alcohol and breast cancer

A recent small, one-center study highlights a huge issue in breast cancer prevention: our major focus on genetics and genetic testing over the role of modifiable risk factors (in this case: alcohol) in prevention (see breast cancer alcohol bmj2019 in dropbox, or doi.org/10.1136/bmjopen-2018-027371).

Details:

-- 205 women were surveyed on their understanding of the role of alcohol in breast cancer, their ability to assess their own amount of alcohol consumed, and their perspective on the importance of prevention interventions

    -- 102 women from the UK’s National Health Service (NHS) Breast Screening Program (NHSBSP)

    -- 103 women from the “symptomatic breast clinic” (SBC)

        -- NHSBSP patients were older (49% were 51-60 yo, vs 22% in SBC), 60% married, 56% working, 80% “good” general health, more SBC had been treated for breast cancer (35%, vs 3% in NHSBSP), 26% obese/30% overweight, 10% current smokers/33% former

--33 NHS staff were also interviewed

Results:

--alcohol identified as a risk factor for breast cancer (“women” refers to clinic attenders):

    --40/205 women (19.5%)

        --NHSBSP patients: 15.7% 

        --SBC patients: 23.3%

    --16/33 staff (48.5%)

--66.5% of women drank alcohol

--ability to correctly estimate  the alcohol content of any of 4 commonly consumed alcohol drinks, among those who were current drinkers:

    --57.9% felt that they knew how to estimate the alcohol content of drinks, and of these:

        --standard glass of wine: 72% were correct

        --pint of beer: 55% were correct

        --liter of cider: 24% were correct

        --bottle of spirits: 24% were correct

--personal alcohol consumption: more drinkers than nondrinkers were aware of alcohol as a risk factor (25.2% of drinkers vs 10.9% of nondrinkers)

     --so, the authors note that "increased awareness about alcohol is associated with the knowledge necessary (if not sufficient) to facilitate behavior change" [though still seems that 3/4 of them did not know it was a risk factor!!!]

     --and, of those who did not correctly estimate alcohol content of any of the drinks, 86.2% did not identify alcohol as a risk factor!!

-- women agreed that including a brief alcohol prevention focused intervention would not reduce their likelihood of attending the breast clinics or getting mammograms: 30.5% felt that a 5-minute cancer prevention information session would make it more likely they would attend the breast clinics and 69.5% felt it would not matter [no one said that it would make them less likely to attend]

--perception of other potentially modifiable risk factors

    --obesity: 30.4% of NHSBSP and 32.0% of SBC (though, those women who were obese were significantly less likely to consider obesity as a risk factor…)

    --smoking: 48% of NHSBSP and 45.6% of SBC

    --lifestyle: 7.8% of NHSBSP and 5.8% of SBC

    --hormonal meds: 12.7% of NHSBSP and 14.1% of SBC

--Health professionals sample:

    --73% were able to name at least one breast cancer risk factor

    --58% identified obesity as a risk factor

    --52% identified alcohol as a risk factor

    --45% felt they know how much alcohol was in a drink: but in fact only 21-61% were correct for each one of the above 4 drinks

    --15% thought the educational session would attract more patients, 67% though it would not matter, and 1 person thought it would be a deterrent

       --however, some were concerned that the session might increase the "worried well" or come across as "blaming the victim"

Commentary:

--Potentially modifiable risk factors (esp obesity and alcohol) account for 23% of breast cancers

    --alcohol is estimated to be responsible for 5-11% of breast cancer cases, is a risk factor for all age groups, and its relationship with breast cancer is dose-dependent (leading several agencies to recommend zero alcohol consumption)

    --NHS reports that >20% of women 45-64yo drink >14 units of alcohol/week

--in the UK: >54K new cases of breast cancer annually (the most common cancer); >11K women die from breast cancer annually

--one (inappropriately) nagging popular (and popularized) issue is the misconception that moderate alcohol consumption is associated with decreased cardiovascular outcomes

    --see http://gmodestmedblogs.blogspot.com/2015/02/moderate-alcohol-and-cardioprotection.html , which argues that former drinkers are often considered to be in the  “nondrinker” category, but they may have stopped drinking because of high medical/psych comorbidities that themselves put the people at increased mortality risk

    -- http://gmodestmedblogs.blogspot.com/2018/10/alcohol-as-leading-risk-facor-for-death.html , finding that alcohol is the leading risk factor for death in those 15-49 yo, from the perspective of the global burden of disease

    -- http://gmodestmedblogs.blogspot.com/2019/05/stroke-risk-lowest-if-zero-alcohol.html , finding that stroke risk was lowest in those with zero alcohol intake, from a mendelian randomization study

--limitations of the above study: the biggest one is probably that this was a small, single center study, so ??generalizability of results within the UK as well as to other countries

--one comment by the women in focus groups was that those with a family history of breast cancer were less inclined to make lifestyle changes, esp if the relative with breast cancer had a healthy lifestyle.  this brings up to me one of the major issues here: there is so much information and advertising about the genetic basis of breast cancer, that:

    --it is striking how little understanding there is about the modifiable risk factors, even among health professionals, though these risk factors account for a fair % of breast cancer, as above

    --typically there is an interplay between genetics and the environment, and genetics are not themselves determinant [genetics may play a bigger role in BRCA1 and BRCA2 than for some other genetic markers; though even with the BRCA carriers, 30% do not develop breast cancer ever when followed up to age 80 and about 60+% do not develop ovarian cancer: see Kuchenbaecker KB. JAMA 2017; 317(23):2402]. 

    --see http://gmodestmedblogs.blogspot.com/2017/04/23andme-genetic-analysis-approved-for.html on FDA approval of direct-to-consumer 23andMe genetic analysis, which as a test has quite low sensitivity, specificity and positive predictive values, but conceptually reinforces to people that genetics are determinant.

     --http://gmodestmedblogs.blogspot.com/2018/01/dietary-effect-strong-when-high-genetic.html found that dietary changes were actually more effective in those with a high genetic predisposition to weight gain

bottom line: alcohol has been shown to be a modifiable risk factor for breast cancer in >100 studies.  the current study, though done in only one center in the UK with a pretty small number of women, suggests:

--most women were unaware of the breast cancer risks of alcohol, and that there is no clear safe lower limit

--those who drink were largely unaware of the amount of alcohol they consume

--health professionals working in these breast clinics were not well-informed either

--several women in the focus groups felt that genes were determinant, with lack of understanding that there is usually an interplay between environment and genetics. And, if they consider genes to be determinant, no need to change unhealthy lifestyles…

--all of the women in the study were open to educational sessions on modifiable risk factors, though I expect these should be done more by motivational interviewing than simply lecturing on the associations (which might lead to a sense of attacking their chosen lifestyle and maybe a "blaming the victim" feeling instead of allying with the women to help them figure out what can be changed and then helping motivate them)

geoff​

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