Smoking has killed countless people over the years and it has been projected that between the years 2000 and 2050 about 450 million more people will die from smoking related diseases. In many smokers, lung cancer is the primary cause of death followed by heart disease, however people who smoke can get cancers anywhere in the body including the lips, stomach, pancreas, liver, colon and rectum. Interestingly, there is data to show the men are around two times more likely to suffer from these other forms of cancer then women (excluding sex specific cancers). Up until recently, no one had an explanation as to why this may be. However, a report published in Science suggests that damage to, and loss of the males Y chromosome could account for this difference.
Every person has 46 chromosomes (23 pairs) in the cells of their body that contain and organize all the DNA of your cells. Of these 46 chromosomes, 2 of them are important in determining your sex, called the X chromosome and the Y chromosome. Females have 2 X chromosomes within their cells that help determine what makes you female. Males on the other hand, have one X chromosome and one Y chromosome and it is this Y chromosome that helps make you male. The Y chromosome contains a specific gene, often called the maleness gene, known as SRY. SRY is important in the development of the testes and other genes on the Y chromosome are important in male fertility. Damage to the Y chromosome in the sperm of a male is often associated with infertility. So what does this have to do with smoking and cancer?
The research showed that in over 6000 men, those who smoked had a greater loss of their Y chromosome in their blood cells and the chance of finding a man with loss of their Y chromosome increased as the duration of smoking increased. When the researchers say loss of the Y chromosome they mean it’s gone, obliterated, destroyed by the toxic cigarette smoke. Cancer arises when the DNA in your cells is damaged in such a way to allow the cells to grow uncontrollably (brief intro to cancer). Normally, this damage is to a few genes in your DNA or certain parts of genes. Losing a whole chromosome is a severe form of DNA damage. The researchers think that the loss of the Y chromosome may do two things. 1) It may be a sign that DNA damage has occurred in other parts of the DNA and not just in the Y chromosome and 2) the Y chromosome may be important in keeping a watch for developing cancers and alerting the body so it can be destroyed. Both effects may explain why males are more likely to develop these forms of cancer.
While the researchers only saw the loss of the Y chromosome in the blood cells of smokers, there is other research that shows loss of the Y chromosome is actually a common feature of other cancers. Adding to the intrigue is the fact that other researchers have identified genes on the Y chromosome that are important in suppressing tumour formation (these genes are also found on the X chromosome in women). Future studies will need to see if this result can be seen in other cells of the body. The loss of the Y chromosome may also explain why many men who smoke become impotent. This research shows that cancer may not be the only worry of men who smoke, they may also lose what they cherish most, their manliness.