The cell and animal studies of red wine have examined effects in several cancers, including leukemia, skin, breast, and prostate cancers. Scientists are studying resveratrol to learn more about its cancer preventive activities. Recent evidence from animal studies suggests this anti-inflammatory compound may be an effective chemopreventive agent in three stages of the cancer process: Initiation, promotion, and progression.
Research studies published in the International Journal of Cancer show that drinking a glass of red wine a day may cut a man's risk of prostate cancer in half and that the protective effect appears to be strongest against the most aggressive forms of the disease. It was also seen that men who consumed four or more 4-ounce glasses of red wine per week have a 60 percent lower incidence of the more aggressive types of prostate cancer.
However, studies of the association between red wine consumption and cancer in humans are in their initial stages. Although consumption of large amounts of alcoholic beverages may increase the risk of some cancers, there is growing evidence that the health benefits of red wine are related to its nonalcoholic components.
This answer is based on source information from the National Cancer Institute.