Cholelithiasis and carcinoma of the colon.

Cholelithiasis and carcinoma of the colon have similar geographic distributions and common dietary and chemical pathogenetic factors. A study was done to test whether an association between cholelithiasis and colonic cancer existed in the population of Rochester, Minnesota. During the period from 1950-1969, 2413 new cases of cholelithiasis were identified in this population. Because the age- and sex-specific prevalence rates of colorectal cancer in this population were also available, the authors calculated the expected number of cases of colorectal cancer at the time of diagnosis of cholelithiasis. The relative risk (observed/expected) of colonic cancer among persons of all ages and both sexes with cholelithiasis was 1.52 (95% confidence interval, 1.1-2.0). Although the association seems significant, there is a potential bias in that the identification of asymptomatic cases of cholelithiasis might be facilitated in patients who have an operation or frequent follow-up examinations for colonic cancer. When the analysis was repeated separately for symptomatic and asymptomatic cases of cholelithiasis, all the excess (and statistical significance) was confined to the asymptomatic group, and apparent confirmation of the suggested bias. Therefore, the authors believe that no real association exists between cholelithiasis and carcinoma of the colon.