In Japan, scientists studied 63,232 patients and their alcohol use. They screened the patients for other health risks before the study. The study found that patients that drinking 6 ounces of wine, 17 ounces of beer, or 2 ounces of whiskey a day for 10 years can increase risk for cancer by 5 percent. After 40 years of these drinking habits, cancer risk is increased by 54 percent. However, the authors of the study point out that Japanese have a genetic variation which causes them to metabolize alcohol slower, so it may have more of an impact on them.
According to the Centers for Disease Control and Prevention, alcohol has this effect on humans because when we drink alcohol, it breaks down into acetaldehyde. Acetaldehyde is known to damage DNA and prevent the damage from being repaired. When the DNA is damaged, it may cause cells to enter a growth cycle which can lead to tumors.
https://www.cdc.gov/cancer/alcohol/index.htm
nytimes.com/2019/12/09/well/live/alcohol-drinking-cancer.html
