Patient Awareness of Alcohol Consumption and Breast Cancer Risk

Introduction

In the United States, breast cancer is a leading cause of malignancy in women, and it is estimated that about 1 in 8 women will develop an invasive breast cancer during their lifetime. ¹ Although most breast cancer efforts focus on treatment, almost 30% of breast cancers are attributable to modifiable risk factors. ²

One key and underrecognized risk factor for breast cancer is alcohol consumption. Alcohol is considered by the International Agency for Research on Cancer to be a class 1 carcinogen and causally related to breast cancer, in addition to 6 other types of cancer (e.g., oral, esophageal, colon, and rectum). ³ In the United States, sixteen percent of breast cancers diagnosed in 2014 were attributable to alcohol consumption, accounting for 39 060 cases. ² Alcohol is the third leading modifiable risk factor for cancer, behind tobacco and excess body weight. ² In 2025, the U.S. Surgeon General released an advisory on alcohol and cancer risk, which included a recommendation to add cancer warning labels on alcohol containers. ⁴ Calls for cancer warning labels on alcoholic beverages have since been made by the American Medical Association, as well as leading oncologists.^5,6

Alcohol consumption is known to increase cancer risk, including breast cancer risk, through several pathways. Evidence suggests that alcohol increases serum concentrations of endogenous estrogen, a known contributor to lifetime risk of breast cancer.^7,8 A recent analysis of population data suggests that younger birth cohorts have a higher incidence of some cancers including estrogen receptor positive breast cancer. ⁹ This could potentially be attributed to increased exposure to carcinogenic factors early in life, such as alcohol use and binge-drinking among younger women. ⁹

In addition to its impacts on estrogen regulation, alcohol is metabolized into acetaldehyde, a carcinogen that can damage DNA and interfere with DNA synthesis and repair. ⁸ Indeed, the metabolism of alcohol into acetaldehyde has been associated with breast carcinogenesis. ¹⁰ Ethanol itself can also induce DNA damage and can disturb DNA methylation by impacting folate absorption. ⁸

The relationship between alcohol and breast cancer is dose-dependent and there is no established safe level of consumption.^11-19 For each 10 g (approximately 0.7 standard drinks) of alcohol consumed daily by adult women, there is a 7-12% increase in risk for breast cancer.^13,16,20,21 Even light-to-moderate alcohol consumption, as low as 3 to 6 standard drinks a week is associated with a significantly increased breast cancer risk. ²⁰ Furthermore, consuming an average of at least 30 g of ethanol (i.e., at least 2 standard drinks) daily is associated with a 51% greater risk of breast cancer compared to individuals who do not consume alcohol. ²⁰

The American Cancer Society (ACS) states that from a cancer prevention perspective, it is best to abstain from alcohol. ²² However, if women choose to drink, they should follow ACS and the 2020-2025 US Dietary Guidelines for Americans and not exceed 1 drink (14 g ethanol) per day.^23,24 It is worth noting, however, that these guidelines are under scrutiny, with several groups, including the US Surgeon General, calling for these guidelines to be revised in light of alcohol’s demonstrated cancer risks.^4,5

Globally, there is a trend toward stricter alcohol use guidelines. In 2016, after reviewing the available evidence, the UK updated their alcohol use guidelines, concluding that, since the last guidelines were published in 1995, the cancer risks of alcohol are now understood to occur with any level of use. ²⁵ Furthermore, in reviewing 5915 systematic reviews on alcohol consumption and health, Canada recently lowered its low-risk consumption guidelines to no more than 2 standard drinks per week. ²⁶

Despite the well-demonstrated association between alcohol intake and breast cancer risk, patient and provider awareness is still lacking. A recent study found that less than 20% of a sample of women attending a breast screening program and less than 50% of health care professionals identified alcohol as a breast cancer risk factor in the United Kingdom. ²⁷ US awareness of alcohol consumption as a risk factor for breast cancer appears to be low (24-38%).^28-32 Additionally, some studies have found lower awareness among Black individuals compared to white individuals.^28,30,31

Low awareness of alcohol as a risk factor for breast cancer is especially concerning given the rates of alcohol use among women. In the United States, over 50% of women of child-bearing age report consuming alcohol in the past month and nearly 28% report engaging in past-month binge-drinking (i.e., having four or more drinks at a time). ³³ Moreover, younger women are now drinking more than they ever have in the past. In older generations, men were over twice (2 times) as likely to drink alcohol than women, but in younger generations women are now drinking as much as men, ³⁴ raising significant clinical and public health concerns.

Improving awareness of the cancer risks associated with alcohol use may be a key strategy in reducing alcohol-related breast cancer incidence. Based on the Transtheoretical Stages of Change model, awareness of how a behavior is problematic or produces negative health consequences is the first step in someone changing their behavior in a health-positive way. ³⁵

This study aimed to analyze awareness of the association between alcohol use and breast cancer risk among female patients presenting to Mayo Clinic’s Family Medicine and Community Internal Medicine continuity clinics. Furthermore, we sought to characterize the associations between awareness of this risk and patient sociodemographic factors, family and medical history, and health behaviors. In doing so we sought to identify which patients are most likely to benefit from education around alcohol and breast cancer risk.

Methods

Results

We recruited 1000 study participants, although not every participant answered every question. The median age was 57 (IQR of 46-63) years. In total, 24.5% (245/999) of participants reported having never been pregnant, 19.0% (189/996) reported having a first-degree relative with a history of breast cancer, 6.9% (69/997) reported smoking 1 or more cigarettes in the past 6 months, 58.9% (589/1000) reported having at least a bachelor’s degree, and 75.6% (753/996) reported participating in annual mammograms. Patient demographics and clinical characteristics are summarized in Table 1.

Patient awareness of factors that influence lifetime risk of breast cancer is presented in Table 2. Most patients (844/990 [85.3%]) identified family history of breast cancer as a factor that increases lifetime risk of breast cancer. Among the 982 patients who completed the question about alcohol consumption as a risk factor for breast cancer, 475 (48.4%) identified that alcohol use increases risk of breast cancer. Among the remaining 507 (51.6%) participants, 341 (34.7%) were not sure if there was an association between alcohol consumption and breast cancer risk, 143 (14.6%) believed there was no association, and 23 (2.3%) believed that alcohol consumption decreases the risk of breast cancer.

Table 3 summarizes patient responses about personal alcohol consumption. One hundred twenty-five (12.6%) participants reported having never consumed alcohol. Among the participants who had consumed alcohol, the median age of initiation of alcohol consumption was 20 years. Additionally, 32.0% (266/832) reported drinking more than twice per week in the past 12 months, and 19.0% (152/801) reported drinking 3 or more drinks on the days that they drank.

The number and percentage of patients who reported that alcohol use increases lifetime risk of breast cancer are shown in Table 4 for each patient characteristic. In single-variable analysis, factors associated with awareness of alcohol consumption as a risk factor for breast cancer included older age at first pregnancy (P = 0.010), more education (P < 0.001), and higher frequency of alcohol consumption in the last 12 months (P < 0.001).

In a multivariable analysis, we included all variables from Table 4 that had a P value less than 0.20 that were asked of all participants. These included patient age, history of pregnancy, highest level of education completed, and frequency of alcohol consumption in the past 12 months. In this analysis, characteristics associated with awareness of alcohol use as a risk factor for breast cancer included patient age (63 y vs 46 y, OR = 1.25; 95% CI, 1.04-1.50; P = 0.019), having never been pregnant (OR = 1.39; 95% CI, 1.00-1.92; P = 0.048), level of education (master’s degree vs some college, OR = 1.90; 95% CI, 1.42-2.54; P < 0.001), and frequency of alcohol consumption in the past 12 months (3 to 4 times per week vs 3 to 11 times per year, OR = 1.34; 95% CI, 1.09-1.65; P = 0.005) (see Table 5). In a separate analysis excluding those who had never been pregnant, we examined the association of age at first birth, adjusting for the aforementioned variables. In this model, age at first birth was not associated with awareness of alcohol as a risk factor for breast cancer (30 y vs 21 y, OR = 1.05; 95% CI, 0.80-1.37; P = 0.73).

Discussion

Overall, awareness of alcohol consumption as a risk factor for breast cancer was found to be low in our sample of 1000 women, with over 50% of participants being unaware of the increased risk of breast cancer associated with alcohol consumption. In total, 871 participants reported having ever used alcohol, and of those who had done so in the last year, 58% consumed alcohol at least weekly, placing them at an increased risk of breast cancer.

Our study is novel for two primary reasons (1) it examined a clinical population of US primary care patients and (2) it examined the association between awareness of alcohol and breast cancer risk with understudied factors such as pregnancy history, tobacco use and mammography screening. While awareness was low in our study, previous studies that have estimated awareness of alcohol’s contribution to breast cancer risk in various populations have found even lower levels of awareness (e.g., 3.3% to 40.6%).^{5,27-32,38-44} One potential explanation may be related to education, which, like in our sample, has been associated with a greater likelihood of identifying alcohol as a risk factor for breast cancer.^{5,29,31,42,44} Education is a fundamental social determinant of health, and education-related factors including health literacy, social and economic resources, or healthcare access may explain this finding. ⁴⁵ According to the Bureau of Labor Statistics, 45% of women aged 25 to 64 years had a bachelor’s degree or higher in 2019. ⁴⁶ In contrast, in our sample, 59% of participants had a bachelor’s degree or higher. Given that our sample was more educated than the general population, our study may have overestimated true awareness of alcohol consumption as a breast cancer risk factor.

The group of participants who are at the highest risk of breast cancer had the highest rate of awareness: about 71% of those who consume alcohol every day were aware of the association between alcohol use and breast cancer. Conversely, young women who drank infrequently, who are at lower risk of breast cancer, were the most unaware of this risk. Some studies have found similar findings in that those with higher-risk alcohol consumption, including binge-drinking, have greater awareness of the association between alcohol and breast cancer.^28,30,31 In addition, those with a personal or family history of breast cancer were also more aware of the impact of alcohol consumption on breast cancer risk than those without. ³¹ People who are at higher risk of breast cancer, such as those who frequently consume alcohol or those with a family breast cancer history, may have more resources on this topic and therefore have heightened awareness.

The fact that people who drank everyday were aware of the alcohol-cancer association suggests that awareness by itself is not enough to motivate full behavior change. Indeed, evidence has demonstrated that increasing awareness of alcohol harms can lead to greater intention to decrease alcohol consumption.^47,48 However, actual reduction in alcohol consumption may only be observed when awareness interventions are paired with interventions that provide practical advice on reducing alcohol use. ⁴⁸ Such practical guidance may not be routinely and effectively provided to patients who consume alcohol daily.

Our data demonstrate a critical gap in knowledge in that a majority of patients are unaware that alcohol consumption, an important modifiable risk factor, increases their risk of breast cancer. Thus, the results emphasize a need for further public and patient-level education. Reasons for low awareness are likely multi-faceted but may include poor knowledge among providers, hesitancy of providers to initiate discussions about alcohol use, time constraints during healthcare encounters, and misleading messages from the alcohol industry.

First, providers may not educate patients because they themselves may be unaware of the link between alcohol and breast cancer. A recent study from the United Kingdom demonstrated that fewer than half of the health professionals who were part of a breast screening program were aware of alcohol’s association with breast cancer. ²⁷ Another explanation for low awareness levels is that providers often fail to screen for and discuss alcohol use with patients, ⁴⁹ and women in particular are less likely to receive brief intervention for their alcohol use. ⁵⁰ Additionally, even when conversations are had with patients, provider advice is often vague and tentative, as opposed to that of tobacco counseling. ⁵¹

Another reason for low public awareness may be the relationship between alcohol corporations and cancer charities. Studies have documented how several alcohol corporations have linked their brand to cancer charity organizations through marketing materials (e.g., pink ribbons on beverage labels) and donations to cancer charities from product sales, which sends a mixed message to consumers. ⁵² Moreover, alcohol industry organizations themselves employ multiple strategies that misrepresent evidence of the link between alcohol and cancer, especially for breast cancer. ⁵³

To prevent breast cancer, it is crucial to first increase public awareness of the association between alcohol and breast cancer. Increased screening for alcohol use during healthcare visits and informing patients of this risk may be one way to increase awareness,^54,55 especially in primary care settings. Lifestyle medicine practitioners with expertise in behavioral science are one important group of health care providers who can utilize counseling and brief intervention to help patients, especially those at higher risk of alcohol use and/or breast cancer, to decrease or eliminate alcohol use as a cancer prevention strategy.^54-56

In addition to intervention at the patient level, public educational efforts may reach those who do not receive routine medical care. Public educational interventions that have demonstrated effectiveness for increasing awareness of the alcohol-cancer link include public awareness campaigns about alcohol and cancer,^57-59 as well as warning labels on alcohol, ⁶⁰ much like the warning labels that exist for tobacco. While less studied, school-based educational interventions on alcohol and cancer risk, may be another avenue to increase awareness, and could start as early as middle or high school. ⁶¹ If successful, one benefit of the subsequent increased awareness of the link between alcohol use and cancer is that it may generate support for alcohol policies that may be key to creating environments that are conducive to reducing alcohol consumption and alcohol-related harms.^62-65

Conclusion

Our results indicate that awareness of alcohol consumption as a risk factor for breast cancer was generally low and decreases in those at lower risk of breast cancer. Future research endeavors should identify reasons for this knowledge disparity. To prevent future breast cancer cases and deaths, it is critical that awareness is increased, which can be done through both patient and public-level interventions that educate individuals about the risks of alcohol and cancer. It is important that such interventions be paired with practical strategies and environmental supports, such as alcohol policies, to reduce alcohol consumption.

Ethical Considerations

This study was deemed exempt by the Mayo Clinic Institutional Review Board (IRB #17-002209).

Consent to Participate

The Mayo Clinic Institutional Review Board (IRB #17-002209) waived the need for informed consent.

ORCID iD

Elizabeth K. Farkouh https://orcid.org/0000-0002-7379-058X