Men with Prostate Cancer Are Predisposed to Colon Cancer: Half a Million US Veterans' Case Control Study

Men with Prostate Cancer Are Predisposed to Colon Cancer: Half a Million US Veterans’ Case Control Study Vikas Khurana, Hanmanth R. Bejjanki, Jeffrey A. Goldstein, Gloria Caldito, Charlton Fort, Ruby Kochhar Background: Prostate and colorectal cancers share some common risk factors including age, family history and a diet high in fat. For both cancers the screening for general population starts at age 50. Several studies were done to evaluate the association between them, however the results have been conflicting and inconclusive. Aim: To study the association between prostate and colorectal cancers and to evaluate the effect of prostate cancer diagnosis on the risk for colorectal cancer. Design: VISN 16 data warehouse, which contains clinical and demographic information about all veterans (O1.4 million patients) cared for at the 10 VA Medical Centers in 4 states comprising the South Central VA health Care Network in the mid-south region of the US, was queried from Oct 1998 to June 2004. Patients with prostate cancer were identified using ICD-9 (185) codes and patients with colorectal cancers were identified using ICD-9 (153 & 154) codes. Retrospective case control design was used. Multiple logistic regression analysis was used with calculation of odds ratios and 95% confidence intervals were used universally. Statistical analysis was performed using SAS software version 9.0 (Chicago, IL). Results: We analyzed 443,774 male patients from our database. The mean age of the selected group was 62.5(S.D. G 14.5). There were 26,087 (5.88%) prostate cancer and 5423 (1.22%) colorectal cancer patients in the study group. There was a significant increase in the incidence of colon cancer in patients diagnosed with prostate cancer compared to patients without prostate cancer (Odds Ratio 1.79, 95% CI 1.65 to 1.93 p-value ! 0.0001) after the data was controlled for the above covariates. Discussion: The increased incidence of colon cancer in patients with prostate cancers may be due to several risk factors that are common to both prostate and colon cancers. The data should be evaluated with caution given the limitations of the population, the database and the design of the study. Some factors known to increase the risk of colorectal cancers like family history, diet and inflammatory bowel disease were not incorporated into the study. Conclusion: Our data suggest that prostate cancer is a significant risk factor for colorectal cancer. Patients with prostate cancer may be considered for more aggressive screening for colorectal cancer. Abstracts