Low-Dose CT Screening Does Not Damage Chromosomal DNA

Lung cancer screening using low-dose chest computed tomography (CT) does not biologically affect human DNA, according to a new study.

Researchers at Hiroshima University (Japan) and Fukushima Medical University (FMU; Japan) conducted a study that compared DNA in 107 patients who underwent low-dose chest CT with that of 102 patients who had standard-dose chest CT; the median effective radiation dose of low-dose CT was 1.5 millisieverts (mSv), while that of the standard CT dose was 5.0 mSv. In addition, blood samples were obtained before and 15 minutes after CT to identify DNA double-strand breaks and chromosome aberrations (CAs) in peripheral blood lymphocytes.

The results revealed that the number of double-strand DNA breaks and CAs increased after the standard dose CT examination, but that the number of double-strand breaks and CAs before and after low dose CT remained the same. The researchers stressed that while the study does not endorse lung cancer screening with low-dose CT, its results could allay concerns over a potential increase in radiation-related cancer risk related to screening programs. The study was published on March 10, 2020, in Radiology.

“We could clearly detect the increase of DNA damage and chromosome aberrations after standard chest CT. In contrast, no significant differences were observed in these biological effects before and after low-dose CT,” said senior author Satoshi Tashiro, MD, PhD, director of the Research Institute for Radiation Biology and Medicine at Hiroshima University. “Even using these sensitive analyses, we could not detect the biological effects of low-dose CT scans. This suggests that application of low-dose CT for lung cancer screening is justified from a biological point of view.”

In Japan, low-dose CT screening has been employed since the 1990s. However, unlike other countries, examinees include light smokers and non-smokers. As a result, a large number of stage one lung cancers are detected, and the survival rate is high.

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Hiroshima University
Fukushima Medical University