CT coronary calcium screening leads to increased cancer risk

An analysis of a computer-based model suggests CT-based coronary calcium screening puts patients at an increased risk of developing cancer over time. Women face the greatest lifetime risk, according to researchers.

First with electron-beam CT and later with multislice CT, coronary calcium screening has earned credibility as a surrogate marker for coronary atherosclerosis and as a predictor of cardiovascular disease. The clinical literature keeps adding evidence of the test's value, particularly in patients who might be considered at low risk by conventional exams.

However, the possibility that coronary calcium screening with CT could expose patients to a higher risk of developing cancer has not been fully evaluated against the modality's perceived benefits, according to principal investigator Kwang Pyo Kim, Ph.D., a researcher at the Kyung Hee University in Seoul, Korea.

Kim and colleagues at the National Cancer Institute and Columbia University developed a computerized model that estimated the lifetime risk of radiation-induced cancer in patients who have undergone coronary calcium scoring. They analyzed hundreds of cases from the clinical literature, including data on several different CT scanners and imaging protocols.

The investigators found that coronary calcium scoring with CT could lead to an estimated 42 additional radiation-induced cancer cases per 100,000 men and 62 cases per 100,000 women if subjects underwent screening at five-year intervals starting at age 45. Findings appeared in the July 13 issue of the Archives of Internal Medicine.

An accurate description of the risks, benefits, and costs associated with CT-based coronary calcium screening in asymptomatic individuals remains elusive, according to Dr. Raymond J. Gibbons, a professor of medicine at the Mayo Clinic in Rochester, MN. In an editorial in the same issue of the publication, Gibbons and colleague Dr. Thomas C. Gerber acknowledged Kim's work as a step in that direction.

"For patients in whom coronary artery calcium scoring is considered, healthcare providers should ideally discuss the potential risks and benefits of the procedure… This discussion should include the small radiation and cancer risk described by Kim et al," the physicians wrote.