We all know by now that smoking kills. But among smokers, why is it that more men develop and die from cancer than women?
Researchers at Sweden’s Uppsala University appear to have found the answer: male smokers are three times more likely to lose their Y chromosomes than their non-smoking counterparts, Reuters reports.
In a study in the journal Science, the scientists said Y chromosomes more often disappear from blood cells of smokers than those of men who have never smoked or have kicked the habit.
(The Y chromosome is one of the two chromosomes that determine the sex of humans, the other being the X chromosome. Each individual has one pair of sex chromosomes in each cell. The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes.)
Since only men have Y chromosomes, the finding offers a possible answer to why smoking is a greater risk factor for cancer among men than women, according to the report.
“There is a correlation between a common and avoidable risk factor, that is smoking, and the most common human mutation — loss of the Y chromosome,” one of the researchers, Prof. Jan Dumanski, was quoted as saying.
“This may in part explain why men in general have a shorter life span than women and why smoking is more dangerous for men.”
It’s not clear how losing Y chromosomes in blood cells makes a man more prone to cancer, but one possibility is that immune cells in blood that have lost their Y chromosome have a reduced capacity to fight cancer cells, Reuters says.
The team, who analyzed data on more than 6,000 men, also found that men who smoked more lost more Y chromosomes — and that some men who went on to quit smoking appeared to regain their Y chromosomes.
This suggests that the loss of Y chromosomes due to smoking might be reversible.
“This discovery could be very persuasive for motivating smokers to quit,” Lars Forsberg, one of the researchers, said.
Aside from causing lung cancer, smoking is also the world’s leading preventable cause of premature death from chronic conditions such as heart disease, strokes and high blood pressure.
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