ARRS: Disease Mortality Risk Trumps Radiation Risk

(HealthDay News) – For young adults, the risk of short-term mortality from inherent disease is larger than the predicted risk of computed-tomography (CT)-induced cancer, across all CT scanning frequencies.

Rob Zondervan, from Massachusetts General Hospital in Boston, and colleagues investigated the scanning frequency, patient outcome, and predicted cancer incidence for 8,133 18–35 year old patients who underwent chest CT and 15,226 who underwent abdomino-pelvic CT, from 2003–2007. The frequency of CT scanning was classified as very rare (one to two), rare (two to five), moderate (six to 15), and frequent (>15).

The researchers found that, after a mean of 4.2 years, 5% of very rarely, 14% of rarely, 22% of moderately, and 50% of frequently scanned patients in the chest CT cohort died. The predicted number of radiation-induced cancers in each scanning category was six, two, three, and one case, respectively, corresponding to cancer incidences of 0.08, 0.22, 0.52, and 1.13%. After a mean follow-up of 3.5 years, the corresponding proportions of deceased patients in the abdomen CT cohort were 2, 10, 17, and 33%. The predicted number of radiation-induced cancers was 14, four, four, and one, respectively, corresponding to cancer incidences of 0.1, 0.27, 0.65, and 1.4%, respectively.

"A majority of cancers are predicted to occur in the very rarely scanned. However, across all scanning frequencies, the risk of short-term mortality from inherent disease is far larger than the predicted risk of cancer induced by CT," the authors write.

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