Does the Location of Adenoma At Baseline Predict the Location of Subsequent Recurrence? Evidence from the Polyp Prevention Trial

Abstract

Background: Studies have suggested possible biological differences between proximal and distal colon neoplasia. There is limited prospective data on the role of location in colorectal carcinogenesis. Aim: To examine whether the baseline location of adenoma predict the location of subsequent recurrence. Methods: The Polyp Prevention Trial was a 4-year, multicenter, randomized control trial which evaluated the effect of a low fat, high fiber, fruits and vegetable diet on the risk of colorectal adenoma recurrence. A total of 1,864 participants had complete information on the location of their baseline adenomas and completed the trial. We examined the association between baseline adenoma location on subsequent distal (rectosigmoid to splenic flexure) and proximal (transverse colon to cecum) adenoma recurrence. We used multinomial regression models to estimate the Relative Risks (RR) and 95% confidence intervals (CI). Results: A total of 1,131 (60.7%) subjects did not have adenoma recurrence while 733 (39.3%) subjects had adenoma recurrence (228 distal only; 369 proximal only; and 136 in both distal and proximal colon). Overall, given adenoma recurrence, there was a tendency towards a proximal shift (Table). In multivariable analysis with adjustment for age, sex, body mass index, family history of colorectal cancer and use of non-steroidal anti-inflammatory drugs, subjects with only proximal adenoma at baseline were less likely to have only distal adenoma recurrence (RR = 0.69; 95% CI: 0.47-1.00), but were more likely to have proximal adenoma recurrence (RR = 1.58; 95% CI: 1.20-2.09). Participants with proximal and distal adenomas at baseline were more likely to have adenoma recurrence in both locations: (RR = 1.61; 95% CI: 1.11-2.33) for distal only and (RR = 2.11; 95% CI: 1.53-2.90) for proximal only adenoma recurrence. Conclusions: Our study suggests a proximal shift of metachronous adenomas and subjects with adenomas in both distal and proximal colon are at the highest risk of adenoma recurrence.