When it comes to smoking and cancer, men are mysteriously worse off: over 30% of cancer deaths in males are connected to smoking, compared to ~20% in women. It’s not all due to lung cancer either – male smokers also have a higher incidence of non-lung cancers compared to female smokers. Why the difference?.
A recent study provides evidence that the answer is related to the relatively small chunk of DNA that confers maleness in humans: the Y sex chromosome. The researchers found a strong positive association between smoking and the loss of the chromosome Y in circulating blood cells. Losing the chromosome Y in blood cells is actually more common than might be expected. In fact, the same researchers previously discovered that loss of the chromosome Y occurs more frequently as men age over 70 (even in the absence of smoking). Loss of the chromosome Y is correlated with shorter life expectancy and higher risk of cancers. Thus, while this study does not establish a causal link between smoking, Y chromosome loss, and cancer, it does provide a tantalizing potential explanation for why male smokers are at greater risk for developing cancers than their addicted female counterparts.
The study also shows that the rate of Y chromosome loss decreases in men who quit smoking, indicating that this increased risk could be reversible! While this hypothesis needs to be tested further, these results further strengthen the notion that it’s never too late to kick the habit.
Edited by Shay Neufeld. Many thanks to Dr. Mitch McVey, an Associate Professor of Molecular Biology at Tufts University, for his expert opinion and insight.
References and further reading:
NBC coverage of the study: ‘Y Quit? Smoking Destroys Male Chromosome‘
Original research paper: ‘Smoking is associated with mosaic loss of chromosome Y‘
Previous study showing that loss of chromosome Y increases with age: ‘Mosaic loss of chromosome Y in peripheral blood is associated with shorter survival and higher risk of cancer‘
2014 study showing % of smoking-related cancers: ‘What proportion of cancer deaths in the contemporary United States is attributable to cigarette smoking?