Plausible biological mechanisms underlying sex differences in radiation-induced lung cancer risk.

Some epidemiological studies suggest that women are at greater risk for radiation-induced lung cancer than men, but this observation is not consistent across all studies. A scientific committee formed by the National Council on Radiation Protection and Measurement evaluated evidence for a sex difference in lung cancer risk from radiation exposures by reviewing animal studies and assessing the biological plausibility that such a difference might exist. The committee identified four mechanisms that could potentially result in greater radiogenic lung cancer risks for women. The first of these is that radiation exposure increases the relative risk for a molecular subtype of spontaneous lung cancer that occurs predominantly in women. The second is that sex chromosome or gene expression differences between men and women place women at greater risk. The third is that hormonal differences between men and women, particularly for oestrogen levels, put women at greater risk. The fourth mechanism is that sex differences in immune system function underlie a sex difference in radiation-associated lung cancer risk. None of these mechanisms has yet been proven to play a role in radiogenic lung cancer risk.