Radiation from CT Scans Linked to Increased Risk of Cancer

The increased radiation emitted by computed tomographic (CT) scans may increase the risk of cancer in adults and young adults, according to a study recently published in JNCI Cancer Spectrum.


“Worldwide use of computed tomographic (CT) scans has increased. However, the ionizing radiation from CT scans may increase the risk of cancer. This study examined the association between medical radiation from CT scans and the risk of thyroid cancer, lymphoma, and non-Hodgkin lymphoma (NHL) in adults,” the researchers wrote in their abstract.


In this study, researchers conducted a nested case-control study in a cohort constructed from a population-based universal health insurance dataset in Taiwan in 2000-2013. They analyzed 22,853 thyroid cancer cases, 13,040 leukemia cases, and 20,157 NHL cases with their matched controls were included. The average follow-up was approximately 10 years for the three case-control groups, and medical radiation from CT scans were identified through physician order codes in medical insurance data from the index date to three years before a cancer diagnosis. The researchers used conditional logistic regression modeling was used for the overall and subsets of the population defined by sex and age groups to estimate the odds ratio (OR) and 95% confidence interval (CI) of the cancer risk associated with medical radiation.


Following analysis, the results of the study showed that exposure to medical radiation from CT scans was linked with an increased risk of thyroid cancer [OR= 2.55, 95% CI, 2.36 to 2.75] and leukemia (OR=1.55, 95% CI, 1.42 to 1.68). The elevated risk in thyroid cancer and leukemia in association with medical CT was stronger in females than males. They observed no significant association between the risk of cancer and CT scans was observed in overall patients with NHL (OR=1.05, 95% CI: 0.98 to 1.12), however, increased risks were found in patients 45 years of age and. The study found a clear dose-response relationship in patients 45 years of age and young for all three cancers.




“Our study found that CT scans are associated with an increased risk of thyroid cancer and leukemia in adults in all ages and with non-Hodgkin lymphoma in young adults,” said Yu-Hsuan Joni Shao, one of the paper’s authors in a press release. “The risk is stronger in patients who have higher cumulative doses from multiple scans. The increased numbers of people undergoing CT scans have become a public health issue.”