The more alcohol a female consumes between her first menstrual cycle and her first full-term pregnancy, the higher her risk of breast cancer, according to a study published in the Journal of the National Cancer Institute.

Researchers analyzed the health history of 91,005 mothers with no history of cancer who were a part of the Nurses' Health Study II from 1989 to 2009.

The study was conducted by researchers from the Washington School of Medicine in St. Louis, Brigham and Women's Hospital, Harvard Medical School, Beth Israel Deaconess Medical Center and Harvard School of Public Health.

In 1989, all women in the study completed a questionnaire on their early alcohol consumption between the following age periods:

  • 15-17 years
  • 18-22 years
  • 23-30 years
  • 31-40 years.

The women were then analyzed over the 20-year period in order to determine their risk of breast cancer.

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Females who drink between their first menstrual cycle and their first full-term pregnancy may increase their breast cancer risk.

The analysis showed that over the full study period, 1,609 breast cancer cases were identified, along with 970 proliferative benign breast disease (BBD) cases.

Overall results of the study revealed that a female who averages one alcoholic drink per day between her first menstrual cycle and her first full-term pregnancy increases her risk of breast cancer by 13%.

The findings also showed for every beer, glass of wine, or alcoholic shot consumed on a daily basis, a young woman can increase the risk of proliferative benign breast disease by 15%.

The study authors add that although proliferative benign breast tumors are not cancerous, they can increase the risk of breast cancer by 500%.

Breast tissue 'susceptible' during adolescence

Dr. Graham Colditz, associate director for cancer preventions and control at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine, says:

"More and more heavy drinking is occurring on college campuses and during adolescence, and not enough people are considering future risk. But, according to our research, the lesson is clear.

If a female averages a drink per day between her first period and her first full-term pregnancy, she increases her risk of breast cancer by 13 percent."

According to the researchers, the cells in breast tissue are very susceptible to cancer-causing substances during adolescence and after.

They add that an area of concern is the length of time between the average age a girl begins her menstrual cycle, and the average age of a woman's first full-term pregnancy. The longer the length of time, the more they will drink.

"Reducing drinking to less than one drink per day, especially during this time period, is a key strategy to reducing lifetime risk of breast cancer," adds Dr. Colditz.

He adds that further research is needed to determine what can be done to mitigate the risk of breast cancer in young women if they choose to drink. At present, the researchers conclude that reducing alcohol consumption would be the best intervention.

Additionally, they add that school kids should be provided with more knowledge about the effects alcohol can have on breast cancer.

Ying Liu, first author of the study and a School of Medicine Instructor in the Division of Public Health and Sciences, says:

"Parents should educate their daughters about the link between drinking and risk of breast cancer and breast disease. That is very important because this time period is very critical."