Single-Fraction Stereotactic Body Radiation Therapy: A Paradigm During the Coronavirus Disease 2019 (COVID-19) Pandemic and Beyond?

Abstract

Purpose Owing to the coronavirus disease 2019 (COVID-19) pandemic, radiation oncology departments have adopted various strategies to deliver radiation therapy safely and efficiently while minimizing the risk of severe acute respiratory syndrome coronavirus–2 transmission among patients and health care providers. One practical strategy is to deliver stereotactic body radiation therapy (SBRT) in a single fraction, which has been well established for treating bone metastases, although it has been infrequently used for other extracranial sites. Methods and Materials A PubMed search of published articles in English related to single-fraction SBRT was performed. A critical review was performed of the articles that described clinical outcomes of single-fraction SBRT for treatment of primary extracranial cancers and oligometastatic extraspinal disease. Results Single-fraction SBRT for peripheral early-stage non-small cell lung cancer is supported by randomized data and is strongly endorsed during the COVID-19 pandemic by the European Society for Radiotherapy and Oncology-American Society for Radiation Oncology practice guidelines. Prospective and retrospective studies supporting a single-fraction regimen are limited, although outcomes are promising for renal cell carcinoma, liver metastases, and adrenal metastases. Data are immature for primary prostate cancer and demonstrate excess late toxicity in primary pancreatic cancer. Conclusions Single-fraction SBRT should be strongly considered for peripheral early-stage non-small cell lung cancer during the COVID-19 pandemic to mitigate the potentially severe consequences of severe acute respiratory syndrome coronavirus–2 transmission. Although single-fraction SBRT is promising for the definitive treatment of other primary or oligometastatic cancers, multi-fraction SBRT should be the preferred regimen owing to the need for additional prospective evaluation to determine long-term efficacy and safety.

Case report of visual biofeedback-driven, magnetic resonance-guided single-fraction SABR in breath hold for early stage non–small-cell lung cancer

“…16 This may be related to a perceived increased risk of a geographic miss as well as increased toxicity when treating in a large single fraction, however these concerns have not been substantiated in published clinical outcomes. 5 In fact, several randomized single-vs multifraction trials for peripheral early stage NSCLC reported no significant difference in outcomes with long-term follow-up. 6 , 7 MR-guided SABR could facilitate broader use of single-fraction treatment by providing increased operator confidence in the accuracy of beam delivery to the target lesion throughout treatment by means of continuous intrafraction visualization with cine-MR. 13 Moreover, the streamlined workflow for treating in BH, or gated free breathing, without fiducial markers can substantially reduce the volume of normal tissue unnecessarily irradiated, and thus decrease the potential risk for serious toxicity.…”

“…15 Image guidance, immobilization techniques, and motion management strategies have since evolved that facilitate the use of singlefraction SABR, which has the advantages of increased patient convenience, reduced cost, increased departmental patient throughput, and potential synergy with immunotherapy. 5 In the COVID-19 pandemic, we were prompted to treat selected patients with a single fraction to minimize exposure of patients to the hospital environment and thus the risk of SARS-CoV-2 infection, as well as to reduce our staffing and personal protective equipment needs when both of those resources were already constrained.…”

Mitigation on bowel loops daily variations by 1.5-T MR-guided daily-adaptive SBRT for abdomino-pelvic lymph-nodal oligometastases

“…[31,32] Based on this background, we hypothesized to investigate a dose escalated SBRT schedule which is currently ongoing at our department, aiming also to reduce the sessions, in agreement with the growing literature in support of the single-fraction treatment of oligometastases. [33,34]…”

In Silico Single-Fraction Stereotactic Ablative Radiation Therapy for the Treatment of Thoracic and Abdominal Oligometastatic Disease With Online Adaptive Magnetic Resonance Guidance

“…Future studies using MR-guided single-fraction SABR was recommended for the treatment of central lung cancers and liver metastases close to the portal vein and gastrointestinal tract. 11 …”