Colorectal Cancer: Descriptive Analysis Comparing a Native African Population to an African American Population

Abstract

Introduction: The ACG recommends colorectal cancer (CRC) screening at an earlier age (45 years) in the African-American (AA) population. However, there is limited data comparing the African-American population to the native African population. Therefore, we compared the trends of CRC in a native African (NA) and African-American populations using the SEER database and the local cancer disease hospital (CDH) registry. Methods: A retrospective analysis of the CDH database in Zambia, Southern Africa and SEER database. All medical records of patients with CRC were retrieved and manually reviewed. A data collection tool and master sheet code created a priori were used. We extracted gender, age, time of presentation, mode of diagnosis, stage at diagnosis, treatment and outcome. For the African-American population, we extracted CRC data from the SEER database. Data was analyzed using SAS. Descriptive statistics in the form of frequency distributions or sample means and standard deviations as well as Spearman correlations for year/gender, year/stage and year/age were found. We used a T-test to compare subjects between Zambia and USA. A p-value < 0.05 was considered significant. Results: 377 charts were identified in the CDH database between 2007 and 2015 with 234 meeting inclusion criteria for the final analysis. The mean ages were 48.6 years for the Zambian group, 69.4 years for SEER group, and 65.6 years for only AA SEER group. The difference is highly significant in both cases (p < 0.0001). In the Zambia sample, 62% are males, which is significantly higher than all SEER (51%, p=0.0008) and higher than only AA SEER black (48%, p < 0.0001). Using descriptive analysis for patterns in the Zambian group: mode of diagnosis was surgical in 195 subjects (84%), histology adenocarcinoma in 225 (96.5%), most common location is rectum 124 (53%) followed by sigmoid 31 (13.4), and cecum 26 (26%). 122 subjects (54%) were Stage 4 at diagnosis. A trend test shows no difference across years relative to the proportions of male/female (p=0.56). Using the Spearman Rank correlation, we see no association between Year and Stage (p=0.30) or Year and Age (p=0.92). Conclusion: Colorectal cancer occurs at a significantly younger age in the native African population when compared to an African-American population. Further studies are necessary to elucidate risk factors which could help develop screening protocols and understand the pathway of cancer development.