Alcohol and Breast Cancer
Breast cancer is an important health concern among women as they age. Developing breast cancer can have a profound effect on women psychologically, physically and socially. It is also important from a national perspective: Canada has the second highest incidence of breast cancer in the world (trailing only the United States). It is estimated that in 2003 there will be over 21,000 new cases of breast cancer among women in Canada (Canadian Cancer Society).
The provinces with the highest rates of new cases of breast cancer are Manitoba (116/ 100,000), Nova Scotia, (112), Quebec (110), Alberta (109), and PEI (107). (Canadian Cancer Society)
What is the Risk of Breast Cancer for Women in Canada?
According to Canadian Cancer Agency figures: Women have a lifetime probability of 11.4 % of developing breast cancer (or 1 in 8.8 women will develop it). While women tend to think of it as a middle age disease, the probability of developing breast cancer is higher among women aged 60-69 and 70-79 than in younger women. See below for factors associated with breast cancer in women.
Does Drinking Affect the Risk of Developing Breast Cancer in Pre and Postmenopasal Women?
Yes, absolutely. There is association between the level of alcohol consumption and increased risk of breast cancer. Particularly, there is a significantly increased risk of breast cancer where the woman drinks more than two drinks daily over a period of years. (Stoll)
Women who drink moderately (<2 drinks a day) and who are on estrogen replacement therapy for five years are at greater risk a breast cancer. They have about double the risk of developing breast cancer of women who are only on the hormone replacement therapy or women who only drink alcohol (Chen et al.)
For many years it was thought that it might be the smoking not drinking that was tied to breast cancer risk (and many drinkers are also smokers) However, more recent research says no. It is clearly the alcohol.
At What Level of Drinking, Does the Risk of Breast Cancer Increase?
A large study found that compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 for an intake of 35--44 g per day alcohol (in other words, drinking between 3 and 3.5 standard drinks a day), and 1.46 for those drinking more than 45 g per day alcohol. In other words, compared to women who are non drinkers, the relative risk is 32% for between 3 and 3.5 standard drinks a day, and 46% higher for more than slightly less than 4 standard drinks a day.
The relative risk of breast cancer increased by 7.1% for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in smokers and women who had never smoked. (Collaborative Group)
How Does Alcohol Affect the Risk of Breast Cancer?
We are still learning about the exact mechanism. It has been suggested that alcohol inactivates a tumour suppressor (BRCA1) (Fan et al). Or alcohol consumption may elevate blood levels of estrogen for women (Sarkar et al; Singletary & Gapstur) and that increased estrogen leads to higher risk because breast cancer development is related to hormones.
Some of the breast cancer risk may be due to other dietary factors tied to drinking alcohol (such as low folate intake). (Singletary & Gapstur) Low B-vitamin intake associated with higher drinking may increase risk of breast cancer by decreasing women’s bodies capacity to repair deoxyribonucleic acid (DNA). (Sellers et al)
About 4% of the breast cancers in women are directly attributable to alcohol. The more women who drink at higher levels, the greater the number of breast cancer cases we are likely to see. So conservatively, over 840 women in Canada each year might be able to prevent developing breast cancer by reducing their alcohol consumption to safer levels for women.
Are There Ways to Reduce the Potential Harms?
An obvious one is to encourage women to reduce their level of drinking to lower risk levels [one drink a day if possible, or abstaining completely if that is their goal and would most likely to lead to other improvement in their lives].
There is some evidence that dietary folate (but not other B vitamins) may have a protective effect of preventing breast cancer in older post menopausal women who drink alcohol (Boughton, 2001). Many older women drinkers are not getting adequate folate.
If women decide to continue to drink, they should also be trying to make sure they have adequate folate in their diet. It is fairly easy to get more folic acid: for example regularly eating fortified cereals for breakfast (even most cereals are good sources of folic acid); beans and lentils; also spinach, broccoli, peas, orange juice, or peanuts.
Understanding the Implications of Breast Cancer for Older Women Who Drink
Very little if anything has been written on the implications of breast cancer for older women who drink.
Older women can benefit from counselling, education, and emotional support both before and after any breast cancer testing, no matter what the result. Finding out that they have breast cancer may lead some women who have been abstaining or who have reduced their level of drinking to relapse, however this will likely depend on the other coping strategies they have developed and the level of support they have from others. Older women need to have good information about the nature of the disease and their prognosis. Developing breast cancer does not have to be a life sentence.
There is a strong need for advocacy to make sure older women who develop breast cancers or other cancers, whether or not they drink, receive appropriate treatment:
Older women account for 44 percent of all newly diagnosed cases of breast cancer, and 93 percent of them are diagnosed before the disease has metastasized. However, women in their 70s and 80s are much less likely to undergo surgery or receiving breast-conserving surgery than younger women.
According to an American study in the mid 1990s, older women were treated less aggressively the older they became, and this trend was not attributable to the increased presence of other medical problems associated with advancing age. It showed that older women were less likely to undergo surgery, more likely to receive breast-conserving surgery as opposed to mastectomy, and less likely to receive radiotherapy following breast-conserving surgery. Whether or not the women had other diseases (co-morbidity) was less important than their age in how they were treated. (Newschaffer)
A more recent British study found that older patients received fewer diagnostic and staging procedures and less treatment with advancing age and that survival rates specific to the types of cancer declined with age. However the study pointed out this was because they had fewer biopsies to confirm the tumor, and with a given type of tumor, they received less care and survived a shorter time. The researchers also found that many clinical cancer trials have had arbitrary upper age limits. (Turner)
Ageism may account for the common attitude that asks: why intervene if an woman with cancer does not have long to live anyway? However, the fact is that a 75-year-old woman in Canada still has a life expectancy of about 11 years. This should not be overlooked by patients, families or the healthcare staff.
Does Drinking Alcohol Affect Breast Cancer Survival?
One study pointed out that women drinking alcohol at heavier levels tend to be diagnosed with their breast cancer later, a point where it had begun to spread (it was less likely to be localized) (Vaeth & Satariano). We are not sure why. It may be that heavy alcohol consumption will be linked to other unhealthy behaviours. In addition, women who drink more frequently may have less awareness of or less access to cancer screening services. Heavy exposure to alcohol may also contribute to accelerated tumor growth once breast cancer is present. (Vaeth & Satariano)
Surprisingly, another study suggests that women who when they were diagnosed were regularly consuming 3.5 – 8 drinks of alcohol a week experienced a longer relapse free survival (16% higher) than non drinkers. (Arab et al) The relapse-free survival advantage rose to 66 % for women who were consuming more than 8 drinks a week. We have to be very careful here, because it may be that the women who were the sickest or had the more advanced cancer were less likely to drink.
Factors Associated with Increased Risk of Breast Cancer
According to the American Cancer Society, the following factors are associated with risk of breast cancer.
- Family history of breast cancer:
- Personal history of breast cancer: A woman with cancer in one breast has a 3- to 4-fold increased risk of developing a new cancer in the other breast or in another part of the same breast.
- Race: White women are slightly more likely to develop breast cancer than are African-American women.
- Previous breast biopsy
- Previous breast irradiation
- Early Life Menstrual periods (before age 12)
- Not having children or first child after 30.
- Several years use of Hormone replacement therapy
- Alcohol: Compared with nondrinkers, women who consume 1 alcoholic drink a day have a very small increase in risk, and those who have 2 to 5 drinks daily have about 1˝ times the risk of women who drink no alcohol. Alcohol is also known to increase the risk of developing cancers of the mouth, throat, and esophagus.
- Obesity and high-fat diets especially after menopause.
Factors Associated with Decreased Risk of Breast Cancer:
Two factors associated with slightly reduced risk of breast cancer are : breast feeding and early life physical activity.
American Cancer Societywww.cancer.org/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_factors_for_breast_cancer_5.asp
Arab, L.; Simonsen, N.; Strain, S.; London, S.; Dressler, L.; Schilling, J. Alcohol intake and breast cancer survival. American Journal of Epidemiology, 153(11):s106, 2001.
Boughton, B. Dietary folate protects against breast cancer in women who drink alcohol. Lancet Oncology, 2(9):528, 2001.
Fan, S.; Meng, Q.; Gao, B. Alcohol stimulates estrogen receptor signaling in human breast cancer cell lines. Alcohol Research, 6(1):30, 2001.
Canadian Cancer Statistics, 2003www.bc.cancer.ca/vgn/images/portal/cit_776/61/38/56158640niw_stats_en.pdf
Chen, W.; Coldtz, G.A.; Rosmer, B.; Hankinson, S.; Hunter, D.; Manson, J. ; Stamptfer, M.; Willett, W.; & Speizer, F. Use of Postmenopausal Hormones, Alcohol, and Risk for Invasive Breast Cancer . Annals of Internal Medicine, 19 November 2002 Volume 137 Number 10 , 798-804
Collaborative Group on Hormonal Factors in Breast Cancer Alcohol, tobacco and breast cancer: Collaborative reanalysis of individual data from 53 epidemiological studies, including 58515 women with breast cancer and 95067 women without the disease. British Journal of Cancer, 87(11):1234-1245, 2002.www.bjcancer.com
Newschaffer, C.J.; Penberthy, L.; Desch, C. E. et al. "The effect of age and comorbidity in the treatment of elderly women with nonmetastatic breast cancer," January 8, 1996 Archives of Internal Medicine 156, pp. 85-90.
Sarkar, D.K.; Liehr, J.G.; Singletary, K.W. Role of estrogen in alcohol promotion of breast cancer and prolactionomas. Alcoholism: Clinical and Experimental Research, 25(5):230s-236s, 2001.
Sellers, T. A.; Kushi, L.H.; Cerhan, J.R.; Vierkant, R.A.; Gapstur, S.M.; Vachon, C.M.; Olson, J.E.; Therneau, T.M.; Folsom, A.R. Dietary folate intake, alcohol, and risk of breast cancer in a prospective study of postmenopausal women. Epidemiology, 12(4):420-428, 2001.
Singletary, K.W.; Gapstur, S.M. Alcohol and breast cancer: Review of epidemiologic and experimental evidence and potential mechanisms. Journal of the American Medical Association (JAMA):2143-2151, 2001
Smith-Warner, S.A.; Spiegelman, D.; Yaun, S.S.; et al. Alcohol and breast cancer in women: A pooled analysis of cohort studies. Journal of the American Medical Association JAMA 279(7):535-540, 1998.
Stoll, B.A. Alcohol intake and late-stage promotion of breast cancer. European Journal of Cancer, 35(12):1653-1658, 1999.
Turner NJ,; Haward RA,; Mulley GP,; Selby PJ: Cancer in old age—is it adequately investigated and treated? British Medical Journal, 319: 309-312, 1999.
Vaeth, P.A.C.; Satariano, W.A. Alcohol consumption and breast cancer stage at diagnosis. Alcoholism: Clinical and Experimental Research, 22(4):928-934, 1998
Page last updated Sunday October 31, 2004
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