A new study shows that even years after quitting, former smokers are still at greater risk of developing head and neck tumors (cancers of the mouth, throat and larynx) than people who have never smoked. And that risk is even higher among those with a history of alcohol abuse.
The idea for the study, published in the journal Cancer Epidemiology and signed by Brazilian researchers, emerged when it was observed that, even with the decrease in smokers in Brazil, cases of cancer continue to appear in people who have given up cigarettes.
“In recent years, we have seen an interesting phenomenon in the clinic. Patients come and say ‘how do I get cancer if I stopped smoking?’. So we hypothesized that quitting smoking has a positive effect, but the question is whether this is maintained in the long term”, says Luiz Kowalski, leader of the head and neck tumor reference center at AC Camargo and professor of head and neck surgery at the USP School of Medicine.
Kowalski, one of the authors of the study, has already participated in other research on the subject. One of them was performed in the 1990s with approximately one thousand patients. In it, it was observed that quitting smoking for a period longer than ten years made the risks of ex-smokers having cancer similar to those of those who had never smoked.
Therefore, it was to be expected that, with the decrease in the number of smokers in the country in recent years, there would also be a reduction in these cancers in this population of ex-smokers, but that was not exactly what happened.
“Some explanations emerged, such as the idea that some tumors were not associated with tobacco, and it began to be discovered that some cancers were associated with HPV. This explained, in part, why the incidence did not fall”, explains Kowalski.
Even with these explanations, the question of why the rate of head and neck cancer did not decrease remained. Then came the initiative to carry out the study in which the impact that smoking had in the long term was investigated.
The survey included more than 200 participants who had been smokers and developed one of the three types of head and neck cancer. Another 318 made up the control group, that is, those who smoked but were not diagnosed with a tumor.
“It has been seen that, for head and neck cancer, if the individual smoked a pack of cigarettes a day for 20 years, he has 3 to 20 times more risk of getting cancer than someone who has never smoked”, says the professor.
This level of risk decreases over time, but still remains. “Even after ten years there is still a higher-than-expected residual cancer risk,” he adds.
According to the study’s estimates, the risk only begins to decrease on average 11 years after quitting the habit, causing a warning that it’s not just quitting smoking, but also taking other measures.
One of them is moderation in alcohol consumption. “If there is a habit of consuming alcoholic beverages and smoking cigarettes, the risk of developing head or neck cancer can be up to a hundred times greater”, says Kowalski.
The specialist explains that alcohol itself does not induce cancer, but it makes it easier for tobacco carcinogens to penetrate the mucosa, increasing the chances of a tumor arising.
On the other hand, the study found that some healthy eating habits — such as consumption of citrus fruits and foods rich in vitamin A — help to reduce the negative impact of smoking.
They, however, cannot delay the harmful effects of cigarettes. “Tobacco overcomes all the positive effects of good nutrition”, says the professor.
Typically seen in men, these head and neck cancers begin to experience a shift in prevalence in recent years. According to Kowalski, while in the 1980s there were an average of eight men with a tumor for a woman, now it’s around two to three men for a woman.
The explanation for this phenomenon still needs to be better studied, but an assumption can be explained with the increase in alcohol and cigarette consumption by women.
Another point that needs to be better investigated is whether the presence of HPV -which is already associated as a risk factor for some cancers- in combination with tobacco would increase the chances of developing one of these tumors.
Even with these points that can be explained in future research, the specialist reiterates the greatest contribution of the work: “It is possible that, when we stop smoking, it is much more a matter of increasing the time until we get the cancer. smoking, but the risk of cancer does not disappear completely”.
