Stereotactic Body Radiotherapy for Lung Oligo-metastases: Systematic Review and International Stereotactic Radiosurgery Society Practice Guidelines

Pulmonary Stereotactic Body Radiation Therapy of Oligometastatic Head-and-Neck Squamous Cell Carcinoma: A Multicenter Retrospective Study

PURPOSE

The value of stereotactic body radiation therapy (SBRT) in patients with oligometastatic head-and-neck squamous cell carcinoma (HNSCC) remains unclear, as existing evidence is primarily derived from retrospective single-center analyses with small patient cohorts. This study aimed to evaluate the outcomes of pulmonary SBRT in patients with oligometastatic HNSCC and to identify factors associated with survival.

METHODS AND MATERIALS

This trinational multicenter cohort study, including 16 centers from Germany, Austria, and Switzerland, retrospectively analyzed patients with oligometastatic HNSCC undergoing SBRT for pulmonary metastases between 2010 and 2023. The primary outcome was overall survival (OS). Secondary outcomes included progression-free survival and incidence of local failures.

RESULTS

A total of 178 patients with 284 irradiated lung metastases were analyzed. The most common primary HNSCC subsites were oropharyngeal (n = 71), laryngeal (n = 37), and hypopharyngeal (n = 31). Lung metastases were treated with a median biologically effective dose (BEDα/β=10 Gy) of 105 Gy (IQR, 84-113) at the planning target volume periphery. After a median follow-up of 40 months (95% CI, 34-46), the median OS and progression-free survival were 33 months (95% CI, 26-40) and 9 months (95% CI, 7-11), respectively. The 1-year cumulative incidence of local failures was 5.5% (95% CI, 3.2-8.8). One patient (0.6%) developed acute grade 3 dysphagia, and among 146 patients assessed for chronic toxicities, 2 (1.4%) experienced grade 3 events, with no grade 4-5 toxicities. On multivariable analysis, older (>65 years) patients (hazard ratio [HR], 1.59; 95% CI, 1.02-2.49; P = .040) and females (HR, 1.76; 95% CI, 1.04-2.99; P = .035) exhibited worse OS, whereas longer time between HNSCC diagnosis and first SBRT was associated with longer OS (HR, 0.99; 95% CI, 0.99-1.00; P = .045).

CONCLUSION

SBRT for pulmonary metastases achieves excellent local control with minimal toxicity in patients with oligometastatic HNSCC. Prospective trials are needed to determine the optimal timing for integrating SBRT with systemic treatment.

Stereotactic Body Radiation therapy for Liver Metastases: Systematic Review and Meta-Analysis With International Stereotactic Radiosurgery Society (ISRS) Practice Guidelines

PURPOSE

Liver metastases are a significant clinical challenge in cancer management, often representing a stage of disease in which curative treatment is still possible. Stereotactic body radiation therapy (SBRT) has emerged as a promising modality for treating these metastases, offering a noninvasive approach with potential for high efficacy. This systematic review and meta-analysis provides a comprehensive analysis of the efficacy and safety of SBRT in treating liver metastases, and practice recommendations are provided.

METHODS AND MATERIALS

We performed a thorough literature review, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach, and included 33 studies with a total of 3101 patients and 4437 liver metastases.

RESULTS

The review revealed pooled local control rates at 1, 2, and 3 years of 85%, 75%, and 68% respectively, while overall survival rates were 79%, 54%, and 37%. Grade 3 and 4 side effects occurred in only 3% of patients. The review of the studies highlighted the importance of factors such as primary tumor histology, lesion characteristics, and radiation dose in predicting treatment outcomes.

CONCLUSIONS

This review supports the growing body of evidence that SBRT is an efficacious and safe treatment option for liver metastases. It underscores the need for careful patient selection and personalized treatment planning to optimize outcomes.

The Impact of Ultracentral Tumor Location on Outcomes in Patients with Pulmonary Oligometastases: A Secondary Analysis of the Single-Arm Phase 2 SABR-5 Trial

PURPOSE/OBJECTIVES

There are limited data on outcomes in patients with ultracentral pulmonary oligometastases treated with SABR. The purpose of this study was to determine whether ultracentral location was prognostic for toxicity and survival.

MATERIAL AND METHODS

Oligometastatic lung lesions treated on the single-arm phase 2 SABR-5 trial were retrospectively stratified into 2 cohorts: ultracentral tumors (UC), defined as planning target volume overlap or direct tumor abutment to the proximal bronchial tree, esophagus, great vessels, or heart, and nonultracentral tumors. Cohorts were compared with respect to grade ≥ 2 toxicity, progression-free survival (PFS), and overall survival (OS).

RESULTS

In total, 41 patients with 45 ultracentral metastases and 93 patients with 172 nonultracentral metastases underwent SABR. The most common primary histologies were colorectal (30%), lung (13%), and renal (13%), and these did not differ between groups. Patients with UC had a lower median PFS of 5.8 months compared with 15.8 months in patients with non ultracentral tumors (P < .001). OS was also worse in the UC cohort: median 29.0 months versus not yet reached (P < .001). On multivariable regression, UC remained prognostic for worse PFS (hazard ratio 2.18, P = .004) and OS (hazard ratio 3.45, P < .001). Groups had similar rates of local tumor control. Patients with UC had higher 2-year cumulative incidence of polymetastatic progression: 69.2% versus 31.4% (P < .001). The 2-year cumulative incidence of grade ≥ 2 toxicity was 14.6% for patients with UC and 9.8% for patients with nonultracentral tumors (P = .74). There were no grade 4 or 5 toxicities.

CONCLUSIONS

In this prospective patient cohort, SABR for ultracentral tumor had low toxicity rates and good local control. However, ultracentral location was an adverse prognostic feature for survival. This finding should be validated with larger studies and may be a factor when weighing the benefit versus risk of SABR in patients with pulmonary oligometastases.

Stereotactic Lung Re-Irradiation After a First Course of Stereotactic Radiotherapy with In-Field Relapse: A Valuable Option to Be Considered

BACKGROUND/OBJECTIVES

Stereotactic body radiation therapy (SBRT) has demonstrated high local control rates for inoperable early-stage lung cancers. However, 5-15% of patients experience local relapse within the irradiated volume after treatment, with limited curative salvage options. The aim of this review is to clarify the modalities and outcomes after a second course of SBRT in patients with local relapse after a previous lung SBRT.

METHODS

An exhaustive literature review was conducted to identify, analyse and summarise the results of 21 main studies.

RESULTS

Local repeat lung SBRT after a first course of SBRT showed a favourable local control at 1 and 2 years, ranging from 70 to 90% and 45 to 80%, respectively. Good overall survival rates were also observed at 1 and 2 years reaching up to 95% and 85%, respectively. Toxicity was rare but could be severe, with cases of Grade 4 and 5 toxicities (≈5%). An important dose relationship was observed between re-irradiation dose levels and local control, highlighting the importance of precise dosing. The cumulative doses impacting organs at risk were similarly associated with increased radiation-induced toxicity. Central lung lesions presented a higher risk for severe side effects compared to peripheral ones.

CONCLUSIONS

In conclusion, repeat lung SBRT after a first course of SBRT represents a feasible treatment option in cases of local recurrence. In order to limit severe toxicity, patients must be carefully selected, and particular attention should be given to cumulative doses to organs at risk, as well as tumour location. Thus, further investigations are still needed to refine the optimal parameters for SBRT lung re-irradiation.

Outcomes Analysis of Patients Receiving Local Ablative Therapy for Oligoprogressive Metastatic NSCLC Under First-Line Immunotherapy

CONTEXT

Nonsmall Cell Lung Cancer (NSCLC) treatment relies on first-line immunotherapy as single agent or combined with chemotherapy. Oligoprogression may be observed in this setting.

MATERIAL AND METHOD

We performed a European multicentric retrospective study on patients treated with first-line immunotherapy, who presented with oligoprogressive disease, treated with a local ablative treatment.

RESULTS

A total of 61 patients were retrospectively included between 2018 and 2022. Twenty-four patients (39%) received immunotherapy as single agent, and 37 (61%) chemo-immunotherapy. First oligoprogression occurred more frequently in pre-existing metastatic sites (47% of patients). Median PFS1 (defined as time to first oligoprogression) was 11.5 months [IC95%: 10.0-12.3]. We observed that 37 patients (61%) progressed after first oligoprogression, and 20 (54%) from them presented second oligoprogression. Median OS for the whole cohort was 72.0 months [IC95%: 19.3-124.8], with positive correlation between OS and PFS1 (R=0.65, P < .0001). After loco-ablative treatment with radiotherapy, disease control rate was 89% with ablative radiotherapy: 88% with conventional radiotherapy, and 89% with stereotactic radiotherapy.

CONCLUSION

Patients with oligoprogression under/after immunotherapy have better prognosis with a high risk of subsequent oligoprogression.

Analysis of intra-fractional positioning correction performed by cone beam computed tomography in SBRT treatments

PURPOSE

This study aims to evaluate the positioning correction extracted from Intra-fraction Cone Beam (IF-CBCT) images obtained during Stereotactic Body Radiotherapy (SBRT) treatments, and to assess whether its magnitude justifies its acquisition. In addition, the results obtained in lung, liver, and pancreas SBRTs with two deep inspiration breath-hold systems (DIBH), and for prostate with/without ultrasound (US) monitoring were compared.

METHODS

1449 treatments, performed with two linear accelerators (LINACs) were retrospectively analyzed. DIBH were performed either with a spirometry-based device or a surface-guidance system and one LINAC was equipped with US monitoring system for prostate. Significance tests were used to account for differences between units.

RESULTS

Group systematic error (M) was approximately -0.7 mm for DIBH treatments in superior-inferior (SI) direction with no difference (p > 0.7) between LINACs. Moreover, there was a SI difference of 0.5 mm for prostate treatments (p = 0.008), in favor of the US monitored one. In anterior-posterior (AP) direction, only liver treatments exhibited differences between LINACs, with the spirometer-based system being 0.8 mm inferior (p = 0.003). M<0.4 mm in left-right (LR) direction was found for all locations and LINACs. The spirometer-based system resulted in lower standard deviation of systematic and random errors in most components and locations, with a greater effect observed in liver SBRTs.

CONCLUSIONS

The corrections made with IF-CBCT during SBRT treatments were not negligible. Both DIBH systems were effective in managing respiratory movements. However, the spirometry-based system was slightly more accurate. In addition, US monitoring of the prostate appeared to be useful in reducing target shift.

Stereotactic body radiotherapy takes on Lung Oligometastases: Latest breakthroughs

Lung oligometastases represent an intermediate state of cancer dissemination between localized and widespread metastases. Stereotactic body radiation therapy (SBRT) has emerged as an effective treatment option, with an efficacy comparable to that of surgical resection. This review aimed to provide a comprehensive summary of the latest advancements and controversial issues regarding SBRT for lung oligometastases. It focuses on four crucial perspectives: efficacy of SBRT, optimal patient selection criteria, technological innovations, and synergistic effects of SBRT combined with systemic therapy. Relevant clinical trials investigating SBRT for lung oligometastases have been conducted, with median 1- and 5-year local control rates of 90% and 79%, respectively. The origin of the primary tumor, size and number of lesions, and biomarker profiles were highlighted as pivotal considerations in patient selection. The precise dose delivery was enhanced using robotic SBRT and optimized dose fractionation schemes. Evidence suggests that dose escalation above 100 Gy biologically effective dose may improve tumor control. Combined immunotherapy and SBRT have demonstrated synergistic effects in prolonging progression-free survival and overall survival. This review provides valuable insights into the precise treatment of oligometastatic lung diseases using SBRT. Further multicenter randomized trials are warranted to develop definitive patient selection criteria and optimize the integration with systemic therapies.

Stereotactic body radiotherapy of central lung tumours using a 1.5 T MR-linac: First clinical experiences

Background

MRI-guidance may aid better discrimination between Organs at Risk (OARs) and target volumes in proximity of the mediastinum. We report the first clinical experiences with Stereotactic Body Radiotherapy (SBRT) of (ultra)central lung tumours on a 1.5 T MR-linac.

Materials and Methods

Patients with an (ultra)central lung tumour were selected for MR-linac based SBRT treatment. A T2-weighted 3D sequence MRI acquired during free breathing was used for daily plan adaption. Prior to each fraction, contours of Internal Target Volume (ITV) and OARs were deformably propagated and amended by a radiation oncologist. Inter-fractional changes in volumes and coverage of target volumes as well as doses in OARs were evaluated in offline and online treatment plans.

Results

Ten patients were treated and completed 60 Gy in 8 or 12 fractions. In total 104 fractions were delivered. The median time in the treatment room was 41 min with a median beam-on time of 8.9 min. No grade ≥3 acute toxicity was observed. In two patients, the ITV significantly decreased during treatment (58 % and 37 %, respectively) due to tumour shrinkage. In the other patients, 81 % of online ITVs were within ±15 % of the volume of fraction 1. Comparison with the pre-treatment plan showed that ITV coverage of the online plan was similar in 52 % and improved in 34 % of cases. Adaptation to meet OAR constraints, led to decreased ITV coverage in 14 %.

Conclusions

We describe the workflow for MR-guided Radiotherapy and the feasibility of using 1.5 T MR-linac for SBRT of (ultra) central lung tumours.