High Vitamin D Levels Linked to Reduced Risk for Colon Cancer

From MedscapeCME Clinical Briefs

News Author: Laurie Barclay, MD
CME Author: Charles P. Vega, MD

CME Released: 02/09/2010;

February 9, 2010 — High vitamin D levels are linked to lower risk for colon cancer, according to the results of a nested case-control study reported Online First in the January 22 issue of the BMJ.

"An effect of vitamin D on cancer may be important in the colorectum because both normal and neoplastic colon cells can produce the active hormone from the main circulating form 25-hydroxy-vitamin D(25-(OH) D), suggesting that it may play a direct role in controlling the growth of normal and neoplastic colonic cells," write Mazda Jenab, from the International Agency for Research on Cancer (IARC-WHO), in Lyon, France, and colleagues. "However, the epidemiological evidence is not conclusive and almost no pre-diagnostic data are available from European populations."

The goal of this study was to evaluate the association between prediagnostic circulating vitamin D concentration, dietary intake of vitamin D and calcium, and the risk for colorectal cancer in European populations, using the European Prospective Investigation into Cancer and Nutrition (EPIC) study cohort of more than 520,000 participants from 10 western European countries. After enrollment into the EPIC cohort, incident colorectal cancer developed in 1248 patients, and these case patients were matched to 1248 control subjects.

Primary study endpoints were circulating vitamin D concentration (25-[OH]D) measured by enzyme immunoassay, and dietary and lifestyle data collected with questionnaires.

Although higher dietary intake of calcium was associated with a lower risk for colorectal cancer, dietary vitamin D intake was not associated with disease risk. Sex, season, and month of blood donation did not affect the findings

BMJ. Published online January 22, 2010. Abstract

Clinical Context

Although epidemiologic research has suggested an inverse relationship between calcium and vitamin D and the risk for colorectal cancer, an analysis of the Women's Health Initiative cohort by Wactawski-Wende and colleagues suggested that oral supplementation of calcium and vitamin D might not ameliorate the risk for colorectal cancer among women.
Specifically, the results of the study, which were published in the February 16, 2006, issue of the New England Journal of Medicine, found that daily calcium supplements at a dose of 1000 mg with vitamin D3 400 IU were not superior to placebo in reducing the risk for colorectal cancer. This result was unchanged on subgroup analysis.

In addition to being consumed through the diet, vitamin D is synthesized through sun exposure. The current study focuses the association between circulating levels of vitamin D, in the form of 25-(OH)D, diet, and the risk for colorectal cancer in a large cohort of European adults.