Teen drinking among girls increases chance of breast cancer by one third Researchers led by Dr Ying Liu from Washington University School of Medicine in St Louis, US, examined the history of 91,000 women aged 15 to 40, The evidence suggested that alcohol consumed before first pregnancy may play an important role in the development of breast cancer, said the researchers. "Reducing alcohol consumption during this period may be an effective prevention strategy," they concluded. The findings indicated a dose-dependent relationship, which means the more alcohol a woman drinks during that time, the higher her risk of developing breast cancer. Dr Liu said: "The general consistency in the patterns of association between alcohol and risk of proliferative benign breast cancer disease and of breast cancer lends support to the hypothesis that alcohol intake, particularly before first pregnancy when breast tissue is likely at its most vulnerable stage, may play an important role in the etiology of breast cancer." She added: "These findings have potentially important implications for breast cancer prevention." Professor Paul Pharaoh, Professor of Cancer Epidemiology, University of Cambridge, said: What we already know is that in a rather general sense drinking alcohol is associated with an increased risk of breast cancer and that the more a woman drinks the greater the risk. What we did not know: whether drinking alcohol at different ages has greater or lesser effects. Of particular interest is the time between puberty (menarche) and first pregnancy, when the breast tissue might be particularly susceptible. The figures were collected using questionnaires as part of the Nurses' Health Study II (NHSII). Alcohol consumption in four age periods were obtained by asking participants about the total number of alcoholic drinks consumed at different ages: 15-17, 18-22, 23-30, and 31-40. Among these women, 1,609 cases of breast cancer and 970 cases of BBD occurred during the study period. Previous research has found that women who drink are more likely to develop many sorts of cancers compared with those who are teetotal. As well as increasing the risk of breast cancer, it also increases the chance of disease of the liver, mouth, throat and oesophagus. Research has yet to establish why drinking alcohol seems to increase breast cancer risk. Studies have suggested that alcohol can increase oestrogen levels which could trigger hormone-receptor-positive types of the disease.