Researchers followed more than 5,000 crew and found that their risk of breast cancer increased more than 50 per cent, while risks of stomach cancers are raised by as much as 74 per cent.
The study cannot prove what causes this increase, but the authors said increased exposure to ionising radiation from time spent in the thinner upper atmosphere as well as disrupted sleep and meal cycles could be factors.
Published on Tuesday in the journal Environmental Health, the study found a higher rate of every cancer outcome it looked at when age was standardised.
“We report a higher lifetime prevalence of breast, melanoma and non-melanoma skin cancers among flight crew relative to the general population,” said Dr Irina Mordukhovich of the Harvard TH Chan School of Public Health.
“This is striking given the low rates of overweight and smoking in this occupational group.”
The increased cancer risk was seen in breast (3.4 per cent of flight crew compared to 2.3 per cent in the general population), cervical (1.0 per cent compared to 0.70 per cent), gastrointestinal (0.47 per cent compared to 0.27 per cent ), and thyroid (0.67 per cent compared to 0.56 per cent).
They also found that risk of non-melanoma skin cancers rose with every five years spent in the job.
Flight attendants are exposed to multiple known and probable carcinogens in the cabin environment. These include altitude-based radiation, disruption to the body clock through irregular and anti-social shift patterns and poor air quality inside the cabin.
Previous studies have shown cabin crew have some of the highest radiation exposure of any job, including those in the nuclear industry, but this exposure is not required to be routinely monitored as in other sectors.
Many flight attendants were also exposed to high levels of secondhand tobacco smoke before inflight smoking bans were implemented.
Job tenure did not appear to be associated with breast cancer, thyroid cancer or melanoma in all women, but it was associated with higher risk of breast cancer in women who never had children and women who had three or more children, researchers said.
Any current or former US flight attendant was eligible to participate in the study, with the vast majority (91 per cent) currently employed in a cabin crew role.
The study of 5,366 attendants working on domestic and international flights in the US did not examine the health impact of frequent flying among airline passengers.
Authors said the findings suggested additional efforts should be made to minimise the risk of cancer among flight attendants, including monitoring radiation dose and organising schedules.
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