Diverticular disease in patients with colon cancer: Subgroup analysis of National Surgical Adjuvant Breast and Bowel Project protocol C-06

Background: Similar epidemiologic characteristics suggest a common etiology for colon cancer (CC) and diverticular disease of the colon (DD). The relationship between the 2 diseases is still unclear, and the impact of DD in patients diagnosed with CC on disease-free survival (DFS) and overall survival (OS) is unknown. National Surgical Adjuvant Breast and Bowel Project (NASBP) protocol C-06 is a clinical trial comparing oral uracil/tegafur/leucovorin with 5-fluorouracil/leucovorin in patients with resected stage II/III carcinoma of the colon. Patients and Methods: The NASBP enrolled 1608 patients who had undergone potentially curative resection for stage II/III colon cancer from 256 medical sites between February 14, 1997, and March 31, 1999. Results: Pathology reports from 1561 eligible patients retrospectively reviewed for the presence of DD revealed that 160 (10.2%) had this disease. The median ages of patients with CC and DD and without DD were 67 and 61 years, respectively (P < 0.05). The majority of patients were white, and Hispanic patients were better represented in the group with DD (P < 0.05). Colon cancer was located in the rectosigmoid in 46.88% of patients with DD and in 31.92% of patients without DD (P < 0.05). A baseline diagnosis of DD made no significant contribution to DFS or OS without adjustment for confoundin factors (P = 0.2 and P = 0.32, respectively) or adjusted for Dukes classification and age (P = 0.49 and P = 0.68, respectively). Conclusion: The prevalence of DD in patients diagnosed and treated for CC was 10.2%. Patients with CC with and without DD differed from each other with respect to age, tumor location, and ethnicity. There was no negative impact of having DD on DFS and OS in patients treated for stage II/III CC.