Exposure to radiation from CT scans may increase cancer risk

Study suggests cumulative exposure to radiation from CT scans may increase cancer risk

HealthDay (3/31, Reinberg) reported, "Cumulative exposure to radiation from CT scans can increase the risk for cancer by as much as 12 percent," according to research published in the April issue of Radiology. Dr. Aaron Sodickson, assistant director of emergency radiology at Brigham and Women's Hospital in Boston, and colleagues, examined medical records for "31,462 people who had undergone a total of 190,712 CT scans over 22 years." The records showed that "about 33 percent had five or more scans, five percent had more than 22, and one percent had more than 38." Overall, "15 percent of the people in the study had received cumulative radiation doses of more than 100 millisieverts (mSv), the same level of radiation as 1,000 chest X-rays." 
  WebMD (3/31, Boyles) reported that "four percent of patients had lifetime exposures equivalent to 2,500 conventional chest X-rays." Based on "a cancer risk assessment model," the researchers discovered that "7.3 percent of the study participants had an elevated risk of cancer because of radiation from CT scans." And, although "the risk was very small for most patients, totaling just one percent over the average lifetime risk of 42 percent," an estimated one percent "of the patients in the study had CT-related elevations in risk of between 2.7 percent and 12 percent." 
  The researchers found that with the size of the study's cohort, "baseline cancer rates predict 13,214 cancers, including 6,292 fatal cancers," MedPage Today (3/31, Fiore) reported. But, "CT imaging will produce 98 additional radiation-induced cancers, including 62 fatal cancers" in the cohort, based on "lifetime attributable risk calculations," the study showed. Notably, "40 percent of the subgroup with a risk estimate one percent above baseline have no history of malignancy or a cancer history with no evidence of active disease." The researchers concluded that "a risk-benefit decision must be made at the level of the individual patient," taking into account "patient-specific cumulative risks."