I am a breast cancer survivor and have been told by my oncologist to stay away from alcohol (or drink it rarely) because alcohol is a carcinogen and could cause a recurrence. What is the data on this? How afraid should I be of alcohol?
—Andrea
The relationship between alcohol and breast cancer is well studied. For many years, researchers have noted that alcohol consumption is associated with breast cancer risk. I am cautious about making the leap from association to causation, but as the paper above outlines, additional research has been done to understand the relationship between breast cancer and alcohol consumption.
Several studies have found that the risk of breast cancer increases with increased alcohol consumption. This is often referred to as a dose response. As the dose of alcohol is increased, the effect — in this case, risk for breast cancer — is increased.
Additionally, the authors outline two possible ways alcohol increases risk for breast cancer. First, they note that the metabolism of alcohol results in chemicals that increase stress on a cellular level. That stress can result in damage to cells that can lead to the type of mutations that cause cells to grow and multiply in an unregulated way. In this way alcohol consumption has been associated with a number of different cancers, not just breast cancer.
Secondly, alcohol consumption has been shown to increase estrogen levels in the blood. Increased estrogen would be expected to act specifically on the subset of breast cancers that grow in response to estrogen. And in fact, alcohol consumption is associated with increased risk for estrogen-receptor-positive breast cancers.
These studies all look at the risk of breast cancer among all women (regardless of their history of breast cancer). However, women who have already survived breast cancer are typically at increased risk of recurrence.
So what does the data say specifically about the increased risk of alcohol consumption on the risk of recurrence of breast cancer?
In a review of 16 studies including more than 35,000 women regarding the effects of breast cancer risk among women with a history of breast cancer, the association is not as clear. The strongest association the authors found was in postmenopausal women, where increased alcohol consumption was associated with a 20% to 50% increased risk for recurrence. So if you are postmenopausal and have a 10% chance of recurrence — there are validated tools for calculating your risk of recurrence — alcohol consumption might increase your risk to 12% to 15%.
The takeaway: There is an association between alcohol intake and breast cancer, and there are plausible mechanisms for how increased alcohol might cause an increased risk of breast cancer. The association between alcohol consumption and breast cancer recurrence is less clear, but alcohol may be associated with as much as a 50% increased risk of breast cancer recurrence in postmenopausal women. Ultimately, though, we need better data to definitively answer this question.
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