A case-control study of milk-drinking and ovarian cancer risk

It has been hypothesized that milk consumption increases the risk of ovarian cancer because of a possible association of lactose with human ovarian failure. Milk is also a source of animal fats in the diet, and animal fat intake is associated with ovarian cancer risk. To explore further the possible confounding of the milk-ovarian cancer association by the animal fat content of milk, the authors performed a case-control study of 303 ovarian cancer cases and 606 age-matched nonmalignant-disease controls seen between 1982 and 1988 at Roswell Park Memorial Institute in Buffalo, New York. Total frequency of usual milk intake was not associated with increased risk. Usually drinking more than one glass of whole milk daily relative to never drinking whole milk was associated with a relative risk of 3.1 (95% confidence interval (CI) 1.8-5.5). Consumption of reduced-fat milk was associated with reduced relative risk. Among persons who reported drinking milk regularly, persons reporting drinking only whole milk were at increased risk (relative risk = 2.6, 95% CI 1.7-4.0) relative to persons who drank only skim milk or 2% milk. These findings suggest that milk-drinking is not a source of ovarian cancer risk independently of its fat content. Additional study of lactose and ovarian cancer risk involving careful control for confounding is needed.