Alcohol and Breast Cancer

By | October 20, 2014

In the early days of Pink’tober a fellow blogger ranted about a restaurant who wanted to advertise on her blog. Her objection was that the restaurant was offering a drink special, and that alcohol was a risk factor for breast cancer – so how dare they advertise a drink discount in association with breast cancer.

This got me worried. Was I going to need to change my drinking habits? Did I have to give up wine? Now, I don’t drink a lot, but I do enjoy a glass of wine or two with dinner three or four times a week.

Eventually, I got around to looking up what the literature had to say about alcohol and breast cancer. The good news is, I don’t need to give up my wine drinking. Actually, a recent study in the Journal of Clinical Oncology goes so far as to say that I should continue (or increase) my alcohol consumption – because it has no effect on my survival associated with breast cancer, but alcohol consumption “is associated with a reduced risk of death from cardiovascular disease” (Newcomb et al, 2013, p.1944).

Now there are studies that do say that alcohol is associated with an increased risk of re-occurance – however, the risk is in a small subset of the population which might have additional co-mobidities that aren’t taken into account. One such study (which has issues such as defining alcohol use as all or nothing, rather than taking about levels of alcohol use – then concluding about moderate use of alcohol), uses nice vague language: “Our results point to a potential positive association between alcohol intake and risk of recurrence and breast cancer death, which appeared to be limited to overweight and obese, but not normal weight, women” ([highlighting added by me] Kwan et al, 2010, p. 4414). This same study had in the conclusion “Consuming three to four alcoholic drinks or more per week after a breast cancer diagnosis may increase risk of breast cancer recurrence, particularly among postmeopausal and overweight/obese women, yet the cardioprotective effects of alcohol on non-breast cancer death were suggested” (Kwan et al, 2010, p.4410). Wow! That conclusion certainly does not follow from the evidence provided in the article. I’m really surprised it got through peer review! It is a good demonstration of why one should read beyond the abstract – as the contents may demonstrate that the conclusions don’t follow from the study!

Now there are other studies (Chen et al, 2011) that do show that alcohol consumption is a risk factor, but the effect size is really low (1-3%).  When you read the study, terms like “but the p value for interaction was not significant” (p.1886) – meaning, you cannot conclude anything from the data as it was not statistically significant – keep popping up in the discussion. So, when you combine the small effect size with the lack of statistical significance, you get a study that doesn’t really say much.

And so, I’m not convinced that having wine with dinner increases ones risk of breast cancer. And I don’t believe that after diagnosis, having wine with dinner increases ones risk of recurrence. So, I shall happily enjoy that glass of wine, cause well, my heart appreciates it 🙂

References

Chen, W. Y., Rosner, B., Hankinson, S. E., Colditz, G. A., & Willett, W. C. (2011). Moderate alcohol consumption during adult life, drinking patterns, and breast cancer risk. Jama, 306(17), 1884-1890. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3292347/

Kwan, M. L., Kushi, L. H., Weltzien, E., Tam, E. K., Castillo, A., Sweeney, C., & Caan, B. J. (2010). Alcohol Consumption and Breast Cancer Recurrence and Survival Among Women With Early-Stage Breast Cancer: The Life After Cancer Epidemiology Study. Journal of Clinical Oncology, 28(29), 4410-4416. doi:10.1200/JCO.2010.29.2730

Newcomb, P. A., Kampman, E., Trentham-Dietz, A., Egan, K. M., Titus, L. J., Baron, J. A., . . . Willett, W. C. (2013). Alcohol consumption before and after breast cancer diagnosis: associations with survival from breast cancer, cardiovascular disease, and other causes. J Clin Oncol, 31(16), 1939-1946. doi:10.1200/JCO.2012.46.5765

 

2 thoughts on “Alcohol and Breast Cancer

  1. Maha Bali
    I guess studies that find no significant difference R useful, thojgh, in the sense that they say: we tried to find a correlation but we did NOT find it, and that’s news. That there is no correlation in this study. Of course, it could have been a poorly designed study, or smsll numbers, or whatever, but it has that value.
    Reply
  2. Becky Post author

    I agree that it is useful to have studies that show no significance – they just need to conclude no significance. I have trouble when the study concludes as if the results were significant, when they were not.

    Reply

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