Men Who Smoke Are More Likely to Lose Y Chromosome, Have Higher Mortality Rates

Smoking can cause loss of the Y chromosomes in men, putting them at a higher risk of developing cancer than women, according to a recent study.

Researchers at Sweden's Uppsala University found that men who smoke are two to four times more likely than non-smoking men to lose their Y chromosomes, HealthDay reported.

The scientists have demonstrated an association between smoking and loss of the Y chromosome in blood cells. The researchers have previously shown that loss of the Y chromosome is linked to cancer. Since only men have the Y chromosome, smoking is a greater risk factor for cancer among men, Reuters reported.

"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," Jan Dumanski, an Uppsala professor who worked on the study, told Reuters. "This ... may in part explain why men in general have a shorter life span than women and why smoking is more dangerous for men."

Epidemiological data show that male smokers have a greater risk of developing cancer outside the respiratory tract than female smokers.

Researchers found that the association between smoking and loss of the Y chromosome was dose dependent, i.e. loss of the Y chromosome was more common in heavy smokers compared to moderate smokers. In addition, the association was only valid for men who were current smokers. Men who had been smoking previously, but quit, showed the same frequency of cells with loss of the Y chromosome, as men who had never smoked.

"These results indicate that smoking can cause loss of the Y chromosome and that this process might be reversible," Forsberg added. "We found that the frequency of cells with loss of the Y chromosome was not different among ex-smokers compared to men who had never smoked. This discovery could be very persuasive for motivating smokers to quit."

How the loss of the Y chromosome in blood cells, induced by smoking, is connected with the development of cancer throughout the body is still not clear. One possibility is that immune cells in blood, that have lost their Y chromosome, have a reduced capacity to fight cancer cells.

The findings are detailed in the journal Science.