Pneumonia After Bacterial or Viral Infection Preceded or Followed by Radiation Exposure: A Reanalysis of Older Radiobiologic Data and Implications for Low-Dose Radiation Therapy for Coronavirus Disease 2019 Pneumonia

Introduction Following the Covid-19 pandemic spread, changes in clinical practice were necessary to limit the pandemic diffusion. Also, oncological practice has undergone changes with radiotherapy (RT) treatments playing a key role. Although several experiences have been published, the aim of this review is to summarize the current evidence after 2 years of pandemic to provide useful conclusions for clinicians. Methods A Pubmed/MEDLINE and Embase systematic review was conducted. The search strategy was “Covid AND Radiotherapy” and only original articles in the English language were considered. Results A total of 2.733 papers were obtained using the mentioned search strategy. After the complete selection process, a total of 281 papers were considered eligible for the analysis of the results. Discussion RT has played a key role in Covid-19 pandemic as it has proved more resilient than surgery and chemotherapy. The impact of the accelerated use of hypofractionated RT and telemedicine will make these strategies central also in the post-pandemic period.

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“…These studies suggest that RT may have the best benefit-risk balance for older patients with low baseline risk factors [ 192 , 193 ].…”

Section: Resultsmentioning

confidence: 99%

Covid-19 and radiotherapy: a systematic review after 2 years of pandemic

Piras¹,

Venuti

D’Aviero³

et al. 2022

Clin Transl Imaging

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“…Historical review for LDRT does not provide evidence for morbidity or mortality associated with post-infection radiation exposure, thus the possible potential risks from low-dose lung irradiation remain unclear [92][93][94]. Therefore, the quantitative comparison of benefits and risks will assist clinical institutions in the decision of including it in the treatment management system.…”

Section: Discussionmentioning

confidence: 99%

The Role of Ionizing Radiation for Diagnosis and Treatment against COVID-19: Evidence and Considerations

Chalkia

Arkoudis

Maragkoudakis

et al. 2022

Cells

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The Coronavirus disease 2019 (COVID-19) pandemic continues to spread worldwide with over 260 million people infected and more than 5 million deaths, numbers that are escalating on a daily basis. Frontline health workers and scientists diligently fight to alleviate life-threatening symptoms and control the spread of the disease. There is an urgent need for better triage of patients, especially in third world countries, in order to decrease the pressure induced on healthcare facilities. In the struggle to treat life-threatening COVID-19 pneumonia, scientists have debated the clinical use of ionizing radiation (IR). The historical literature dating back to the 1940s contains many reports of successful treatment of pneumonia with IR. In this work, we critically review the literature for the use of IR for both diagnostic and treatment purposes. We identify details including the computed tomography (CT) scanning considerations, the radiobiological basis of IR anti-inflammatory effects, the supportive evidence for low dose radiation therapy (LDRT), and the risks of radiation-induced cancer and cardiac disease associated with LDRT. In this paper, we address concerns regarding the effective management of COVID-19 patients and potential avenues that could provide empirical evidence for the fight against the disease.

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“…Studies on noncancer effects that occur years or decades after radiation exposure are very important not only in the field of radiation protection (where lifetime risk matters), but also in medicine (particularly after radiotherapy): given that the dose threshold for noncancer effects generally decreases with increasing post-irradiation time, the longer the post-radiotherapeutic survival of patients, the broader the spectrum of normal tissue complications of concern (196). Such viewpoints would be needed to consider whether clinical benefits outweigh risks of normal tissue complications (DCS and other life-threatening noncancer diseases as well as secondary cancer) after radiotherapy, e.g., in considering justification of radiotherapy for noncancer diseases, such as coronavirus disease 2019 (COVID-19) pneumonia (197)(198)(199)(200)(201)(202), refractory ventricular tachycardia (192,193), dementia and Alzheimer's disease (203)(204)(205). This section considers late occurring noncancer effects on the radar other than those on the eye and the circulatory system.…”

Section: Other Late-occurring Noncancer Effects On the Radarmentioning

confidence: 99%

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

Hamada

2023

Radiation Research

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For radiation protection purposes, noncancer effects with a threshold-type dose-response relationship have been classified as tissue reactions (formerly called nonstochastic or deterministic effects), and equivalent dose limits aim to prevent occurrence of such tissue reactions. Accumulating evidence demonstrates increased risks for several late occurring noncancer effects at doses and dose rates much lower than previously considered. In 2011, the International Commission on Radiological Protection (ICRP) issued a statement on tissue reactions to recommend a threshold of 0.5 Gy to the lens of the eye for cataracts and to the heart and brain for diseases of the circulatory system (DCS), independent of dose rate. Literature published thereafter continues to provide updated knowledge. Increased risks for cataracts below 0.5 Gy have been reported in several cohorts (e.g., including in those receiving protracted or chronic exposures). A dose threshold for cataracts is less evident with longer follow-up, with limited evidence available for risk of cataract removal surgery. There is emerging evidence for risk of normal-tension glaucoma and diabetic retinopathy, but the long-held tenet that the lens represents among the most radiosensitive tissues in the eye and in the body seems to remain unchanged. For DCS, increased risks have been reported in various cohorts, but the existence or otherwise of a dose threshold is unclear. The level of risk is less uncertain at lower dose and lower dose rate, with the possibility that risk per unit dose is greater at lower doses and dose rates. Target organs and tissues for DCS are also unknown, but may include heart, large blood vessels and kidneys. Identification of potential factors (e.g., sex, age, lifestyle factors, coexposures, comorbidities, genetics and epigenetics) that may modify radiation risk of cataracts and DCS would be important. Other noncancer effects on the radar include neurological effects (e.g., Parkinsonŉs disease and dementia) of which elevated risk has increasingly been reported. These late occurring noncancer effects tend to deviate from the definition of tissue reactions, necessitating more scientific developments to reconsider the radiation effect classification system and risk management. This paper gives an overview of historical developments made in ICRP prior to the 2011 statement and an update on relevant developments made since the 2011 ICRP statement.

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Pneumonia After Bacterial or Viral Infection Preceded or Followed by Radiation Exposure: A Reanalysis of Older Radiobiologic Data and Implications for Low-Dose Radiation Therapy for Coronavirus Disease 2019 Pneumonia

Cited by 11 publications

References 28 publications

Covid-19 and radiotherapy: a systematic review after 2 years of pandemic

Covid-19 and radiotherapy: a systematic review after 2 years of pandemic

The Role of Ionizing Radiation for Diagnosis and Treatment against COVID-19: Evidence and Considerations

Noncancer Effects of Ionizing Radiation Exposure on the Eye, the Circulatory System and beyond: Developments made since the 2011 ICRP Statement on Tissue Reactions

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