Airline cabin crew are occupationally exposed to cosmic radiation and jet lag with potential disruption of circadian rhythms. This study assesses the influence of work-related factors in cancer incidence of cabin crew members. A cohort of 8,507 female and 1,559 male airline cabin attendants from Finland, Iceland, Norway and Sweden was followed for cancer incidence for a mean follow-up time of 23.6 years through the national cancer registries. Standardized incidence ratios (SIRs) were defined as ratios of observed and expected numbers of cases. A case-control study nested in the cohort (excluding Norway) was conducted to assess the relation between the estimated cumulative cosmic radiation dose and cumulative number of flights crossing six time zones (indicator of circadian disruption) and cancer risk. Analysis of breast cancer was adjusted for parity and age at first live birth. Among female cabin crew, a significantly increased incidence was observed for breast cancer [SIR 1.50, 95% confidence interval (95% CI) 1.32-1.69], leukemia (1.89, 95% CI 1.03-3.17) and skin melanoma (1.85, 95% CI 1.41-2.38). Among men, significant excesses in skin melanoma (3.00, 95% CI 1.78-4.74), nonmelanoma skin cancer (2.47, 95% CI 1.18-4.53), Kaposi sarcoma (86.0, 95% CI 41.2-158) and alcohol-related cancers (combined SIR 3.12, 95% CI 1.95-4.72) were found. This large study with complete follow-up and comprehensive cancer incidence data shows an increased incidence of several cancers, but according to the case-control analysis, excesses appear not to be related to the cosmic radiation or circadian disruptions from crossing multiple time zones.Airline cabin crew are occupationally exposed to ionizing radiation with doses 2-6 mSv per year. 1 This is roughly twice the average annual dose from natural and medical sources received by the general population. Cosmic radiation in the common cruising altitudes (8,000-10,000 m) consists mainly of gamma and neutron radiation, with some heavy nuclei. In 1990, the International Commission on Radiological Protection recommended that in-flight radiation exposure to jet aircrew should be regarded as occupational exposure. 2 Of the radiation-related cancers, only breast cancer has shown increased incidence rates among airline personnel consistently in several studies. Out of the seven cohort studies of cabin crew, 3-9 all but one 6 indicate an increased incidence of breast cancer. However, the excess risks seem to be higher than can be explained by the low radiation doses received, 10 and several other factors may contribute to the observed excess.Cabin crew also work in shifts including work at night and are exposed to jet lags (a temporary condition after air travel across several time zones) dependent on time, distance and direction (east-west vs. north-south) of flight routes. Such exposures may contribute to circadian disruption, including suppression of the chronobiotic neurohormone melatonin, which has anticancer properties. [11][12][13] There is accumulated epidemiologic and biologic eviden...

Background: Earlier studies have found increased breast cancer risk among female cabin crew. This has been suggested to reflect lifestyle factors (for example, age at first birth), other confounding factors (for example, age at menarche), or occupational factors such as exposure to cosmic radiation and circadian rhythm alterations due to repeated jet lag. Aims: To assess the contribution of occupational versus lifestyle and other factors to breast cancer risk among cabin attendants in Finland. Methods: A standardised self-administered questionnaire on demographic, occupational, and lifestyle factors was given to 1041 cabin attendants. A total of 27 breast cancer cases and 517 non-cases completed the questionnaire. Breast cancer diagnoses were confirmed through the Finnish Cancer Registry. Exposure to cosmic radiation was estimated based on self-reported flight history and timetables. A conditional logistic regression model was used for analysis. Results: In the univariate analysis, family history of breast cancer (OR = 2.67, 95% CI: 1.00 to 7.08) was the strongest determinant of breast cancer. Of occupational exposures, sleep rhythm disruptions (OR = 1.72, 95% CI: 0.70 to 4.27) were positively related and disruption of menstrual cycles (OR = 0.71, 95% CI: 0.26 to 1.96) negatively related to breast cancer. However, both associations were statistically non-significant. Cumulative radiation dose (OR = 0.99, 95% CI: 0.83 to 1.19) showed no effect on breast cancer. Conclusions: Results suggest that breast cancer risk among Finnish cabin attendants is related to well established risk factors of breast cancer, such as family history of breast cancer. There was no clear evidence that the three occupational factors studied affected breast cancer risk among Finnish flight attendants. E arlier studies of cancer incidence and cancer mortality among aircrew personnel have shown that overall cancer risk incidence and mortality are comparable with that in the general population.1 However, several studies have found increased breast cancer risk among female cabin crew. [2][3][4][5][6][7][8][9] This has been suggested to reflect occupational exposure to cosmic radiation, hormonal alterations due to repeated jet lag, lifestyle factors, or confounding by factors such as age at menarche and menopause. The contribution of various factors has remained unclear, due to the fact that all earlier reports have limited extent of information on potential confounders-that is, the well known risk factors for breast cancer.We conducted a nested case-control study of breast cancer among cabin attendants in Finland. The purpose of the study was to assess the contribution of occupational versus nonoccupational factors to breast cancer risk among cabin crew. METHODS Data collectionThe source population consisted of all Finnish female airline cabin attendants, who were born in 1960 or before. A total of 1098 eligible woman were identified in the source population from the files of Finnair and Finnish Cabin Crew Union (table 1).In the source populat...

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