Background: Colorectal adenomas are clear precursors of cancer; hyperplastic polyps have recently been hypothesized to also have malignant potential. However, these two distinct colorectal lesions are probably on different molecular pathways to neoplasia. An inverse association between vitamin D and adenoma risk has been reported, but this is the first study, to our knowledge, that examines circulating 25(OH)D in relation to risk of hyperplastic polyps.

Methods: We conducted a colonoscopy-based case-control study of adenomas and hyperplastic polyps among 474 members of a large integrated health plan. Self-administered questionnaires provided data on demographics and colorectal polyp risk factors, and we assayed plasma samples donated by participants at the time of the colonoscopy for total 25-hydroxyvitamin-D (25(OH)D) concentration. Polytomous regression was used to estimate separate odds ratios for adenomas (n = 153) and hyperplastic polyps (n = 91) by tertile of 25(OH)D.

Results: An inverse association between 25(OH)D and adenomas was observed (comparing upper to lower tertiles: adjusted OR [95%CI]: 0.60 [0.34-1.08]). After restriction of the analyses to study participants with no history of polyps, this OR estimate moved further from the null and became statistically significant (adjusted OR [95%CI]: 0.43 [0.20-0.96]). In comparison, no statistically significant association between hyperplastic polyps and 25(OH)D was observed among the full study participants (adjusted OR [95%CI]: 1.12 [0.59-2.13]) nor among those without prior polyps (adjusted OR [95%CI]: 1.27 [0.57-2.35]).

Conclusions: There is no evidence in our study that the established inverse association between circulating 25(OH)D and colorectal adenoma applies to hyperplastic polyps.

This abstract is one of the 17 highest scoring abstracts of those submitted for presentation at the 34th Annual Meeting of the American Society of Preventive Oncology, to be held March 20-23, 2010 in Bethesda, MD.