Study: Does light alcohol consumption affect your breast cancer risk?

IN DEPTH REVIEW OF RESEARCH

Study background:

Alcohol is a carcinogen (something that is capable of causing cancer), and the International Agency for Research on Cancer has confirmed a relationship between alcohol and breast cancer. However, because the link between “light” alcohol consumption and breast cancer is still controversial, Kevin D. Shield and his colleagues from the Section of Cancer Surveillance published research in Alcoholism: Clinical and Experimental Research in June 2016 to better understand this relationship.

Researchers of this study wanted to know:

Is “light” drinking a contributor to breast cancer occurrence and mortality?   

Population(s) looked at in the study:

The study researchers pooled data together from two databases: GLOBOCAN 2012 for the estimated number of breast cancer cases by age, sex, and country; and the Global Information System on Alcohol and Health for alcohol consumption information. Researchers then developed a model that combined the information from both databases to model the alcohol consumption for the population. They used a method called Population-Attributable Fraction to determine the amount of breast cancer cases and mortality that were due to alcohol consumption.

Study findings: 

1. About 9% (144,000) of global breast cancer cases result from alcohol consumption.
   • About 61% of this group is 60 years old or younger.
   • About 19% of this group consists of women who were considered “light” drinkers (less than two drinks per day).
   • Breast cancer cases were most common in Northern and Western Europe.
2. About 7% (38,000) of global breast cancer deaths result from alcohol consumption.
   • About 50% of this group is 60 years old or younger.
   • About 18% of this group consists of women who were considered “light” drinkers (less than two drinks per day).
   • Breast cancer mortality was most common in Central and Eastern Europe.

Limitations:

Because researchers used secondary data—they didn’t collect it themselves—they weren’t able to ask questions about alcohol consumption, or control for other issues or factors that they might have wanted to know. Additionally, they were unable to assess how “light” drinking affected women who are already at higher risk of breast cancer (due to BRCA mutations, for example). And while the researchers were able to look at the percentage of breast cancer incidence and mortality for patients 60 years old and younger and patients older than 60 years, they did not break up the age groups further (for example, 40-49, 50-59, etc.). Finally, their computer modeling does not take into account the cancer burdens between different populations, such as people from a lower socioeconomic group (where research has shown an increased breast cancer mortality) or between different ethnic groups.

Conclusions:

This study suggests that “light” drinking does result in breast cancer occurrence and mortality for some people. While this study relied on previously collected data and estimates from a computer program to develop these results, considerable prior research has established the link between alcohol consumption and breast cancer. The Dietary Guidelines for Americans suggests women drink no more than one alcoholic drink per day.  Women should try to follow this recommendation, and to keep in mind that consuming one drink will not cause cancer. Cancer is complicated and caused by multiple factors, many of which cannot be controlled.

06/21/16