It's bad we don't access to the full study, because we could learn more about the methodology.

Did the study adjust for socio-economic factors? The average income of pilots is much higher then average income of flight attendants, income affects lifestyle which affect cancer rates and access to healthcare.

When comparing occupations, how do the rates of cancer of pilots/flight attendants compare to miners, especially underground miners? Miners got quite lot of radiation exposure from radon in certain regions. How about workers in chemical plants?