The relation with cancer risk and survival
According to the several medical publications, chronic consumption of alcohol is a well-known cause of several cancers. These include cancers of the mouth, throat (pharynx), voice box (larynx), esophagus, liver, colon and rectum, breast and pancreas. Especially when alcohol is consumed chronically together with smoking, it significantly increases the risk of getting a cancer .
More important than the type of alcoholic beverage, it is the amount of alcohol that matters. The active ingredient found in alcohol is ethanol. When consumed chronically, ethanol can lead to tissue inflammation or destruction. This inflammation can be the first step in the emergence of cancers (especially liver and esophagus). Ethanol can also influence the oestrogen level in the body and this might increase the risk of oestrogen sensitive cancers, such as ER-positive (oestrogen receptor positive) breast cancer .
According to a recent review in the American Journal of Public Health, the majority of alcohol-attributable female cancer deaths were from breast cancer (56% to 66%), whereas upper airway and esophageal cancer deaths were more common among men (53% to 71%) .
Although there is a relation between alcohol consumption and the risk of developing certain cancers, the relation between alcohol consumption and cancer survival is less clear . For instance, several studies on breast cancer have shown that moderate drinkers experienced a better cardiovascular status and an improved overall survival compared with non-drinkers, which might be confusing compared to previous research studies . Other studies reported no link between moderate alcohol intake and breast cancer recurrence and that moderate post-diagnosis alcohol consumption is unlikely to have a major adverse effect on the survival of women with breast cancer [6,7].
One study reported that folic acid intake might reduce the risk for breast cancer caused by alcohol consumption, although more research is needed to reveal the role of folic acid and alcohol discontinuation . Taking into account the known effects of alcohol on the health, it is however recommended to discontinue or lower alcohol intake.
Interaction with treatment
Alcohol can interact with some chemotherapy treatments in the same way other drugs can interact with each other. Always talk to your physician before drinking alcohol during a cancer treatment.
There are some chemotherapy drugs that have a known interaction with alcohol and it is important not to consume alcohol when taking these drugs. This is the case for instance with procarbazine and lomustine. Procarbazine is a drug often used to treat Hodgkin lymphomas in children and young adults, some types of non-Hodgkin lymphomas, and some types of brain tumors. Lomustine, also called CCNU, is a chemotherapy drug that is used to treat various tumors, such as, but not limited to, breast cancer, cervical cancer, testicular cancer, myeloma, ovarian cancers, kidney cancer, stomach cancer, melanoma skin cancer and brain tumors. [9,10]
Alcohol and appetite
Some chemotherapy drugs can make you feel sick or might reduce your appetite. Having a small alcoholic consumption might increase your appetite again and help you relax. But here again: always first check with your physician before doing so. Keep in mind that alcoholic drinks can bring a total different experience due to changes in taste because of the chemotherapy. Furthermore, a sore mouth might give you an uncomfortable feeling when drinking alcohol.
Based on the numerous studies on alcohol and chemotherapy, the general recommendation by the American Cancer Society for alcohol consumption during treatment is not to drink alcohol unless your doctor is OK with it. After cancer treatment, the general recommendations are one glass or less per day for women and two glasses or less per day for men. [11,12]
-  Enger et al.; Alcohol consumption and breast cancer oestrogen and progesterone receptor status; Br J Cancer. 1999 Mar; 79(7-8): 1308–1314.
-  David E. Nelson et al. Alcohol-Attributable Cancer Deaths and Years of Potential Life Lost in the United States. Am J Public Health. 2013 April; 103(4): 641–648.
-  Scoccianti et al. Female breast cancer and alcohol consumption: a review of the literature. American journal of preventive medicine. 2014;46(3 Suppl 1):S16–25.
- Simonsson et al.; Pre- and postoperative alcohol consumption in breast cancer patients: impact on early events. SpringerPlus 2014, 3:261
- Kwan et al.; Postdiagnosis alcohol consumption and breast cancer prognosis in the after breast cancer pooling project.
- Cancer Epidemiol Biomarkers Prev. 2013 Jan;22(1):32-41
- Am et al.; Alcohol consumption and survival after a breast cancer diagnosis: a literature-based meta-analysis and collaborative analysis of data for 29,239 cases. Cancer Epidemiol Biomarkers Prev. 2014 Jun;23(6):934-45
- Islam et al. Alcohol and dietary folate intake and the risk of breast cancer: a case-control study in Japan. Eur J Cancer Prev. 2013;22(4):358–66. Epub 2012/11/28. http://dx.doi.org/10.1097/CEJ.0b013e32835b6a60. [PubMed]
- Armand et al. ; Reappraisal of the use of procarbazine in the treatment of lymphomas and brain tumors . Ther Clin Risk Manag. 2007 Jun; 3(2): 213–224.
-  http://www.cancer.org/cancer/cancercauses/dietandphysicalactivity/alcohol-use-and-cancer