A friend of mine who has lung cancer has never smoked in her life. Her husband of 20 years however does. So why did she get the disease and he didn’t?
Lung cancer is more prevalent among men than women but prevalence in the fairer sex is catching up. This is a trend that is causing concern among health experts especially as lung cancer rates in men are on the decline. Lung cancer has long overtaken breast cancer as the main cause of cancer mortality in women.
According to the American Cancer Society, projections for 2010 in terms of lung cancer mortality is 86,000 in men and 71,000 in women. In contrast, projection for breast cancer death for this year is 40,000.
So what is the reason behind this gender difference?
Smoking in women is not increasing and therefore cannot be the main cause of increase in lung cancer. However, women seems to be more vulnerable to the effects of cigarette smoke, be it as a first-hand smoker or as a passive smoker. Non-smoking women are three times more likely to have lung cancer than non-smoking men.
According Brenda Edwards, associate director of the surveillance research program at the National Cancer Institute:
That is why researchers are trying to figure out women’s increased vulnerability to lung cancer. One group put forward the hypothesis that the female hormone estrogen may be to blame. Estrogen has also already been linked to genetic mutations that led to the formation of breast tumors. Lung cells have been found to produce estrogen in women as well as in men, but much more in the former than in the latter.
To test this hypothesis, the researchers exposed female mice by placing them in cigarette smoke- filled chambers for 6 hours each day, five days a week for three, eight or 20 weeks. They then compared the genetic make up of those exposed to those who were not exposed.
“Researchers found differences in 10 genes around an enzyme called cytochrome P450 1b1, which is known to break down estrogen and tobacco smoke. The 1b1 enzyme activates cancer-causing agents in tobacco and converts estrogen to a more active form that appears to cause DNA mutations. Estrogen may, in essence, be adding fuel to the fire that occurs when lung cells are exposed to tobacco smoke.”
Aside from the natural levels of estrogen the female body produce, women nowadays also take medications to boost estrogen levels, from contraceptive pills to hormone replacement pills to ease menopausal symptoms. The higher the estrogen levels in the blood, the more susceptible they might be.