Estimated Lifetime Attributable Cancer Risk From Abdominal/Pelvic CT

Source: Aloufi KM. Estimation of lifetime attributable cancer risk from abdominal-pelvic pediatric CT procedures. J Radiation Research and Applied Sciences. 2025;18(1):101261; doi: 10.1016/j.jrras.2024.101261.An investigator from Taibah University, Medina, Saudi Arabia, conducted a study to estimate the lifetime attributable risk (LAR) of cancer from abdominal or pelvic pediatric computed tomography (CT). Study participants were 120 patients <15 years old who underwent abdominal/pelvic CT in Medina, Saudi Arabia, between January to March 2024, including 30 in each of the following 4 age groups: <1 year, 1 to <5 years, 5 to <10 years, and 10 to <15 years of age. Multiple parameters from the CT in each study child (eg, length of scan) were abstracted. These values were used to calculate the equivalent dose of radiation to each exposed organ in the CT and overall effective dose. The average equivalent and effective radiation doses from the CT among males and females in each age group were estimated. To estimate the LAR of cancer incidence and mortality from exposure to radiation, data from the BEIR VII report (2006) from the World Health Organization were used. In this report, the LAR per 100,000 persons of various organs exposed to an equivalent dose of 100 mSv of radiation are provided. For the current study, the estimated calculated dose from an abdominal/pelvic CT on each exposed organ, among males and females, from each of the 4 age groups, was used in the formula LAR = equivalent dose (mSv)/100 mSv x LAR for 100,000 persons exposed to 100 mSv. The overall LAR for cancer incidence and mortality were also estimated.The average estimated effective dose of radiation from an abdominal/pelvic CT was 3.97 mSv in males <1 year old and 4.43 among females in that age group. The effective dose in males and females, respectively, in the other age groups were 4.35 and 4.9 for those 1 to <5 years, 4.52 and 5.2 for children 5 to <10 years, and 4.36 and 4.9 for those 10 to <15 years of age. Among exposed organs, the colon received the highest equivalent dose of radiation, with estimated doses ranging from 8.49 to 11.27 mSv. Using these values, the highest LAR among the exposed organs was for colon cancer among both males and females, with LARs for incidence ranging from 14.8 cases per 100,000 persons in females 10 to <15 years old to 32.1/100,000 in males 5 to <10 years old. LAR of colon cancer mortality ranged from 6.8 to 15.6/100,000. Overall, the LAR for all cancers ranged from 63 to 220.3/100,000 persons across the 4 age groups and genders, and the LAR for mortality ranged from 31 to 82.5/100,000.The author concludes that an abdominal/pelvic CT in a pediatric patient was estimated to infer a very low LAR of cancer.Dr Hogan has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Abdominal/pelvic CT is cross-sectional imaging using ironizing radiation and computer reconstruction to develop detailed, multiplanar views of the body.1 IV iodine-based contrast media is used alone (less radiation) or in combination without contrast (more radiation) to provide organ enhancement, depending on the indications.2 There are numerous life-saving indications for abdominal/pelvic CT, especially in childhood cancer detection, staging, and response to and complications from therapy.3Potential carcinogenic risks from CT are derived from a linear no-threshold hypothesis resulting from any dose of radiation, including natural background and man-made radiation sources.4 To reduce CT-related radiation exposure and optimize image quality in the US, the National Council on Radiation Protection and Measurements5 and the Image Gently Alliance6 have reported on relative risks of evolving medical radiation exposures, indications, and guidelines based on patient age, size, and radiation-sensitivity of tissues imaged.5,6 Minimizing recurrent radiation exposure also may be accomplished with MRI or ultrasonography when appropriate.3The current study is an estimated LAR from a small patient population outside the US and does not consider indications for imaging, whether with or without IV contrast, size of child, or presence of cancer predisposition syndromes.1-4 The author combined different types of CT protocols, CT models, thickness of slice, techniques, currents, and tube potentials, thus making the results difficult to interpret.5 The BEIR VII report used in this study is an estimate of cancer incidence based on historical data, with the caveat, “There be follow-up studies of cohorts of persons receiving CT scans, especially children.”4 The current researchers focused on age and gender, yet diagnostic reference levels and achievable doses for pediatric CT scans also are functions of patient size.2Although the radiation exposure from a single pediatric abdominal/pelvic CT scan potentially confers a low LAR of cancer, it is imperative that physicians monitor and improve pediatric CT protocols and scanners to limit exposure.1-6