Systematic review on "vitamin E and prevention of colorectal cancer"

Colorectal cancers (CRC) are highly prevalent cancer all over the world and need appropriate and timely prevention and treatment. Since years it has been argued that antioxidant vitamins have a potential role in the prevention of several neoplasm including colorectal cancer though the answer remained controversial. Most of the observational studies in past have shown that Vitamin E has some protective effect in the primary prevention of colorectal cancer, however its exact role is not yet established. On the other hand recently conducted experimental studies have shown variable results regarding the role of vitamin E in preventing colorectal cancers. Thus this review was conducted to study the role of vitamin E in preventing colorectal neoplasm. This review study was conducted from September 2008 to February 2009. We searched multiple electronic sources including (PUBMED) MEDLINE, Cochrane Database for identifying existing Systematic Reviews, OVID data base and other library sources to identify relevant studies for this review. Data was collected using data extraction form. Meta analysis was performed in Review Manager version 4.3. We identified four trials on vitamin E role for primary prevention of CRC, includes 94069 participants (47029 in vitamin E Vs 47040 in placebo), aged 40 years or above, who were randomized to vitamin E supplement versus placebo. The outcome measure in our review was incidence of colorectal cancer in the follow up period of 7 to 10 years. We found no sufficient evidence of vitamin E role for decreasing risk of CRC incidence (RR: 0.89, CI: 0.76, 1.05; p-value = 0.18). It has been identified in the review that Vitamin E does not have protective role in the prevention of colorectal cancer. Further studies on diverse population are required to determine the role vitamin E for the primary prevention of colorectal cancer.