The research we are talking about today was conducted in the USA and analyzed the data of over 88 thousand adults followed for approximately 14-20 years as part of the large US PLCO (Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial), documenting 1,679 new cases of colorectal cancer.
Participants provided detailed information on their alcohol consumption at four different stages of life, starting from age 18, allowing researchers to build a complete picture of habits over time.
The results clearly show that those who drink 14 or more drinks a week, the equivalent of two glasses of wine a day, have a 25% higher risk of colorectal cancer than those who drink less. But the most alarming data concerns those who have maintained high consumption throughout their adult life: in this case the risk jumps up to +91%, almost double, with a particularly marked impact on rectal cancer.
It’s not just a question of quantity
The study did not limit itself to measuring how much people drink today, but reconstructed the alcohol habits of participants in four different age groups, from youth to adulthood. This approach made it possible to understand that it is the duration and consistency of consumption over time that makes the difference, rather than individual episodes.
The researchers classified participants as current drinkers, former drinkers, or teetotallers, and further divided them based on their average lifetime drinking: less than one drink per week, one to fewer than seven, seven to fewer than fourteen, and fourteen or more.
An important clarification: the threshold for “heavy” consumption is not the same for everyone. Following American dietary guidelines, the researchers applied criteria differentiated by sex: for women, consumption is considered heavy above 14 drinks per week, while for men the threshold rises to over 21 drinks per week. This means that, for the same consumption, the risk for women occurs earlier.
However, an encouraging fact emerges for those who decide to quit. Former drinkers, even with a history of moderate or heavy drinking, show a risk of colorectal cancer similar to that of those who have always drunk little.
Furthermore, those who have stopped drinking have a lower risk of developing non-advanced adenomas, i.e. those intestinal polyps that represent the precursors of cancer and which, if not treated, can develop into cancer. Quitting, in other words, brings real and measurable benefits.
What it means in practice
Two glasses of wine a day is a threshold that many consider harmless. Yet, according to these data, it is enough to shift the oncological risk in a statistically significant way. It’s worth remembering that a “standard drink” corresponds to approximately 150 ml of wine, a measurement that is often less than what you actually pour into a glass.
Already known risk factors for colorectal cancer include a diet rich in processed meats and low in fibre, obesity and a sedentary lifestyle. However, alcohol has been adding to this picture for some time now with increasingly solid evidence.
The authors of the research underline that the results do not change existing recommendations: to reduce the risk of cancer, the advice remains to minimize alcohol consumption, ideally eliminating it completely. However, this study adds a new perspective: even those who have been drinking for years can benefit from the decision to stop.
As researcher Erikka Loftfield of the National Cancer Institute stated, the data suggests that the oncological risk of former drinkers, even with a history of high consumption, tends to realign with that of those who have always drank little.
