Disparities in the Incidence of Colon Cancer: Do Anatomical Sites of the Colon Matter?

Abstract

Disparities in the Incidence of Colon Cancer: Do Anatomical Sites of the Colon Matter? James C. Hobley, Thomas J. McGarrity, Eugene J. Lengerich Background: Cancer remains the second leading cause of death in the U.S. Some reports reveal that approximately 30% of all cancer deaths associated with risk factors that are modifiable. African-Americans have rate of death from colorectal cancer (CC) that is higher than any other racial or ethnic group in the U.S. For both black men and women, CC ranks third as the leading cause of cancer death. Emerging literature suggests that there are biological, genetic, and treatment differences between right-sided and left-sided colonic lesions. Aim: To assess the temporal and racial differences in the incidence of cancer at anatomical sites of the colon. Methods: 1997-2001 data from Pennsylvania’s population-based cancer registry were used to calculate adjusted and unadjusted rates (and 95% confidence intervals) of site-specific colon cancer incidence by age groups and race. In the analysis, data for three-year periods were combined to increase the stability of site-, raceand age-specific rates. Results: Cancer of the cecum was more common among blacks than it was among whites; however the ratio of black/white rates was found to be decreasing with time (1997-99, 1.32; 1998-00, 1.31; 1999-01, 1.21). For those 70-74 years of age, the black/white ratio of cancer of the cecum has been steadily decreasing with time (1997-99, 1.72; 1998-00, 1.48; 1999-01, 1.12). The rate ratio for cancer of the cecum was greatest among the youngest adults who are generally recommended for screening (50-54 years of age) (1999-01, 2.45). For cancer of the ascending colon, the ratio of black/white rates was smaller and has increased recently (1997-99, 1.01; 1998-00, 1.16; 1999-01, 1.13). Conclusions: It was possible that different risk factors were affecting the incidence of site-specific colon cancer. Within the more proximal colon that is screened with colonoscopy or double contrast barium enema, rate ratios and time trends appear different: among blacks, the incidence of cancer of the ascending colon increased with time and the incidence of cancer of the cecum decreased. Further evaluation of risk factors for colon cancer should be pursued in effort to understand the cause of these observed disparities. Findings from such studies may then allow proper clinical correlation that may contribute to the elimination of the disparity that exists in colon cancer incidence between blacks and whites. W1110 The Usefulness of Preoperative CT Colonography to Evaluate the Proximal Colon Kyu Chan Huh, Hyun Ju Yoon, Sun Moon Kim, Tae Hee Lee, Euyi Hyeog Im, Young Woo Choi, Dong Jin Jung, Won Jun Choi, Young Woo Kang Background/Aims: It is important to know the proximal portion lesion of occlusive colon cancer, in order to choose proper management and decide the resectional margin. CT colonography has emerged as an alternative method for patients undergoing full structural screening of the colorectum. The aim of the study is to evaluate the usefulness of preoperative CT colonography to exam the proximal colon in patients with distal occlusive carcinoma which could not be passed endoscopically. Method: This is a prospective study. Thirty-five patients with occlusive colorectal carcinoma diagnosed by conventional colonoscopy underwent preoperative CT colonography with the use of standard protocol. Their average age was 61 years old, and 20 were men and 15 were women. We performed the follow-up conventional colonoscopy within 1 month after surgical operation to compare the lesion of CT colonography. Result: A total of 27 cases out of 35 patients showed the same results from CT colonography and conventional colonoscopy. The concordance rate was 77% of CTcolonography and conventional colonoscopy in the detection of neoplastic lesion at proximal portion of obstructive colon cancer. Six polyps were found in 4 patients using conventional colonoscopy alone. Colonoscopy identified 2 polyps with a diameter of 5 mm or less and 4 polyps with a diameter of 5 mm to 10 mm. Otherwise, 3 polyps were found in 3 patients through CT colonography alone. All of them were identified with a diameter of 5 mm or less. Only 1 case showed different findings using conventional versus CT colonography, based on its size and site. Conventional colonoscopy detected a 10 mm sized polyp from the ascending colon, whereas CT colonography revealed a 3 mm sized polyp on the transverse colon. Conclusion: Almost mismatched colon polyps were not clinically important in its size. CT colonograpy can be considered a feasible and useful method to preoperatively evaluate the proximal colon in patients with distal occlusive carcinoma.