Cancer and smoking: beware, men!
The increased risk of cancer in male smokers was explained by the Y-chromosome
Smoking leads to the destruction of the Y chromosome (only men have it) in blood cells, Swedish scientists have found out. Its loss weakens the body's immunity against cancer cells. This fact explains why smokers suffer from various forms of cancer (except lung cancer) one and a half to two times more often than smokers. The results of the study are presented in the journal Science (Dumanski et al., Smoking is associated with mosaic loss of chromosome Y), and it is briefly reported by New Scientist (Y men are more likely to get cancer than women).
Scientists examined six thousand Swedish men and found that smokers are three times more likely to lose their Y chromosomes than non-smokers. Since this chromosome is the smallest in the human genome and is of no fundamental importance for the survival of cells, it is usually assumed that its loss does not harm the body. However, in recent years, more and more facts have cast doubt on this point of view.
At the beginning of 2014, the same team of scientists presented in the journal Nature Genetics the results of a survey of 1,150 elderly men: it turned out that the disappearance of the Y chromosome from blood cells increases the risk of premature death and shortens life expectancy by an average of five and a half years, as well as four times increases the risk of cancer (Forsberg et al., Mosaic loss of chromosome Y in peripheral blood is associated with shorter survival and higher risk of cancer).
Most likely, scientists say, the reason is that the genes of the Y chromosome are involved in the suppression of malignant tumors: its loss helps cancer cells to escape from the immune system.
It also turned out that the effect of substances contained in tobacco on chromosomes depends on the dose: the more cigarettes men smoke, the more blood cells are deprived of Y chromosomes. However, this process is reversible – for those who quit smoking, the level of full-fledged blood cells returns to normal.
Portal "Eternal youth" http://vechnayamolodost.ru05.12.2014