According to the 2019 National Survey on Drug Use and Health (NSDUH) report, 85.6% of people in the United States who are 18 or older had consumed alcohol at some point in life.
51% of women reported that they consumed alcohol in the past month.
Breast cancer is the most common type of cancer affecting millions of women globally. In the United States, 1 in every eight women will develop invasive breast cancer in her lifetime.
There are few reasons why researchers think alcohol consumption is related to breast cancer.
- The role of acetaldehyde (AA)
When a person consumes alcohol (ethanol), it goes through multiple detoxification pathways and uses several enzymes. One such enzyme is alcohol dehydrogenase (ADH). ADH converts ethanol to AA. AA is carcinogenic (cancer-causing) and needs to be quickly eliminated from the body.
While ADH is primarily expressed in the liver, it is also found in small quantities in the breast tissue. ADH converts ethanol into AA in the breast tissues and causes abnormal DNA changes, leading to breast cancer.
- Increased estrogen levels
Alcohol can increase estrogen levels in the body. A particular study reported that when compared to women who don’t drink, pre-menopausal women who drink have an 18% increase in serum estrogen levels.
The body uses CYP enzymes to clear out excess estrogen from the body. These enzymes convert estrogen into intermediaries that are then removed from the body. This conversion process releases free radicals that can cause cell DNA abnormalities and increase the risk of cancers, including breast cancer.
Higher levels of estrogen in the body can also increase the activity of the Estrogen Receptor α (ERα) protein. This protein attaches itself to the DNA and controls various genes. Increased ERα activity leads to increased cell division and growth (cell proliferation), increasing the chance of cell damage and resultant cancer.
Alcohol And Breast Density Marker
Breast density or mammographic density is a measure of the type of tissues that make up the breasts. Breasts contain fat tissues, glandular tissues (tissues that help make breast milk), and connective tissues.
People with high glandular and connective tissues in the breast and less fatty tissues have high breast density. On the contrary, people with high levels of fat tissues, when compared to glandular and connective tissues, have low breast density.
According to a meta-analysis that looked into more than 42 studies, women with more than 75% breast density had up to 5 times higher risk for developing breast cancer than women with less than 5% breast density.
On mammograms (X-rays to examine human breasts), fatty tissues look dark, and connective and glandular tissues look clear or white. Cancer cells also appear white. As a result, cancer cells may be hidden on mammograms until they have grown or spread in people with higher breast density. This makes breast cancer treatments more complicated.
A study interviewed 262 women in New York and analyzed their mammograms and alcohol intake pattern. According to the study, women who drank at least seven drinks a week had a 12.3% higher breast density than women who don’t drink.
Another 2015 study analyzed the relationship between drinking patterns and breast density in 189 women. This study also reported that women who drank more than seven drinks a week had higher breast density than those who did not drink.
Alcohol Metabolizing Genes & Breast Cancer Risk
The ALDH2 gene helps produce the Aldehyde dehydrogenase (ALDH) enzyme. Changes in the gene can lead to problems in the production of the ALDH enzyme. This enzyme helps in clearing alcohol from the body.
According to studies, people with the AA and GA genotype of the Single Nucleotide Polymorphism (SNP) rs671 of this gene have a higher risk for developing breast cancer when they consume alcohol than people with the GG genotype.
|AA||Increased risk of breast cancer on alcohol consumption|
|GA||Increased risk of breast cancer on alcohol consumption|
|GG||Normal risk of breast cancer on alcohol consumption|
According to a Korean study, women who had the CYP2E1 c2 allele and drank at least once a month had a 1.9-fold increased risk for developing breast cancer than non-drinking women with the CYP2E1 c1/c1 genotype.
The GSR gene (Glutathione-Disulfide Reductase gene) helps produce the GSR enzyme. This enzyme helps in preventing oxidative stress and cell damage in the body.
The SNP rs1002149 in this gene is associated with breast cancer risk on alcohol intake. The T-carriers of this SNP showed a 24% higher risk for developing breast cancer when they consumed more than 10 grams of alcohol a day. The GG carriers did not show such a risk.
|GG||No risk of breast cancer because of alcohol consumption|
|GT||Increased risk of breast cancer on consuming more than 10g alcohol/day|
|TT||Increased risk of breast cancer on consuming more than 10g alcohol/day|
Alcohol & Breast Cancer: Non-Genetic Risk Factors
Number Of Drinks And Drinking Pattern
The risk for breast cancer increases with an increase in alcohol consumption. A meta-analysis of 53 reports reported the following.
- The risk of breast cancer in women increased by 32% when they had 3-4 drinks/day.
- The risk of breast cancer in women increased by 46% when they had more than 4 drinks/day.
The study also suggested that the risk of breast cancer increased by 7% for every additional drink the woman has had per day
It is not enough to calculate the number of drinks to analyze the risk for breast cancer. The drinking patterns should also be taken into account.
Drinking multiple alcoholic beverages in the same sitting is considered riskier than consuming moderate quantities over the week. For instance, a woman who has seven drinks over the weekend and refrains from drinking on weekdays is at higher risk for breast cancer than a woman who has one drink a day.
Studies show that early-life exposure to environmental carcinogens increases a woman’s risk of developing cancer. The age between menarche (the first menstrual cycle) and the first pregnancy is considered a high-risk period.
Women who drink excessively or take up binge drinking at an early age are more affected by alcohol during this period and are at a higher risk of being diagnosed with breast cancer in the future.
Type Of Alcohol Consumed
Different types of alcohol have different levels of ethanol content in them. This can increase or decrease the risk of developing breast cancer. Also, certain alcoholic beverages like red wine have antioxidant properties that can protect against cancers to an extent.
A small study reported that resveratrol, a type of polyphenol (plant-compound) found in red wine, can bring down estrogen production in the body and decrease the risk of developing breast cancer. Red wine also seems to help reduce breast density in young premenopausal women.
Another study talks about the chemoprotective effects of beer. Beer contains the pods of a coneflower called hop that gives the drink its bitterness and flavor. Hops contain substances like xanthohumol and hop-bitter acids that may have cancer-preventing abilities.
Please Be Advised: Alcohol consumption more than your daily dose can increase your risk of accident, injury or hangover.
Recommendations To Reduce Breast Cancer Risk
Limit Alcohol Intake
Some people just cannot completely avoid drinking. Drinking in moderation may help in such cases. Taking one or lesser drink per day can help bring down the risk of breast cancer.
Avoid Binge Drinking
When the body suddenly processes excess alcohol, it struggles and leads to excess production of acetaldehyde and estrogen.
Avoid binge drinking and split your alcohol dosage evenly throughout the week. According to the National Institute on Alcohol Abuse and Alcoholism, binge drinking in women equals consuming more than four drinks in 2 hours.
Avoid Alcohol Use During Adolescence And Early Adulthood
Early exposure to alcohol, especially between the periods of menarche to the first pregnancy, can cause irreparable damage to the breast cells. Several studies have shown that the breast cells are easily damaged/altered by environmental factors in the early periods.
In the United States, the minimum drinking age is 21. However, reports show that 1 in 4 women aged between 12-20 have consumed an alcoholic beverage in the last month.
Women who have started drinking before 25 years seem to be at a higher risk for developing breast cancer than women who started later.
Avoid consuming alcohol before 21 and limit the number of drinks you consume after the legal age.
Undergo Genetic Testing
Breast cancer is a result of several genetic and environmental factors, and alcohol consumption is just one of them. Genetic testing will tell you if you are genetically at a higher risk for developing breast cancer. If so, you may want to control the environmental factors better.
If you belong to the high-risk category, getting a mammogram periodically helps too.
- Alcohol consumption is associated with many health conditions, including breast cancer.
- Ethanol in drinking alcohol increases the production of acetaldehyde (AA) and estrogen in the body. In excessive amounts, these lead to cell damage, abnormal cell division and growth, and the development of cancer.
- Alcohol also increases breast density. Breast density is associated with an increased risk of breast cancer. High breast density also makes it challenging to identify tumors in their early stages.
- Changes in the ALDH2, CYP2E1, and the GSR genes can increase or decrease a person’s risk of developing breast cancer on alcohol consumption.
- The number of drinks had, the drinking pattern, age during alcohol consumption, and the type of drink consumed can all affect a person’s risk for developing breast cancer.
- Choosing the right drink, avoiding binge drinking, limiting alcohol intake, and opting for genetic testing can help bring down breast cancer risk.