We compared the brain cancer risk of male United States Air Force (USAF) aircrew (37 cases) with nonflying Air Force personnel (193 cases) between 1970 and 1989.
Methods: Incident brain cancer cases for both aviators and nonflying USAF personnel were obtained from USAF hospitalization records. Age, race, and calendar time matched controls were randomly selected for each case from the remaining USAF cohort. We estimated brain cancer risks using conditional logistic regression models.
Results: Initially, we observed a statistically significant brain cancer excess for USAF aircrew compared to nonflying USAF personnel (Odds Ratio [OR] = 1.77, 95% Confidence interval [95% CI] 1.17-2.68). However, following adjustment for senior military rank, a socioeconomic status indicator, the USAF aircrew brain cancer risk was markedly reduced (OR = 1.22, 95% CI 0.76-1.95), demonstrating that much of the previously observed USAF aircrew brain cancer risk was attributable to factors other than flying.
Conclusion: The results of this investigation indicate that flying is not an important brain cancer risk factor, at least for USAF aircrew. The positive relationships observed in other studies between commercial aircrew and brain cancer risk may have been confounded by social class differentials.