Evidence has shown that alcohol can cause cancer. There is no safe level of alcohol consumption. Reducing your alcohol consumption to no more than two standard drinks a day can lower your risk.
What is cancer?
Cancer is a disease of the body’s cells. The body is constantly making new cells to replace worn-out ones, to grow, or to heal itself after an injury. Normally cells grow and reproduce themselves in an orderly way. Sometimes, cells can reproduce themselves in an uncontrolled way, which can lead to cancer. 
In many cases we don’t know why this happens, but we do know that a number of lifestyle risk factors, such as, smoking, drinking alcohol, UV radiation, being physically inactive or inheriting a faulty gene, can cause cells to change. These abnormal cells may grow into a lump that is called a tumour. 
Tumours can be benign (not a cancer) or malignant (a cancer). Benign tumours do not spread to other parts of the body. A malignant tumour is made up of cancer cells. These cells can spread beyond the area where the cancer first developed. If untreated the cancer cells may invade and destroy surrounding tissues. 
There are more than 200 different kinds of cancer, each with its own name and treatment. 
Alcohol is classified as a Group 1 carcinogen. This is the highest carcinogen rating, equal to tobacco smoke and asbestos. [3,4]
What cancers can alcohol cause?
Alcohol-related cancer can develop in many different parts of the body.  Research has found convincing evidence of alcohol causing a range of cancers in humans such as: [2,4]
Head and neck cancers: oral cavity, pharynx, larynx, oesophagus
Alcohol damages or destroys cells, and the replacement cells may include cancerous cells. Alcohol starts to be digested in the mouth, and can break down to form acetaldehyde. Acetaldehyde is a cell poison and can have damaging effects on the lining cells of the mouth, throat and oesphagus. [5-7]
High alcohol consumption is a risk factor for stomach cancer.  The stomach is the first organ to have long contact with alcohol. The content of the alcohol stimulates gastric juice secretion within the stomach.  Gastric juices are used to break down food so it can move into the small intestine so its nutrients can be absorbed.  There is evidence that alcohol causes inflammation within the stomach, and it appears this may precipitate the development of cancer. 
Alcohol consumption is associated with an increased risk for developing liver cancer. It is commonly seen in people with alcohol cirrhosis. The development of liver cancer requires long periods of drinking and drinking volumes greater than 10g/day (1 standard drink). 
Click here to learn more on alcohol and liver.
Bowel (colon, colorectal)
Bowel cancer is any cancer within the large intestine or rectum.  Bowel cancer is the second most common cancer amongst males and females in Australia.  Drinking alcohol can increase the risk of developing colorectal polyps. Polyps can start as benign which may become cancerous over time.
When alcohol is digested acetaldehyde is produced, and this can become concentrated in the mucus layer of the bowel. Bowel cancer starts in the mucus layer, and if undetected can spread into the bowel walls. [9,10]
There is an increased risk of breast cancer with alcohol use. Evidence has shown there are different mechanisms by which alcohol can cause breast cancer including hormonal influences, and the level of acetaldehyde circulating throughout the body. 
The facts and figures
Compared to national rates of 7.4%, 11.5% of residents in the ACT have a medium to high alcohol risk for developing cancer. 
There is no evidence that any level of drinking provides any protection against developing cancer. If you choose to drink, to remain at low risk of alcohol-caused cancer, health experts recommend having no more than two standard drinks on any day.