Men who smoke are more likely to lose their Y chromosomes than men who don't smoke. This chromosomal loss may be why men are at a higher risk for developing and dying of cancer than are women.
Male smokers are 2.4 to 4.3 times more likely to be missing the Y chromosome in their blood cells than are men who do not smoke or who smoked and quit. The amount of smoking made a difference: Men who smoked more were more likely to lose their Y chromosome. Quitting also made a difference: Some men who quit smoking regained their Y chromosome. The only other factor that was associated with loss of a Y chromosome was age.
This finding comes from research done at the Uppsala University in Sweden. Researchers there collected data from three on-going long-term studies being conducted in that country. These studies--which are being done to examine the effects of lifestyle and behavior on health-- collected blood samples from more than 6,000 men.
Losing a Y chromosome has been linked with having a shorter lifespan as well as an increased risk of developing cancer. However, no one knows for certain if the loss of the chromosome actually causes disease. One theory is that the blood cells that have lost their Y chromosome may not function normally as part of the immune system. These cells may be unable to stop cancers from taking hold and growing.
The Y chromosome, which only men have, is important for sex determination and sperm production. Men have one Y chromosome and an X chromosome, while women have two X chromosomes. A Y chromosome is much smaller than all the other chromosomes.
Smoking causes lung cancer, which is often fatal, and is a major avoidable risk factor in many other diseases, including heart disease, stroke, and emphysema. Male smokers have a higher risk of developing non-lung forms of cancer than women who smoke.
The Uppsala research was published in the journal Science.
