Radiation Induced Lung Injury (RILI) and COVID-19 Pneumonia: Are There Similarities by The Radiation Oncologist’s Point of View?

Abstract

Coronavirus disease 2019 (COVID-19), is a novel infectious disease responsible for a severe acute respiratory syndrome due to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, which was firstly reported in January 2020 in Wuhan, Hubei Province, China, and then rapidly spread to other countries beyond China with a pandemic proportion in these last two years. In its severe lung expression, disease onset may result in death due to massive alveolar damage and progressive respiratory failure due to acute lung injury (ALI) which predisposes to fatal acute respiratory distress syndrome (ARDS). Autopsies reports describe a diffuse alveolar damage with vascular congestion, inflammatory cell population entrapped, thrombosis with hyaline membrane formation in the alveolar walls allowing to an irreversible lung destruction. Altogether these findings remind the radiation oncologists many similarities with radiation induced lung injury which is a well-known side effect of radiotherapy for lung cancer. A fascinating hypothesis is that a common inflammatory paradoxical response of lung could be underlying the injury whatever the causes may be, virus, drugs or ionizing radiation. In this paper we will review the similarities between these two illnesses just going through the mechanisms of ALI-ARDS and the role of the most important immune cells and cytokines involved.