In all, 147 participants reported having benign breast disease, with 67 cases having been confirmed by biopsy.
When Berkey and her colleagues looked at the diagnoses of benign breast disease and drinking, they found that risk for benign breast disease rose along with the frequency of alcohol consumption: from a 1.5 increased risk for drinking one or two days per week, to a three times greater risk for those drinking three to five days per week, and to a 5.5 times greater risk for drinking six or seven days per week, when compared with those who never drank or who drank less than once per week.
Even once-a-week drinkers may not be absolutely safe, Berkey noted. "I suspect there may be some small additional BBD risk for even small amounts of alcohol consumed during adolescence," she said.
Teen years are a critical time for potential cancer-producing exposures, she said, because the mammary glands are undergoing rapid growth during that period.
Berkey said she suspects the link is due to alcohol increasing total estrogen levels, raising the likelihood of benign breast disease.
"For me, this is not a surprise," said Dr. Patricia Ganz, director of cancer prevention and control research at the Jonsson Comprehensive Cancer Center at the University of California, Los Angeles. Regular alcohol consumption is known to increase a woman's risk for both breast cancer and benign breast disease, she said, and "certain forms of BBD increase the risk of breast cancer."
And though she described the new study as excellent, she cautioned that the sample size was relatively small.
"I wouldn't scare [teens] and say, 'You are going to get breast cancer if you drink,'" Ganz said. But, on the other hand, she added: "The public health message is, these young girls shouldn't be drinking anyway."
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