Perioperative Abdominopelvic CT tied to development of Hematologic Malignant Neoplasms

It was a nationwide population-based cohort study in which researchers used the National Health Insurance Service claims database in South Korea to assess 825 820 patients who underwent appendectomy for appendicitis from January 1, 2005, to December 31, 2015, and who had no underlying risk factors for cancer. They divided the patients into CT-exposed (n = 306 727) and CT-unexposed (n = 519 093) groups. The major outcome assessed was the incidence rate ratio (IRR) of hematologic malignant neoplasms for both groups. IRR of abdominopelvic organ cancers and IRR of all cancers were also assessed. Researchers used Poisson regression models with adjustment for age and sex to calculate the IRR.

Key findings of the study were:

• Researchers observed the development of hematologic malignant neoplasms in 323 patients in the CT-exposed group during 1 486 518 person-years and 500 patients in the CT-unexposed group during 3 422 059 person-years.

• They noted that for all hematologic malignant neoplasms, the IRR for the CT-exposed vs CT-unexposed group was 1.26.

• They also noted that incidence of hematologic malignant neoplasms tended to increase with the number of abdominopelvic CT examinations.

• They found that the carcinogenic risk from abdominopelvic CT radiation was most pronounced in patients aged 0 to 15 years (IRR, 2.14).

• In terms of individual categories of hematologic malignant neoplasms, they found the CT-exposed group had an elevated risk only for leukemia (IRR, 1.40).

• However, they found no difference between groups in the incidence rate of abdominopelvic organ cancers (IRR, 1.07) and that of all cancers (IRR, 1.04).

The authors concluded, "This study controlled for reverse causation bias by defining the reasons for CT scan, and findings suggest that abdominopelvic CT radiation is associated with a higher incidence of hematologic malignant neoplasms. Efforts should be continued for judicious use of CT examinations".

For further information:

https://jamanetwork.com/journals/jamasurgery/fullarticle/2775351