A study involving 61,084 Swedish women (38-76 years old) resulted in 266 who were diagnosed with ovarian cancer during the 13.5-year study period. The diets of these cancer patients were examined for intake of dairy products and lactose and then compared to the non-cancer controls.
A review of their diet found women who consumed 4 or more servings of dairy per day had twice the risk of serious ovarian cancer compared to women who consumed less than 2 servings of diary per day. Dietary milk showed the strongest effect: intakes of 2 or more glasses of milk were associated with double the risk of serious ovarian cancer compared with the "never or seldom" milk-intake group.
Am J. Clin. Nutr. 2004;80:1353-7