Is there any supportive evidence for low dose radiotherapy for COVID-19 pneumonia?

Abstract

Since early April 2020, there has been intense debate over proposed clinical use of ionizing radiation to treat life-threatening pneumonia in Coronavirus Disease 2019 (COVID-19) patients. At least twelve relevant papers appeared by 20 May 2020. The radiation dose proposed for clinical trials are a single dose (0.1-1 Gy) or two doses (a few mGy followed by 0.1-0.25 Gy involving a putative adaptive response, or 1-1.5 Gy in two fractions 2-3 days apart). The scientific rationale for such proposed so-called low dose radiotherapy (LDRT) is twofold (note that only doses below 0.1 Gy are considered as low doses in the field of radiation protection, but here we follow the term as conventionally used in the field of radiation oncology). Firstly, the potentially positive observations in human case series and biological studies in rodent models on viral or bacterial pneumonia that were conducted in the pre-antibiotic era. Secondly, the potential anti-inflammatory properties of LDRT, which have been seen when LDRT is applied locally to subacute degenerative joint diseases, mainly in Germany. However, the human and animal studies cited as supportive evidence have significant limitations, and whether LDRT produces anti-inflammatory effects in the inflamed lung or exacerbates ongoing COVID-19 damage remains unclear. Therefore, we conclude that the available scientific evidence does not justify clinical trials of LDRT for COVID-19 pneumonia, with unknown benefit and known mortality risks from radiogenic cancer and circulatory disease. Despite the significant uncertainties in these proposals, some clinical trials are ongoing and planned. This paper gives an overview of current situations surrounding LDRT for COVID-19 pneumonia.

NRG Oncology Updated International Consensus Atlas on Pelvic Lymph Node Volumes for Intact and Postoperative Prostate Cancer

“…However, after the onset of effective antimicrobial agents, the use of IR in the treatment of patients has been discontinued and the involved mechanism remained unknown. Following the excess death toll related to the COVID-19 pandemic, some radiation oncologists suggested the use of low doses of RT to treat COVID-19 patients suffering from ARDS [25][26][27][28][29], even if this raised some criticism, [30][31][32][33] given the uncertainties regarding a potential viral flare-up or an increase in lung tissue damage [34]. In the absence of preclinical data, the scientific community is puzzled between the risks associated with a whole lung irradiation (acute worsening of the patients, and the immediate intrinsic risk of ARDS) [34].…”

Low doses of radiation increase the immunosuppressive profile of lung macrophages during viral infection and pneumonia

“…However, after the onset of effective antimicrobial agents, the use of IR in the treatment of patients has been discontinued and the involved mechanism remained unknown. Following the excess death toll related to the COVID-19 pandemic, some radiation oncologists suggested the use of low doses of RT to treat COVID-19 + patients suffering from ARDS (24)(25)(26)(27)(28), even if this raised some criticism, (29)(30)(31)(32) given the uncertainties regarding a potential viral flare-up or an increase in lung tissue damage. In the absence of preclinical data, the scientific community is puzzled between the risks associated with a whole lung irradiation (acute worsening of the patients, and the immediate intrinsic risk of ARDS).…”

In Reply to Taunk et al

“…[5][6][7] However, after the onset of effective antimicrobial agents, the use of IR in the treatment of patients was discontinued, and the involved mechanism remained unknown. After the excess death toll related to the COVID-19 pandemic, some radiation oncologists suggested the use of low doses of RT to treat COVID-19 patients suffering from ARDS, [25][26][27][28][29] even if this raised some criticism [30][31][32][33] given the uncertainties regarding a potential viral flare-up or an increase in lung tissue damage. 34 In the absence of preclinical data, the scientific community is torn between the risks associated with whole-lung irradiation (acute worsening of the patients), and the immediate intrinsic risk of ARDS.…”