Flight attendants may be at an increased risk of breast and other cancers due to work-place exposures including cosmic radiation and circadian rhythm disruption form traveling across multiple time zones. This cancer incidence study will determine whether female flight attendants are at increased risk of breast and other cancers and whether the risk is dose-related. The study will include a cohort of approximately 10,000 women who were employed as flight attendants for one or more years.

Breast cancer cases will be identified from telephone interviews of living subjects and next-of-kin of deceased subjects, as well as from death certificates. The interview will also provide information about non-occupational risk factors for breast cancer such as parity. Both internal and external comparisons will be made. The primary analysis will evaluate the risk associated with occupational exposure within the cohort, controlling for non-occupational risk factors by stratification or modeling. The secondary analysis will compare the incidence of breast cancer in the cohort to that in the general population, with adjustment for factors such as lower parity which might increase breast cancer risk in the cohort independent of occupational exposure to cosmic radiation and circadian rhythm disruption. The risk of other ionizing radiation-related cancers, such as leukemia, lung cancer, and thyroid cancer, among flight attendants will also be evaluated. The results of the study will apply to female flight crew and frequent fliers.