Air crew radiation exposure depends strongly on cruising altitude and Latitude, for example flight Tokyo JP – New York NY is about 67 microsievert.
https://www2.ans.org/pubs/magazines/nn/docs/2000-1-3.pdf
For general comparison astronauts are exposed to approximately 72 millisieverts (mSv) while on six-month-duration missions to the International Space Station (ISS).
https://en.wikipedia.org/wiki/Effects_of_ionizing_radiation_...
According to linear no-threshold model (LNT model) the incidence of cancers due to ionizing radiation can be modeled as increasing linearly with effective dose at a rate of 5.5% per sievert, so a flight crew member receiving 200 mSv lifetime dose should have 1.1 % higher lifetime chance of cancer then general population. LNT is quite good model for high doses, but there is much less confidence for LNT at low doses, there both studies which confirm LNT at low doses and reject LNT at low doses.
For the overall US population risk of developing any cancer is 39.9% for men, 39.0 % for women.
https://www.cancer.org/cancer/risk-prevention/understanding-...
> In terms of absolute risk, about 6.9% of flight attendant deaths were from these cancers — roughly 1 in 14. Among pilots, it was 6.7%. For the general working population, it was 5%, said the study’s first author, Dr. Vishal Patel of Harvard Medical School.
So it looks like LNT is maybe a bit too optimistic at low doses, because (with the caveat I'm not entirely sure what precisely these percentages mean) the reported excesses are 1.9 and 1.7 percentage points.
Without access to the study and study data we don't know what was measured and how it was calculated, because the value for absolute risk in general working population, the value 5%, is very different from other cancer death studies.
According the The American Cancer Society the risk of dying from any cancer is 17.2% for males, 16% for females for the overall US population.
https://www.cancer.org/cancer/risk-prevention/understanding-...