Diagnostic imaging may increase the risk of testicular cancer

Early and repeated exposures to diagnostic imaging, such as X-rays and CT scans, may increase the risk of testicular cancer, suggests a new study from researchers at Penn Medicine published online today in PLOS ONE.

“The steady increase in cases of testicular germ cell tumors (TGCT) over the past three or four decades suggests that there is a risk of environmental exposure involved, but no definitive risk factor has ever been identified,” said senior author Katherine L. Nathanson, MD, deputy director of Penn’s Abramson Cancer Center and Pearl Basser Professor of BRCA-Related Research at the Perelman School of Medicine at the University of Pennsylvania. “Our data suggest that the increased use of diagnostic radiation below the waist in men over the same time period may contribute to the increased incidence.”

Kevin Nead, MD, who led the study while in the radiation oncology department at Penn and is now at MD Anderson Cancer Center, is the lead author.

Radiation is a known risk factor for cancer because of its ability to damage DNA. When cells are unable to properly repair damaged DNA, genetic mutations can result.

TGCT is the most common cancer in the United States and Europe in men aged 15 to 45 years. The incidence rate has dropped from about three in 100,000 men in 1975 to six in 100,000 men today. Almost 9,500 cases will be diagnosed by the end of 2020.

Studies on the role that diagnostic radiation, especially CT scans, can play in TGCT have been limited. Previous reports have relied on occupational exposure, including military and nuclear workers, not patients receiving diagnostic radiation in clinical care, and no recent studies have assessed the impact of radiation diagnostics.

In this latest research, the authors conducted an observational study of 1,246 men aged 18 to 55 with and without testicular cancer at Penn Medicine. Participants were asked to complete a questionnaire that obtained information about known and suspected risk factors for testicular cancer and diagnostic imaging during their lifetime, including location on the body and the number of exposures, before their diagnosis. Tumor samples were also taken.

After adjusting for known risks of testicular cancer, including cryptorchidism and family history, race, age, and other factors, the researchers found there was a statistically significant increased risk of cancer. testes among those reporting at least three x-ray exposures, including an x-ray of the colon and a CT scan below the waist, compared to men without such exposure.

People with three or more exposures to diagnostic radiation had a 59 percent increased risk of having CTCT compared to people without exposure to diagnostic radiation. The risk was also high for people exposed to diagnostic radiation in their first decade of life, compared to those first exposed at age 18 or older.

“If our results are validated, efforts to reduce medically unnecessary and preventable testicular exposure should be considered, in part through efforts to reduce the radiation dose and optimize protective practices where appropriate,” the authors wrote. .