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

Differences between Survival Rates and Patterns of Failure of Patients with Lung Adenocarcinoma and Squamous Cell Carcinoma Who Received Single-Fraction Stereotactic Body Radiotherapy

We investigated the survival and patterns of failure in adenocarcinoma (ADC) and squamous cell carcinoma (SCC) in early stage non-small cell lung cancer (NSCLC) treated with single-fraction stereotactic body radiation therapy (SF-SBRT) of 27-34 Gray. A single-institution retrospective review of patients with biopsy-proven early stage ADC or SCC undergoing definitive SF-SBRT between September 2008 and February 2023 was performed. The primary outcomes were overall survival (OS) and disease-free survival (DFS). The secondary outcomes included local failure (LF), nodal failure (NF), and distant failure (DF). Of 292 eligible patients 174 had adenocarcinoma and 118 had squamous cell carcinoma. There was no significant change in any outcome except distant failure. Patients with ADC were significantly more likely to experience distant failure than patients with SCC (p = 0.0081). In conclusion, while SF-SBRT produced similar LF, NF, DFS, and OS, the higher rate of distant failure in ADC patients suggests that ongoing trials of SBRT and systemic therapy combinations should report their outcomes by histology.

Long-Term Survival and Failure Outcomes of Single-Fraction Stereotactic Body Radiation Therapy in Early Stage NSCLC

Introduction

This study aims to report our 13-year institutional experience with single-fraction stereotactic body radiation therapy (SF-SBRT) for early stage NSCLC.

Methods

A single-institutional retrospective review of patients with biopsy-proven peripheral cT1-2N0M0 NSCLC undergoing definitive SF-SBRT between September 2008 and May 2022 was performed. All patients were treated to 27 Gy with heterogeneity corrections or 30 Gy without. Primary outcomes were overall survival and progression-free survival. Secondary outcomes included local failure, nodal failure, distant failure, and second primary lung cancer.

Results

Among 263 eligible patients, the median age was 76 years (interquartile range [IQR]: 70-81 y) and median follow-up time was 27.2 months (IQR: 14.25-44.9 mo). Median tumor size was 1.9 cm (IQR: 1.4-2.6 cm), and 224 (85%) tumors were T1. There were 92 patients (35%) alive at the time of analysis with a median follow-up of 34.0 months (IQR: 16.6-50.0 mo). Two- and five-year overall survival was 65% and 26%, respectively. A total of 74 patients (28%) developed disease progression. Rates of five-year local failure, nodal failure, distant failure, and second primary lung cancer were 12.7%, 14.7%, 23.5%, and 12.0%, respectively.

Conclusions

Consistent with multiple prospective randomized trials, in a large real-world retrospective cohort, SF-SBRT for peripheral early stage NSCLC was an effective treatment approach.

Nursing Care for Metastatic Bone Cancer: Trends for the Future

To effectively treat patients and minimize viral exposure, oncology nurses and radiology departments during COVID-19 had to re-examine the ability to offer palliative radiation treatments to people with metastatic bone cancer. Decreasing potential exposure to the virus resulted in extra measures to keep patients and personnel safe. Limiting radiotherapy treatments, social distancing, and limiting caregivers were a few of the ways that oncology patients were impacted by the pandemic. Hypofractionated radiation therapy (HFRT), or the delivery of fewer higher-dose treatments, was a method of providing care but also limiting exposure to infection for immunocompromised patients as well as healthcare staff. As oncology radiation centers measure the impact of patient care during the pandemic, a trend toward HFRT may occur in treating the painful symptoms of bone cancer. In anticipation that HFRT may be increasingly used in patient treatment plans, oncology nurses should consider patient perspectives and outcomes from the pandemic to further determine how to manage future trends in giving personalized care, and supportive care.

Long-Term Outcomes of TROG 13.01 SAFRON II Randomized Trial of Single- Versus Multifraction Stereotactic Ablative Body Radiotherapy for Pulmonary Oligometastases

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.In a randomized phase II clinical trial, the Trans Tasman Radiation Oncology Group compared single- versus multifraction stereotactic ablative body radiotherapy (SABR) in 90 patients with 133 oligometastases to the lung. The study found no differences in safety, efficacy, systemic immunogenicity, or survival between arms, with single-fraction SABR picked as the winner on the basis of cost-effectiveness. In this article, we report the final updated survival outcome analysis. The protocol mandated no concurrent or post-therapy systemic therapy until progression. Modified disease-free survival (mDFS) was defined as any progression not addressable by local therapy, or death. At a median follow-up of 5.4 years, the 3- and 5-year estimates for overall survival (OS) were 70% (95% CI, 59 to 78) and 51% (95% CI, 39 to 61). There were no significant differences between the multi- and single-fraction arms for OS (hazard ratio [HR], 1.1 [95% CI, 0.6 to 2.0]; P = .81). The 3- and 5-year estimates for disease-free survival were 24% (95% CI, 16 to 33) and 20% (95% CI, 13 to 29), with no differences between arms (HR, 1.0 [95% CI, 0.6 to 1.6]; P = .92). The 3- and 5-year estimates for mDFS were 39% (95% CI, 29 to 49) and 34% (95% CI, 24 to 44), with no differences between arms (HR, 1.0 [95% CI, 0.6 to 1.8]; P = .90). In this patient population, where patients receive SABR in lieu of systemic therapy, one-in-three patients are alive without disease in the long term. There were no differences in outcomes by fractionation schedule.

Is single fraction the future of stereotactic body radiation therapy (SBRT)? A critical appraisal of the current literature

Stereotactic Body Radiation Therapy (SBRT) is a standard of care for many localizations but the question of the optimal fractionation remains a matter of concern. If single fraction sessions are routinely used for intracranial targets, their utilization for mobile extracranial lesions is a source of debate and apprehension. Single session treatments improve patient comfort, provide a medico-economic benefit, and have proven useful in the context of the SARS-CoV 2 pandemic. However, both technical and radiobiological uncertainties remain. Experience from intracranial radiosurgery has shown that the size of the target, its proximity to organs at risk, tumor histology, and the volume of normal tissue irradiated are all determining factors in the choice of fractionation. The literature on the use of single fraction for extracranial sites is still scarce. Only primary and secondary pulmonary tumors have been evaluated in prospective randomized trials, allowing the integration of these fractionation schemes in daily practice, for highly selected cases and in trained teams. The level of evidence for the other organs is mainly based on dose escalation or retrospective trials and calls for caution, with further studies being needed before routine use in clinical practice.

Local Control With Single-Fraction Lung Stereotactic Body Radiotherapy is not influenced by Non-Small Cell Lung Cancer Histologic Subtype

INTRODUCTION/BACKGROUND

For early stage medically inoperable lung cancer treated with fractionated stereotactic body radiotherapy (SBRT), higher local failure is associated with squamous carcinoma (SqC) compared to adenocarcinoma (AC). This study explored whether histology influences single-fraction SBRT local control.

MATERIALS AND METHODS

We surveyed our prospective data registry from 12/2009 to 12/2019 for SF-SBRT cases with biopsy-proven AC or SqC only. Outcomes of interest included local (LF), nodal (NF), distant (DF) failure rates and overall survival (OS), as well as treatment-related toxicity.

RESULTS

For the 10-year interval surveyed, 113 patients met study criteria. There was no association between histology and dose received (34 Gy or 30 Gy). Median follow up was 22.9 months. Patient characteristics were balanced between histologic cohorts. Median tumor size was 1.9 cm. Comparing total AC vs. SqC cohorts, 2-year LF rates (%) were 7.3 vs. 9.6, respectively (P = .9805). In %, 2-year LF, NF, DF and OS rates for AC for 30 Gy and 34 Gy, respectively, were 10.8 vs. 6.4; 10.5 vs. 16.2; 15.8 vs. 13.0; 77.9 vs.71.2 (all P = non-significant). In %, 2-year LF, NF, DF, and OS rates for SqC for 30 Gy and 34 Gy, respectively, were 11.8 vs. 8.1; 5.9 vs. 18.0; 23.5 vs. 9.7; 70.6 vs. 77.1 (all P = non-significant). When considering toxicities, there were no grade 4/5 toxicities and no significant differences in any other toxicity rate by histology or dose.

CONCLUSION

SF-SBRT local control was not associated with histology, unlike fractionated schedules. This novel finding adds to the evolving understanding of this treatment schedule.

The role transition of radiotherapy for the treatment of liver cancer in the COVID-19 era

The uncontrollable COVID-19 crises in the SARS-CoV-2 high-prevalence areas have greatly disrupted the routine treatment of liver cancer and triggered a role transformation of radiotherapy for liver cancer. The weight of radiotherapy in the treatment algorithm for liver cancer has been enlarged by the COVID-19 pandemic, which is helpful for the optimal risk-benefit profile.

Treatment Time Optimization in Single Fraction Stereotactic Ablative Radiation Therapy: A 10-Year Institutional Experience

Purpose

Stereotactic ablative radiation therapy (SABR) delivered in a single fraction (SF) can be considered to have higher uncertainty given that the error probability is concentrated in a single session. This study aims to report the variation in technology and technique used and its effect on intrafraction motion based on a 10 years of experience in SF SABR.

Methods and Materials

Records of patients receiving SF SABR delivered at our instruction between 2010 and 2019 were included. Treatment parameters were extracted from the patient management database by using an in-house script. Treatment time was defined as the time difference between the first image acquisition to the last beam off of a single session. The intrafraction variation was measured from the 3-dimensional couch displacement measured after the first cone beam computed tomography (CBCT) acquired during a treatment.

Results

The number of SF SABR increased continuously from 2010 to 2019 and were mainly lung treatments. Treatment time was minimized by using volumetric modulated arc therapy, flattening filter-free dose rate, and coplanar field (24 ± 9 min). Treatment time increased as the number of CBCTs per session increased. The most common scenario involved both 2 and 3 CBCTs per session. On the average, a CBCT acquisition added 6 minutes to the treatment time. All treatments considered, the average intrafraction variation was 1.7 ± 1.6 mm.

Conclusions

SF SABR usage increased with time in our institution. The intrafraction motion was acceptable and therefore a single fraction is an efficacious treatment option when considering SABR.

Dosimetric effects of respiratory motion during stereotactic body radiation therapy of lung tumors

BACKGROUND

Respiratory-induced lung tumor motion may affect the delivered dose in stereotactic body radiation therapy (SBRT). Previous studies are often based on phantom studies for one specific treatment technique. In this study, the dosimetric effect of tumor motion was quantified in real patient geometries for different modulated treatments and tumor motion amplitudes for lung-SBRT.

MATERIAL AND METHODS

A simulation method using deformable image registrations and 4-dimensional computed tomographies (4DCT) was developed to assess the dosimetric effects of tumor motion. The method was evaluated with ionization chamber and Gafchromic film measurements in a thorax phantom and used to simulate the effect for 15 patients with lung tumors moving 7.3-27.4 mm. Four treatment plans with different complexities were created for each patient and the motion-induced dosimetric effect to the gross tumor volume (GTV) was simulated. The difference between the planned dose to the static tumor and the simulated delivered dose to the moving tumor was quantified for the near minimum (D_98%), near maximum (D_2%) and mean dose (D_mean) to the GTV as well as the largest observed local difference within the GTV (Max_diff).

RESULTS

No correlation was found between the dose differences and the tumor motion amplitude or plan complexity. However, the largest deviations were observed for tumors moving >15.0 mm. The simulated delivered dose was within 2.5% from the planned dose for D_98% (tumors moving <15 mm) and within 3.3% (tumors moving >15 mm). The corresponding values were 1.7% vs. 6.4% (D_2%); 1.7% vs. 2.4% (D_mean) and 8.9% vs. 35.2% (Max_diff). Using less complex treatment techniques minimized Max_diff for tumors moving >15.0 mm.

CONCLUSION

The dosimetric effects of respiratory-induced motion during lung SBRT are patient and plan specific. The magnitude of the dosimetric effect cannot be assessed solely based upon tumor motion amplitude or plan complexity.

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

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.

Single-fraction stereotactic ablative body radiation therapy for primary and metastasic lung tumor: A new paradigm?

Stereotactic ablative body radiotherapy (SABR) is an effective technique comparable to surgery in terms of local control and efficacy in early stages of non-small cell lung cancer (NSCLC) and pulmonary metastasis. Several fractionation schemes have proven to be safe and effective, including the single fraction (SF) scheme. SF is an option cost-effectiveness, more convenience and comfortable for the patient and flexible in terms of its management combined with systemic treatments. The outbreak of the severe acute respiratory syndrome coronavirus 2 pandemic has driven this not new but underutilized paradigm, recommending this option to minimize patients’ visits to hospital. SF SABR already has a long experience, strong evidence and sufficient maturity to reliably evaluate outcomes in peripheral primary NSCLC and there are promising outcomes in pulmonary metastases, making it a valid treatment option; although its use in central locations, synchronous and recurrencies tumors requires more prospective safety and efficacy studies. The SABR radiobiology study, together with the combination with systemic therapies, (targeted therapies and immunotherapy) is a direction of research in both advanced disease and early stages whose future includes SF.

Systematic Review of Single-Fraction Stereotactic Body Radiation Therapy for Early Stage Non-Small-Cell Lung Cancer and Lung Oligometastases: How to Stop Worrying and Love One and Done

Adoption of single-fraction lung stereotactic body radiation therapy (SBRT) for patients with medically inoperable early stage non-small-cell lung cancer (NSCLC) or oligometastatic lung disease, even during the coronavirus disease 2019 (COVID-19) pandemic, was limited despite encouraging phase II trial results. Barriers to using single-fraction SBRT may include lack of familiarity with the regimen and lack of clarity about the expected toxicity. To address these concerns, we performed a systematic review of prospective literature on single-fraction SBRT for definitive treatment of early stage and oligometastatic lung cancer. A PubMed search of prospective studies in English on single-fraction lung SBRT was conducted. A systematic review was performed of the studies that reported clinical outcomes of single-fraction SBRT in the treatment of early stage non-small-cell lung cancer and lung oligometastases. The current prospective literature including nine trials supports the use of single-fraction SBRT in the definitive treatment of early stage peripheral NSCLC and lung oligometastases. Most studies cite local control rates of >90%, mild toxicity profiles, and favorable survival outcomes. Most toxicities reported were grade 1–2, with grade ≥3 toxicity in 0–17% of patients. Prospective trial results suggest potential consideration of utilizing single-fraction SBRT beyond the COVID-19 pandemic.

Carbon Ion Radiotherapy Acts as the Optimal Treatment Strategy for Unresectable Liver Cancer During the Coronavirus Disease 2019 Crisis

The coronavirus disease 2019 (COVID-19) pandemic has greatly disrupted the normal treatment of patients with liver cancer and increased their risk of death. The weight of therapeutic safety was significantly amplified for decision-making to minimize the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Herein, the safety and effectiveness of carbon ion radiotherapy (CIRT) for unresectable liver cancer (ULC) were evaluated, and Chinese experiences were shared to solve the predicament of ULC treatment caused by SARS-CoV-2. Worldwide studies were collected to evaluate CIRT for ULC as the world has become a community due to the COVID-19 pandemic. We not only searched five international databases including the Cochrane Library, Web of Science, PubMed, Embase, and Scopus but also performed supplementary retrieval with other sources. Chinese experiences of fighting against COVID-19 were introduced based on the advancements of CIRT in China and a prospective clinical trial of CIRT for treating ULC. A total of 19 studies involving 813 patients with ULC were included in the systematic review. The qualitative synthetic evaluation showed that compared with transarterial chemoembolization (TACE), CIRT could achieve superior overall survival, local control, and relative hepatic protection. The systematic results indicated that non-invasive CIRT could significantly minimize harms to patients with ULC and concurrently obtain superior anti-cancer effectiveness. According to the Chinese experience, CIRT allows telemedicine within the hospital (TMIH) to keep a sufficient person-to-person physical distance in the whole process of treatment for ULC, which is significant for cutting off the transmission route of SARS-CoV-2. Additionally, CIRT could maximize the utilization rate of hospitalization and outpatient care (UHO). Collectively, CIRT for ULC patients not only allows TMIH and the maximized UHO but also has the compatible advantages of safety and effectiveness. Therefore, CIRT should be identified as the optimal strategy for treating appropriate ULC when we need to minimize the risk of SARS-CoV-2 infection and to improve the capacity of medical service in the context of the unprecedented COVID-19 crisis.

Hyperthermia ablation combined with transarterial chemoembolization versus monotherapy for hepatocellular carcinoma: A systematic review and meta-analysis

BACKGROUND AND AIMS

The existing evidence has indicated that hyperthermia ablation (HA) and HA combined with transarterial chemoembolization (HATACE) are the optimal alternative to surgical resection for patients with hepatocellular carcinoma (HCC) in the COVID-19 crisis. However, the evidence for decision-making is lacking in terms of comparison between HA and HATACE. Herein, a comprehensive evaluation was performed to compare the efficacy and safety of HATACE with monotherapy.

MATERIALS AND METHODS

Worldwide studies were collected to evaluate the HATACE regimen for HCC due to the practical need for global extrapolation of applicative population. Meta-analyses were performed using the RevMan 5.3 software (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark).

RESULTS

Thirty-six studies involving a large sample of 5036 patients were included finally. Compared with HA alone, HATACE produced the advantage of 5-year overall survival (OS) rate (OR:1.90; 95%CI:1.46,2.46; p < 0.05) without increasing toxicity (p ≥ 0.05). Compared with TACE alone, HATACE was associated with superior 5-year OS rate (OR:3.54; 95%CI:1.96,6.37; p < 0.05) and significantly reduced the incidences of severe liver damage (OR:0.32; 95%CI:0.11,0.96; p < 0.05) and ascites (OR:0.42; 95%CI:0.20,0.88; p < 0.05). Subgroup analysis results of small (≤3 cm) HCC revealed that there were no significant differences between the HATACE group and HA monotherapy group in regard to the OS rates (p ≥ 0.05).

CONCLUSIONS

Compared with TACE alone, HATACE was more effective and safe for HCC. Compared with HA alone, HATACE was more effective for non-small-sized (>3 cm) HCC with comparable safety. However, the survival benefit of adjuvant TACE in HATACE regimen was not found for the patients with small (≤3 cm) HCC.

Ten-Year Experience in Implementing Single-Fraction Lung SBRT for Medically Inoperable Early-Stage Lung Cancer

PURPOSE

To review 10 years of using single-fraction lung stereotactic body radiation therapy (SF-SBRT) for medically inoperable peripheral early-stage lung cancer.

METHODS AND MATERIALS

An institutional review board-approved prospective lung SBRT data registry was surveyed until the end of December 2019 for all patients receiving SF-SBRT with minimum 6-month follow-up. Doses used were either 34 Gy or 30 Gy. Outcomes of interest included rates of local failure and overall survival (OS), as well as treatment-related toxicity graded per Common Terminology Criteria for Adverse Events version 3.0.

RESULTS

A total of 229 patients met the study criteria. Patient characteristics included female sex (55%); median age, 74.6 years (range, 47-94); and median Karnofsky Performance Status 80 (range, 50-100). Tumor characteristics included median diameter, 1.6 cm (range, 0.7-4.1); median positron emission tomography standardized uptake value maximum 6.1 (range, 0.8-24.3); and 63.6% of patients biopsied. SF-SBRT dose was 34 Gy in 72.1% cases and 30 Gy in 27.9%, with patient and tumor characteristics balanced between cohorts. Overall median follow-up times for 30 Gy and 34 Gy were 36.7 and 17.2 months, respectively (P < .0001). At analysis, 55.9% patients were alive. Two (0.9%) patients developed grade 3 toxicities, and none had grade 4/5 toxicities. Grades 1 to 2 pneumonitis and chest wall toxicity were seen in 7% and 12.7% patients, respectively. Median overall survival was 44.1 months. Rates of 2-year local, nodal, and distant failure were 7.3%, 9.4%, and 12.2%, respectively. There were no significant differences in outcomes by dose.

CONCLUSIONS

This is the largest institutional series to date reporting on SF-SBRT outcomes for medically inoperable peripheral early-stage lung cancer and the first to report on a decade's experience in implementing this schedule. Outcomes from this analysis are comparable to published results from 2 randomized trials and validate the use of this schedule in routine practice. In the absence of phase 3 trials, this study should encourage increased use of SF-SBRT for inoperable tumors.

COVID-19 Pandemic-Adapted Radiotherapy Guidelines: Are They Really Followed?

BACKGROUND

In our department, we provided guidelines to the radiation oncologists (ROs) regarding the omission, delay, or shortening of radiotherapy (RT). The purpose was to reduce the patients' exposure to the hospital environment and to minimize the departmental overcrowding. The aim was to evaluate the ROs' compliance to these guidelines.

METHODS

ROs were asked to fill out a data collection form during patients' first visits in May and June 2020. The collected data included the ROs' age and gender, patient age and residence, RT purpose, treated tumor, the dose and fractionation that would have been prescribed, and RT changes. The chi-square test and binomial logistic regression were used to analyze the correlation between the treatment prescription and the collected parameters.

RESULTS

One hundred and twenty-six out of 205 prescribed treatments were included in this analysis. Treatment was modified in 61.1% of cases. More specifically, the treatment was omitted, delayed, or shortened in 7.9, 15.9, and 37.3% of patients, respectively. The number of delivered fractions was reduced by 27.9%. A statistically significant correlation (p = 0.028) between younger patients' age and lower treatment modifications rate was recorded.

CONCLUSION

Our analysis showed a reasonably high compliance of ROs to the pandemic-adapted guidelines. The adopted strategy was effective in reducing the number of admissions to our department.

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

PURPOSE

We report preliminary dosimetric data concerning the use of 1.5-T MR-guided daily-adaptive radiotherapy for abdomino-pelvic lymph-nodal oligometastases. We aimed to assess the impact of this technology on mitigating daily variations for both target coverage and organs-at-risk (OARs) sparing.

METHODS

A total of 150 sessions for 30 oligometastases in 23 patients were analyzed. All patients were treated with MR-guided stereotactic body radiotherapy (SBRT) for a total dose of 35 Gy in five fractions. For each fraction, a quantitative analysis was performed for PTV volume, V35Gy and D_mean. Similarly, for OARs, we assessed daily variations of volume, D_mean, D_max. Any potential statistically significant change between baseline planning and daily-adaptive sessions was assessed using the Wilcoxon signed-rank test, assuming a p value < 0.05 as significant.

RESULTS

Average baseline PTV, bowel, bladder, and single intestinal loop volumes were respectively 8.9 cc (range 0.7-41.2 cc), 1176 cc (119-3654 cc), 95 cc (39.7-202.9 cc), 18.3 cc (9.1-37.7 cc). No significant volume variations were detected for PTV (p = 0.21) bowel (p = 0.36), bladder (p = 0.47), except for single intestinal loops, which resulted smaller (p = 0.026). Average baseline V35Gy and D_mean for PTV were respectively 85.6% (72-98.8%) and 35.6 Gy (34.6-36.1 Gy). We recorded a slightly positive trend in favor of daily-adaptive strategy vs baseline planning for improved target coverage, although not reaching statistical significance (p = 0.11 and p = 0.18 for PTV-V35Gy and PTV-D_mean). Concerning OARs, a significant difference was observed in favor of daily-adapted treatments in terms of single intestinal loop D_max [23.05 Gy (13.2-26.9 Gy) at baseline vs 20.5 Gy (12.1-24 Gy); p value = 0.0377] and D_mean [14.4 Gy (6.5-18 Gy) at baseline vs 13.0 Gy (6.7-17.6 Gy); p value = 0.0003]. Specifically for bladder, the average D_max was 18.6 Gy (0.4-34.3 Gy) at baseline vs 18.3 Gy (0.7-34.3 Gy) for a p value = 0.28; the average D_mean was 7.0 Gy (0.2-16.6 Gy) at baseline vs 6.98 Gy (0.2-16.4 Gy) for a p value = 0.66. Concerning the bowel, no differences in terms of D_mean [4.78 Gy (1.3-10.9 Gy) vs 5.6 Gy (1.4-10.5 Gy); p value = 0.23] were observed between after daily-adapted sessions. A statistically significant difference was observed for bowel D_max [26.4 Gy (7.7-34 Gy) vs 25.8 Gy (7.8-33.1 Gy); p value = 0.0086].

CONCLUSIONS

Daily-adaptive MR-guided SBRT reported a significantly improved single intestinal loop sparing for lymph-nodal oligometastases. Also, bowel D_max was significantly reduced with daily-adaptive strategy. A minor advantage was also reported in terms of PTV coverage, although not statistically significant.

Radiotherapy based management during Covid-19 pandemic - A systematic review of presented consensus and guidelines

Treatment management of cancer patients in the radiation oncology departments during the current COVID-19 pandemic is challenging. A systematic review of published consensus/guidelines on the role of radiotherapy prioritization, suggested treatment protocols, and set up management was undertaken based on the PRISMA protocol and through PubMed/PMC, Scopus, Google Scholar, Web of Science databases until 01/20/2021. One hundred and sixty-eight publications or regional consensus were included. Summary of recommendations contained: (1) using hypo-fractionated (Hypo-F) regimens for therapeutic/palliative indications, (2) delaying radiotherapy for several weeks or until pandemic over, (3) omitting radiotherapy by replacement of alternative therapies or active surveillance, (4) applying safer patients' setup and preparation protocols, (5) developing telemedicine/telehealth service. To conclude, it is essential to carefully weigh the risk of exposure to COVID-19 infection and the benefit of treating cancer patients during the pandemic. Trying to have a global guideline facing this or any other probable crisis is crucial for health care service.

A multi-institutional analysis of fractionated versus single-fraction stereotactic body radiotherapy (SBRT) in the treatment of primary lung tumors: a comparison between two antipodal fractionations

OBJECTIVES

Stereotactic body radiotherapy (SBRT) is a consolidate treatment for inoperable early-stage lung tumors, usually delivered in single or multi-fraction regimens. We aimed to compare these two approaches in terms of local effectiveness, safety and survival.

MATERIALS AND METHODS

Patients affected by medically inoperable early-stage lung tumor were treated at two Institutions with two different schedules: 70 Gy in ten fractions (TF) (BED10: 119 Gy) or 30 Gy in single fraction (SF) (BED10: 120 Gy).

RESULTS

73 patients were treated with SBRT delivered with two biological equivalent schedules: SF (44) and TF (29). The median follow-up was 34 months (range 3-81 months). Three-year Overall survival (OS) was 57.9%, 3-year cancer-specific survival (CSS) was 77.2%, with no difference between treatment groups. Three-year progression-free survival (LPFS) was 88.9% and did not differs between SF and TF. Overall, four cases (5.4%) of acute grade ≥ 3 pneumonitis occurred. No differences in acute and late toxicity between the two groups were detected.

CONCLUSION

SF and TF seems to be equally safe and effective in the treatment of primary inoperable lung tumors especially for smaller lesion. The SF may be preferentially offered to reduce patient access to hospital with no negative impact on tumor control and survival.

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

Stereotactic ablative body radiation therapy (SABR) is a well-established alternative to surgery for early stage non-small-cell lung cancer (NSCLC). While SABR is typically delivered in 3 to 5 fractions, randomized trials have shown single-fraction SABR to be a reasonable alternative. We present the case of a 66-year-old male with history of cholangiocarcinoma who was subsequently diagnosed with peripheral early stage NSCLC and treated in mid-inspiration breath hold (BH) to 34 Gy in 1 fraction on a magnetic resonance (MR)-guided linear accelerator, with treatment delivery completed in 17 minutes. Visual biofeedback was utilized to maximize patient compliance with appropriate depth of inspiration BH and improve overall treatment delivery time efficiency. The benefits of single- vs multifraction SABR and unique advantages of MR guidance that are particularly well-suited for single-fraction SABR are reviewed.

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

Purpose

Although SABR can improve oncologic outcomes for patients with oligometastatic disease, treatment of metastases near critical organs remains challenging. The purpose of this study is to determine the dosimetric feasibility of delivering magnetic resonance imaging (MRI)-guided adaptive SABR in a single fraction for abdominal and thoracic metastases.

Methods and Materials

Previously delivered MRI-guided radiation therapy plans for 20 patients with oligometastatic disease in the thorax or abdomen, with 70% (14/20) of the lesions within 8 mm from dose-limiting organs at risk (OARs), were used to simulate the delivery of 24 Gy in a single fraction. Planning objectives included planning target volume (PTV) V_95% >90%, optimized PTV (PTVopt) V_95% >90%, and PTVopt D_99% >20 Gy with no OAR dose violations, where PTVopt removed overlap with nearby planning organ at risk volume (PRV). Single-fraction plans were simulated on the first 5 daily setup breath-hold MRI scans, and the plans were reoptimized to consider variations in setup position and anatomy.

Results

The mean PTV V_95% for single-fraction SABR plans was lower compared with multifraction plans (mean 85.4% vs 92.6%, P = .02), but mean PTVopt V_95% was not different (95.3% vs 98.2%, P = .62). After reoptimization of the single-fraction plan to the treatment day MRI, there was an increase in mean PTV V_95% (85.0% vs 88.1%, P = .05), increase in mean PTVopt V_95% (92.7% vs 96.3%, P = .02), increase in mean PTVopt D_99% (19.7 Gy vs 23.8 Gy, P < .01), increase in mean frequency of meeting PTV D_99% >20 Gy (52% vs 87%, P < .01), and increase in mean gross tumor volume minimum dose (17.5 Gy vs 19.3 Gy, P < .01). Reoptimization decreased mean frequency of OAR dose constraint violation (48% vs 0%, P < .01).

Conclusions

Single-fraction MRI-guided SABR is a dosimetrically feasible treatment for oligometastases that allows for on-table adaptation to avoid OAR dose constraint violations, but this method requires clinical validation.