The risk of induced cancer and ischemic heart disease following low dose lung irradiation for COVID-19: estimation based on a virtual case

Abstract

Background

Recently, low dose radiotherapy delivered to the whole lung has been proposed as treatment for the pneumonia due to COVID-19. Although there is biological plausibility for its use, the evidence supporting its effectiveness is scarce, and the risks associated with it may be significant. Thus, based on a virtual case simulation, we estimated the risks of radiation-induced cancer (RIC) and cardiac disease.

Methods

Lifetime attributable risks (LAR) of RIC were calculated for the lung, liver, esophagus, and breast of female patients. The cardiovascular risk of exposure-induced death (REID) due to ischemic heart disease was also calculated. The doses received by the organs involved in the treatment were obtained from a simulation of conformal radiotherapy (RT) treatment, delivering a dose of 0.5 Gy–1.5 Gy to the lungs. We considered a LAR and REID <1% as acceptable, 1–2% cautionary, and >2% unacceptable.

Results

The lung was at the highest risk for RIC (absolute LAR below 5200 cases/100,000 and 2250 cases/100,000 for women and men, respectively). For women, the breast had the second-highest LAR, especially for young women. The liver and esophagus had LARs below 700/100,000 for both sexes, with a higher incidence of esophageal cancer in women and liver cancer in men. Regarding the LAR cutoff, we observed an unacceptable or cautionary LAR for lung cancer in all women and men <60 years with an RT dose >1 Gy. LAR for lung cancer with an RT dose of 1 Gy was cautionary for women >60 years of age and men <40 years of age. No LAR estimation was unacceptable for the RT dose ≤0.7 Gy in all groups irrespective of sex or age at exposure. Only 0.5 Gy had an acceptable REID.

Conclusions

A RT dose ≤0.5 Gy provides an acceptable LAR estimate (≤1%) for RIC and REID, irrespective of sex and age. The current ongoing trials should initially use doses ≤0.5 Gy to maintain the risks at an acceptable level and include only patients who fail or do not have any other treatment option.

Keywords:

• COVID-19
• radiotherapy
• cancer induction
• whole lung irradiation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Gustavo Viani Arruda

Gustavo Viani, Ph.D., is a professor at the Medical School of Ribeirao Preto – University of Sao Paulo. He is head of the Radiotherapy service at the Ribeirão Preto Medical School Hospital and Clinics, University of São Paulo, Ribeirão Preto – SP, Brazil.

Raissa Renata dos Santos Weber

Raissa Renata dos Santos Weber, B.Sc, is a master’s degree student in Physics Applied to Medicine and Biology at the Faculty of Philosophy, Sciences, and Letters at Ribeirao Preto – University of Sao Paulo, Brazil.

Alexandre Colello Bruno

Alexandre Colello Bruno received his B.Sc. degree in physics and his M.Sc. and Ph.D. degrees in physics applied to medicine and biology from the University of São Paulo, Ribeirão Preto, SP, Brazil, in 2007, 2010, and 2015, respectively. During his Ph. D. studies, he was a visiting student at the University of Texas at Austin for seven months. His research interests are ultrasound, and magnetic transducers, biomedical instrumentation, image and signal processing, radiotherapy, and metrology applied to medical device development. Currently, he is a Medical Physicists at the Ribeirão Preto Medical School Hospital and Clinics, University of São Paulo, Ribeirão Preto – SP, Brazil.

Juliana Fernandes Pavoni

Juliana Fernandes Pavoni, Ph.D., is a professor at the Department of Physics, Faculty of Philosophy, Sciences and Letters at Ribeirao Preto – University of Sao Paulo. And a Medical Physicist at the Ribeirão Preto Medical School Hospital and Clinics, University of São Paulo, Ribeirão Preto – SP, Brazil.