There was once an article on WeChat Moments titled "US Officially Confirms Red Wine Fights Cancer," which claimed that a Yale University study showed "drinking red wine can increase the survival rate of non-Hodgkin's lymphoma patients." Although this article was later identified as misinformation, it had already received "100,000+" views. What I want to tell you here is: how such a rumor came about.
Small-scale Survey
Cannot confirm results and has low persuasiveness
Yale University did conduct a study on the relationship between red wine and the survival rate of non-Hodgkin's lymphoma patients. The results of this study were first reported at the 2009 American Society of Cancer conference and then formally published in the Journal of Cancer Survival in 2010. Although the numbers mentioned in that WeChat article were slightly different from those in the paper, there was no substantial difference, and it can be confirmed that it was quoting that paper.
This study was an epidemiological survey. In scientific research, epidemiological surveys often only discover phenomena and provide hypotheses, and in most cases, they cannot "confirm conclusions." That is to say, just because it was an epidemiological survey, the WeChat article's use of "confirmed" was already an exaggeration.
The study followed the survival status of 575 "non-Hodgkin's lymphoma patients" for a long period. The results showed that the 5-year survival rate for wine drinkers was 75%, while for non-wine drinkers it was 69%. Because these people differed in other aspects besides whether they drank wine, and those factors might also lead to the difference in survival rates. The researchers used statistical tools to eliminate the influence of factors such as age, education, and smoking, and the 5-year survival rate for drinkers was still higher than for non-drinkers. However, it should be noted that these are only the factors that the researchers collected data on, and they cannot cover all influencing factors.
More importantly: in a small-scale epidemiological survey of a few hundred people, the difference between 75% and 69% is actually quite small (although it is considered a "statistically significant difference" in statistics). The researchers also mentioned when discussing the results of the study that wine drinkers might have better socioeconomic conditions. However, data on socioeconomic conditions was not collected. They tried to explain the difference in 5-year survival rates by the dietary habits associated with socioeconomic conditions, but the result was that the difference in "healthy eating" between the two groups (with good and bad economic conditions) was not significant.
In fact, the difference in socioeconomic conditions is more reflected in the medical security conditions. Medical security has a far greater impact on the lifespan of cancer patients than other factors.
In short, this is a very small-scale epidemiological survey with very weak evidence, and its results cannot at all prove that "drinking red wine can increase the survival rate of non-Hodgkin's lymphoma patients."
Large-scale Survey
Drinking alcohol may increase the risk of cancer
If we are really going to discuss the effect of alcohol on cancer, we should look at more studies done by the scientific community. In 2004, Italian scholars summarized research papers from the past 30 years on alcohol and 14 other diseases and injuries, including tumors. The studies involved as many as 156 research projects, with a total of over 110,000 people. They found that as long as you drink alcohol, it increases the risk of developing cancer. The magnitude of the increased risk is related to the amount of alcohol, and it's the same for liquor, wine, or beer—as long as there is alcohol, the risk is increased. For example, drinking 50 grams of alcohol per day (roughly equivalent to 2 liang of 50-degree liquor) increases the risk of oral and throat cancer by 2.1 times, the risk of esophageal cancer, laryngeal cancer, and primary hypertension by about one time, the risk of breast cancer by 55%, the risk of cirrhosis by 6.1 times, the risk of chronic pancreatitis by 78%, the risk of hemorrhagic stroke by 82%, and the risk of liver cancer by 40%.
Although these are also mainly epidemiological surveys that only found "correlation" and hypotheses, not "confirmation," the overall sample size and the magnitude of the increased risk in these studies are far greater than in the Yale study. That is to say, compared to the Yale study, the evidence in these papers that "drinking alcohol increases the risk of cancer" is much stronger.