Fruits and vegetables and endometrial cancer risk: a systematic literature review and meta-analysis.

Endometrial cancer is the most common female gynecological cancer in the United States. Although obesity is a well-established risk factor, the role of other dietary factors is not well understood. The purpose of this study was to summarize and quantify the current evidence for fruit and vegetable intake and endometrial cancer by conducting a systematic literature review and meta-analysis. Searches were conducted to identify relevant papers published up to June 2006 in various databases. We included peer-reviewed manuscripts published in any language. Random and fixed-effects pooled risk estimates were estimated. We found one cohort study and 16 case-control studies evaluating various aspects of consumption. The random-effects summary estimates (95% CI) comparing high vs. low categories of intake reported were 0.71 (0.55-0.91) for total vegetables based on 10 studies, 0.85 (0.74-0.97) for cruciferous vegetables based on seven studies, and 0.90 (0.72-1.12) for total fruit based on 14 studies. For 100 g/day intake, summary ORs were 0.90 (0.86-0.95) for total vegetables, 0.79 (0.69-0.90) for cruciferous vegetables, and 0.97 (0.92-1.02) for total fruit. Excluding studies not meeting certain quality criteria provided similar results. The current evidence, based solely on case-control studies, with less than half being population-based, suggests a modest inverse association with vegetable consumption, particularly for cruciferous vegetables. We did not find any cohort studies evaluating fruit and vegetables separately. No firm conclusion can be drawn at this time in the absence of additional well-conducted population-based studies and, particularly, prospective data.