Alcohol consumption has been investigated as a possible risk factor for ovarian cancer in several epidemiological studies, with inconsistent findings. Recent studies have suggested that the association between alcohol consumption and ovarian cancer may vary according to histologic subtype of ovarian cancer and type of alcohol consumed (e.g., wine, beer, or liquor). We examined these associations in a population-based case-control study comprised of 762 incident cases of epithelial ovarian cancer and 6,271 population controls from Massachusetts and Wisconsin aged 40-79 years. Women reported their usual alcohol consumption as young adults (20-30 years of age) and in the recent past. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. There was no significant association of ovarian cancer with increasing alcohol consumption either during ages 20-30 years (p trend 0.42) or in the recent past (p trend 0.83). Regular drinking of beer (1 drink/day or more) during ages 20-30 (OR 1.55, 95% CI 1.07-2.26), though not liquor (OR 1.35, 95% CI 0.86-2.11) or wine (OR 0.99, 95% CI 0.49-2.00), was associated with a statistically significant increase in risk of invasive tumors, whereas no significant relationships were observed for recent drinking, regardless of alcohol type. The elevated risk for early adult regular drinking was confined to serous invasive tumors (OR 1.52, 95% CI 1.01-2.30), though results for other subtypes were based on sparse data and results were imprecise. In this study, neither total alcohol consumption as a young adult nor recently was associated with an increase in the risk of ovarian cancer. ' 2006 Wiley-Liss, Inc.Key words: ovarian neoplasms; alcohol drinking; women; risk factorsThe etiology of ovarian cancer is poorly understood, and most established risk factors are related to reproduction. 1 Thus, there are limited opportunities for prevention of this often fatal cancer. Alcohol consumption, a common, potentially modifiable exposure, has been investigated as a possible cause of ovarian cancer in several epidemiological studies, with inconclusive findings. Many case-control studies have not shown a statistically significant association with alcohol consumption. 2-11 Of the 2 prospective cohort studies published, 1 found a statistically significant decreased risk with increasing alcohol consumption, 12 while the other 1 found no association. 13 Some recent studies have suggested that the association between alcohol consumption and ovarian cancer may vary by ovarian cancer histology [14][15][16] or by the type of alcohol consumed (e.g., wine, beer, or liquor). 14, 15 We evaluated these associations in a large population-based US casecontrol study in which we collected detailed information on alcohol consumption.
Material and methods
Study participants and designCases. Eligible women were enrolled in 2 case-control studies conducted in the populations of Massachusetts (excluding Boston) and Wisconsin. All English-speaking female residents, aged 40-79 (1993-1995) or aged 20-75 (1998-2...