI 0.39-2.21), a statistically significant interaction (p<0.03). Among the younger CRC cases, AA were more likely than EA to present with mucinous, lower-grade, and colonic carcinomas, even though the AA patients were more likely to die from non-mucinous (p for interaction = 0.04), rectal (p for interaction = 0.06), and higher-grade (p for interaction = 0.12) tumors. In conclusion, the overall poorer survival among AA was concentrated in the younger patients. Despite being less prevalent at diagnosis, the results also indicated that rectal location, non-mucinous histology, and higher tumor grade were associated with poorer survival among the young AA. The reasons for the overall racial disparity being concentrated in the younger patients in unexplained; future studies may consider the role of pathomolecular markers, medical comorbidities, and treatment-related factors to further elucidate etiologies of the disparities seen in younger AA. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5516. doi:1538-7445.AM2012-5516