Photo by Rhoda Baer
Radiologists who graduated from medical school after 1940 do not have an increased risk of dying from radiation-related causes such as cancers, according to a study published in Radiology.
However, the study suggested that male radiologists who graduated before 1940 had a higher risk of death from certain cancers, including acute myeloid leukemia and non-Hodgkin lymphoma.
Researchers said these findings point to the success of efforts to reduce occupational radiation doses over the past several decades.
The team noted that female radiologists did not have an increased risk of all-cause mortality or cancer-related mortality, regardless of when they graduated from medical school.
However, the small number of women in this study prevented the researchers from studying the subjects’ mortality rates in detail. And very few female radiologists worked during the early period of the study, when radiation exposures were likely highest.
To conduct this study, the researchers analyzed records from the American Medical Association Physician Masterfile, a database established in 1906 that has grown to include current and historical data for more than 1.4 million physicians, residents, and medical students in the US.
The team compared cancer incidence and mortality rates between 43,763 radiologists and 64,990 psychiatrists who graduated from medical school between 1916 and 2006. Psychiatrists were chosen as a comparison group because they are unlikely to have had occupational radiation exposure.
“Our most important finding is that radiologists have lower death rates from all causes of death combined, compared to psychiatrists, and had similar risks of cancer deaths overall,” said study author Martha Linet, MD, of the National Cancer Institute in Bethesda, Maryland.
Results in males
The researchers found that, among male subjects who graduated after 1940, the risk of all-cause mortality was lower for the radiologists than the psychiatrists (relative risk [RR]=0.94; 95% CI: 0.90, 0.97), and the risk of death from cancer was similar (RR=1.00; 95% CI: 0.93, 1.07).
In contrast, male radiologists who graduated before 1940 had higher mortality rates from certain cancers.
They had a higher risk of skin cancer mortality (RR=6.38; 95% CI: 1.75, 23.20) that was driven by an excess of melanoma (RR=8.75; 95% CI: 1.89, 40.53).
They had an increased risk of death from all myeloid leukemias (RR=1.43; 95% CI: 1.00, 2.05) that was driven by acute myeloid leukemia and/or myelodysplastic syndromes (RR=4.68; 95% CI: 0.91, 24.18).
And they had an increased risk of death from lymphomas (RR=2.24; 95% CI: 1.31, 3.86) that was driven by non-Hodgkin lymphoma (RR=2.69; 95% CI: 1.33, 5.45).
The researchers also found an increased risk of cerebrovascular deaths in the male radiologists who graduated before 1940 (RR=1.49; 95% CI: 1.11, 2.01).
The team said the reduced health risks for more recent radiology graduates are likely due to developments and improvements in radiation protection and monitoring, along with improvements in equipment safety.
“Most of the findings of increased risk were in the earlier radiologists,” Dr Linet noted. “We do feel there is evidence that decreases in dose in the United States and other countries seem to have paid off, reducing risks in recent graduates.”
Results in females
The researchers said there were no clear increases in mortality in the female radiologists compared with the female psychiatrists.
The risk of all-cause mortality was lower in the radiologists, as was the risk of death from circulatory diseases, but the risk of cancer-related mortality was similar between the radiologists and the psychiatrists.
However, the researchers said the relatively small number of female deaths in this study prevented detailed investigation. Only 2% of female radiologists (208/8851) and 3% of female psychiatrists (524/17,493) died, compared to 12% of male radiologists (4260/43,763) and 16% of male psychiatrists (7815/47,443).
