PEM PEARL: Projected Lifetime Cancer Risks From Current Computed Tomography Imaging
TLDR: Data analysis from 143 US hospitals in 20 states by UCSF looking at CT scans in patients of all ages from 2018-2020 compared against National Cancer Institute data. They were able to model projected risk of cancer in children and adults from CT scans and other data. Overall, from their model CT scans could be responsible for 5% of all cancers diagnosed each year. Children under 1 year were at most risk.
The Details
Published in JAMA on April 14th, 2025 and it has been all over the news. Patient level data was obtained from 143 US hospitals looking at patients who had any CT scans. Age, sex, body diameter, scanner type, type of exam, radiation dose, scan length, and other technical acquisition data were obtained for a 2 year period from January 2018 to December 2020. Estimations of absorbed doses of radiation were stratified per organ. The Projected lifetime risk of cancer was estimated based on the National Cancer Institute’s risk assessment tool which uses risk models from the National academy of Sciences Biologic Effects of ionizing Radiation for specific cancers and data from recent follow up of Japanese atomic bomb survivors. The data from the CT scans performed was then applied against the models of projected cancer rates, and future cancer estimates were based on a linear model of the total radiation dose received. Uncertainty estimates and Sensitivity analysis were conducted to account for variability in populations.
Based on 93 million CT scans performed in the US in 2023 on 61,510,000 patients, they estimated the total cancer risk, from the data obtained from prior years, and estimated that a resultant 102,700 patients would develop cancer from CT scan radiation. The cancer projection risks were highest in children under 1 year old, with estimations of 20 per 1000 examinations. The next highest risk group was in Adults age 50-59. Abdominal and Pelvis CT scans contributed the largest risk in Adults and Head CT contributed to the largest cancer risk in children. This data suggests a much higher risk of cancer than previously thought.
The Bottom Line
We have to do CT’s, there is no way around it, as it can be lifesaving. But we need to recognize the risks and do our best to mitigate them. This data did show that Children receive far less CT scans than adults overall, which we should be proud of. But this study is a reminder that when imaging, we still need to think twice, be judicious, use alternate imaging modalities when available, and use your evidence based guidelines to try and mitigate possible harm.
The Details
Published in JAMA on April 14th, 2025 and it has been all over the news. Patient level data was obtained from 143 US hospitals looking at patients who had any CT scans. Age, sex, body diameter, scanner type, type of exam, radiation dose, scan length, and other technical acquisition data were obtained for a 2 year period from January 2018 to December 2020. Estimations of absorbed doses of radiation were stratified per organ. The Projected lifetime risk of cancer was estimated based on the National Cancer Institute’s risk assessment tool which uses risk models from the National academy of Sciences Biologic Effects of ionizing Radiation for specific cancers and data from recent follow up of Japanese atomic bomb survivors. The data from the CT scans performed was then applied against the models of projected cancer rates, and future cancer estimates were based on a linear model of the total radiation dose received. Uncertainty estimates and Sensitivity analysis were conducted to account for variability in populations.
Based on 93 million CT scans performed in the US in 2023 on 61,510,000 patients, they estimated the total cancer risk, from the data obtained from prior years, and estimated that a resultant 102,700 patients would develop cancer from CT scan radiation. The cancer projection risks were highest in children under 1 year old, with estimations of 20 per 1000 examinations. The next highest risk group was in Adults age 50-59. Abdominal and Pelvis CT scans contributed the largest risk in Adults and Head CT contributed to the largest cancer risk in children. This data suggests a much higher risk of cancer than previously thought.
The Bottom Line
We have to do CT’s, there is no way around it, as it can be lifesaving. But we need to recognize the risks and do our best to mitigate them. This data did show that Children receive far less CT scans than adults overall, which we should be proud of. But this study is a reminder that when imaging, we still need to think twice, be judicious, use alternate imaging modalities when available, and use your evidence based guidelines to try and mitigate possible harm.
