Then Do Men. This increased risk in women can be seen by the fact that female smokers tend to develop lung cancer at an earlier point in their smoking careers then men. Women, typically get lung cancer after 37.4 pack years of smoking, versus 56.3 pack years for men. The answer has to do with the interaction between cigarette smoke and the cells of the lung.
Cigarette smoke causes an increased expression of a receptor on the surface of lung cells.
GRP is a mitogen, i.e. a substance that acts as a cellular growth factor. GRP, when bound to its receptor, GRPR, stimulates mitosis or cell division. It turns out that the expression of this receptor is more pronounced in women than it is in men. The reason for this is that GRPR gene is located on the X chromosome. Thus woman have two copies of the gene, and, therefore, a higher probability of it becoming mutated, especially when the lung cells are exposed to the carcinogens found in cigarette smoke.