Radiation-related cancer mortality higher for U.S. flight crew

Flight attendants and airline pilots in the U.S. have the highest and second-highest proportion of radiation-related cancer mortality among occupations, suggest findings published August 17 in JAMA Internal Medicine. 

Researchers led by Vishal Patel, MD, from Harvard Medical School and Brigham and Women’s Hospital in Boston found higher odds of death among these occupations from these cancers, including for breast, central nervous system, and prostate cancers, among others. 

“For clinicians, the practical takeaway is that occupational history is one of the most underused fields in the chart,” Patel told AuntMinnie. Knowing that a patient spent a career at altitude is a reason to be attentive: encourage guideline-concordant screening and adherence, keep a low threshold for evaluating symptoms, and counsel on co-exposures that are modifiable, including UV exposure through cockpit windscreens and the sleep and circadian disruption that comes with the schedule.” 

Aircrew members are constantly exposed to cosmic radiation at commercial flight altitudes. Data points to professionals in this occupation receiving the largest average annual dose of ionizing radiation out of any other occupational group in the U.S. 

The Patel team noted that data are unclear about whether exposure among aircrew leads to higher cancer-related mortality. It studied whether pilots and flight attendants have increased risk-adjusted radiation-related cancer mortality compared with other occupations. 

The researchers used data from over 12.7 million death certificates of people across 503 occupations via the National Vital Statistics System. This included 14,190 pilots and 7,170 flight attendants.  

Of the total occupations, flight attendants (6.9%) and pilots (6.7%) had the highest and second-highest risk-adjusted percentage of deaths from radiation-related cancers. Females in both occupations had higher risk-adjusted radiation-related cancer mortality (pilots, 8.1%; flight attendants, 7.8%), but males also had high mortality (pilots, 6.1%; flight attendants, 6.5%). However, the team did not observe this pattern for cancer deaths not tied to radiation. 

Patel said two internal checks point to in-flight cosmic radiation rather than something else about the job.  

“First, aircrew ranked near the median of all occupations for cancers not thought to be radiation-related,” he told AuntMinnie. “Second, aircraft mechanics and assemblers who work around aircraft, jet fuel, and hydraulic fluids but do not accumulate flight hours showed no elevation.” 

Patel also noted that while the Federal Aviation Administration (FAA) formally recognizes aircrew as occupationally exposed to ionizing radiation, U.S. aircrew are not subject to federal dose limits or monitoring requirements. 

Finally, for the breast cancer finding, Patel said breast radiologists should not consider these occupations a formal risk factor that changes imaging decisions. 

“What we would say is that a career at altitude is worth knowing about as context rather than as a formal risk input. It is a reason to reinforce guideline-concordant screening and adherence, which can be genuinely difficult for people whose schedules keep them away from home, and to take symptoms seriously,” he said. “If flight hours or dosimetry data are ever linked to cancer outcomes at scale, that is what would be needed to say something quantitative about individual risk. We're not there yet.” 

Read the full study here.