A new study has revealed an association between smoking and loss of the Y chromosome in blood cells that increases the risk of developing cancer in males.

Smoking is widely recognized as one of the biggest risk factors for cancer. A new study has now demonstrated that smoking is associated with the loss of the Y chromosome in blood cells, potentially explaining why smoking is more of a risk factor for cancer among men.

Only men have the Y chromosome, which "may in part explain why men in general have a shorter life span than women, and why smoking is more dangerous for men," says lead researcher Prof. Jan Dumanski, of Uppsala University in Sweden.


Researchers have already shown that male smokers are more likely to develop cancer outside of the respiratory tract than female smokers. In the new study, the discovery of a potential link between smoking and genetic damage that only affects men could account for this difference.

'We have previously in 2014 demonstrated an association between loss of the Y chromosome in blood and greater risk for cancer. We now tested if there were any lifestyle or clinical factors that could be linked to loss of the Y chromosome," explains Lars Forsberg, another of the researchers.

Most people have 46 chromosomes in their cells, and two of these are sex chromosomes. Females have two X chromosomes, whereas males have one X and one Y. It is believed that the Y chromosome contains around 50-60 genes that provide the body with instructions for creating protein.

Lars Forsberg, researcher at the Department of Immunology, Genetics and Pathology, Uppsala University, and responsible for the study, said that they have now tested if there were any lifestyle- or clinical factors that could be linked to loss of the Y chromosome. Out of a large number of factors that were studied, such as age, blood pressure, diabetes, alcohol intake and smoking, they found that loss of the Y chromosome in a fraction of the blood cells was more common in smokers than in non-smokers'.

"Our results indicate that the Y chromosome has a role in tumor suppression, and they might explain why men get cancer more often than women," said Prof. Dumanski, regarding the previous study published in Nature Genetics.

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.

The researchers said that these results indicate that smoking can cause loss of the Y chromosome and that this process might be reversible and they 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.