P. H. Lam1, I. D. Nwokeabia2, A. C. Obirieze3, S. C. Onyewu3, B. S. Li3, N. Enwerem3, G. Ortega3, T. M. Fullum3, W. A. Frederick3, L. L. Wilson3 1Cedars-Sinai Medical Center,Los Angeles, CA, USA 2Washington University,St. Louis, MO, USA 3Howard University College Of Medicine,Washington, DC, USA
Introduction: Black patients have the highest incidence and mortality rates of colon cancer when compared to other racial/ethnic groups. Screening rates for colon cancer are lower in black patients, and studies have shown varying anatomic locations of adenomatous polyps and colon cancers in these patients. Studying the location of these cancers within the colon could help tailor where to screen and which screening test to use. We aim to investigate the anatomic location of high-grade dysplasia from adenomatous polyp among black patients, using a national tumor registry.
Methods: The Surveillance Epidemiology and End Results database from 1973 to 2008 was utilized. We identified patients with a single primary diagnosis of a high-grade dysplasia arising from adenomatous polyp of the colon using appropriate ICD-O-3 codes. Age and gender-adjusted proportions of proximal vs. distal lesion location were derived for all patients using multivariable regression analysis.
Results: A total of 18,762 patient records, comprising 16,276 (86.8%) white and 2,486 (13.2%) black patients, met the study criteria. The incidence of high-grade dysplasia of the colon has been increasing in black patients over the last three decades (9.9%, 13.0%, and 15.1% for 1973-1989, 1990-1999, and 2000-2008, respectively).
The most common location in the proximal and distal colon was the cecum (16.6%) and sigmoid colon (48.5%). Most patients had distal lesions (60.0%), most of which occurred at the sigmoid colon (48.5%). On multivariate analysis, black patients were 33% less likely to have a distal lesion compared to white patients (OR: 0.67, p<0.001, 95% CI: 0.61-0.73).
Black patients were more likely not to undergo surgery (4.9% vs. 3.3%), more likely to undergo partial or hemicolectomy (38.3% vs. 33.5%), or total colectomy (1.9% vs.1.3%), but less likely to undergo local excision with pathology (47.1% vs. 51.9%) (all p<0.001).
Conclusion: Black patients have increasing incidence of high-grade dysplasia arising from adenomatous polyp, lower likelihood of distal lesions of the colon, and more likely not to undergo surgery. This suggests their importance for screening with colonoscopy. Nonetheless, more research on the use of different screening tests, location of cancer found, and surgical preferences among different race/ethnic groups are needed.