Stereotactic body radiation therapy for isolated hilar and mediastinal non-small cell lung cancers

Prospective phase II trial on ablative stereotactic body radiation therapy (SBRT) for medically inoperable thoracic nodes metastases

BACKGROUND

Oligometastases in mediastinal nodes are increasingly prevalent, posing challenges for treatment with stereotactic body radiotherapy (SBRT) due to proximity to organs at risk (OARs). We report the results of a single prospective observational phase II trial on ablative SBRT for medically inoperable thoracic nodes metastases (NCT02970955).

MATERIAL AND METHODS

Since 2017, patients with < 3 nodal metastases were evaluated by the tumor board and included if deemed inoperable. SBRT was delivered using risk adaptive approach based on number, site and size of metastatic nodes (50 Gy/5fractions, 60 Gy/8fractions, 70 Gy/10 fractions). Planning target volume (PTV) partial underdosage was allowed. The primary end point was local control (LC) at 12 months. Secondary end points were: acute and late toxicities, overall survival (OS), progression free survival (PFS), and time to next systemic therapy (TTNS).

RESULTS

Between 03/2017-11/2021, 32 patients (41 nodal metastases) were included. NSCLC (13pts), breast (5pts) and colorectal cancer (4pts) were the most represented primary tumour. In 66 % cases, partial PTV undercoverage was necessary. LC at 1 and 2 years was 93.5 % and 82.3 %, respectively. Treatment was well-tolerated with no acute or late toxicity ≥ G3. Median OS was 59.7 months. OS at 1 and 2 years was 96.9 % and 83.8 % respectively. Median PFS was 12.2 months. PFS at 1 and 2 years was 53.1 % and 31.3 %, respectively.

CONCLUSION

This trial supported the feasibility and safety of ablative SBRT for thoracic nodes metastases thanks to risk adaptive approach allowing to delay of new systemic therapies. Larger studies are needed to confirm these observations.

Widening the therapeutic window for central and ultra-central thoracic oligometastatic disease with stereotactic MR-guided adaptive radiation therapy (SMART)

BACKGROUND/PURPOSE

Central/ultra-central thoracic tumors are challenging to treat with stereotactic radiotherapy due potential high-grade toxicity. Stereotactic MR-guided adaptive radiation therapy (SMART) may improve the therapeutic window through motion control with breath-hold gating and real-time MR-imaging as well as the option for daily online adaptive replanning to account for changes in target and/or organ-at-risk (OAR) location.

MATERIALS/METHODS

26 central (19 ultra-central) thoracic oligoprogressive/oligometastatic tumors treated with isotoxic (OAR constraints-driven) 5-fraction SMART (median 50 Gy, range 35-60) between 10/2019-10/2022 were reviewed. Central tumor was defined as tumor within or touching 2 cm around proximal tracheobronchial tree (PBT) or adjacent to mediastinal/pericardial pleura. Ultra-central was defined as tumor abutting the PBT, esophagus, or great vessel. Hard OAR constraints observed were ≤ 0.03 cc for PBT V40, great vessel V52.5, and esophagus V35. Local failure was defined as tumor progression/recurrence within the planning target volume.

RESULTS

Tumor abutted the PBT in 31 %, esophagus in 31 %, great vessel in 65 %, and heart in 42 % of cases. 96 % of fractions were treated with reoptimized plan, necessary to meet OAR constraints (80 %) and/or target coverage (20 %). Median follow-up was 19 months (27 months among surviving patients). Local control (LC) was 96 % at 1-year and 90 % at 2-years (total 2/26 local failure). 23 % had G2 acute toxicities (esophagitis, dysphagia, anorexia, nausea) and one (4 %) had G3 acute radiation dermatitis. There were no G4-5 acute toxicities. There was no symptomatic pneumonitis and no G2 + late toxicities.

CONCLUSION

Isotoxic 5-fraction SMART resulted in high rates of LC and minimal toxicity. This approach may widen the therapeutic window for high-risk oligoprogressive/oligometastatic thoracic tumors.

Stereotactic body radiation therapy for the treatment of lymph node metastases: a retrospective mono-institutional study in a large cohort of patients

Introduction

Lymph node metastases (NMs) are a common site of tumor spread that can occur at different times of the disease. Stereotactic body radiation therapy (SBRT) can be a therapeutic option for the treatment of NMs in the setting of oligometastatic disease (OMD). The aim of this study was to evaluate as primary end points the local control (LC) and secondary end points the locoregional nodal control (LRNC), distant nodal control (DNC), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS), and concurrently to assess the predictive factors of response.

Methods

This is a retrospective study that analyzes a group of patients treated with SBRT on NMs from different primary tumors, with a of maximum five metastasis. Treated lesions were divided into four groups: oligometastatics, oligorecurrents, oligoprogressives, and oligopersistents.

Results

From 2007 to 2021, 229 NMs were treated in 174 patients with different primary tumor. The schedule most represented was 30 Gy in five fractions. The LC was obtained in 90% of NMs treated by SBRT with rates at 1, 3, and 5 years of 93%, 86%, and 86%, respectively. The LRNC was reached in 84% of cases with rates at 1, 3, and 5 years of 88%, 83%, and 77%, respectively. The DNC was obtained in 87% of cases with rates at 1, 3, and 5 years of 92%, 82%, and 78%, respectively. The DMFS was obtained in 38% of cases with rates at 1, 3, and 5 years of 57%, 40%, and 30%, respectively. The rate of PFS were 44%, 23%, and 13% at 1, 3, and 5 years, respectively. The rates at 1, 3, and 5 years of OS were 78%, 48%, and 36%, respectively.

Conclusion

SBRT is an option for the treatment of NMS, with high rates of LC, improving survival, and with a good safety and tolerance. Tumor volume, tumor burden, lesion site, and doses can be predictive factors of response; however, multi-institutional studies with a greater number of patients could be helpful to better select patients and understand the right integrations between ablative treatment and systemic therapies.

Ten fraction hypofractionated stereotactic body radiotherapy for the management of ultracentral lung tumors: a retrospective analysis of dosimetry, outcomes, and toxicity

BACKGROUND

The management of ultracentral thoracic tumors with ablative dose of radiotherapy remains challenging given proximity to critical central structures. We report patient outcomes, toxicity, and dosimetry for ultracentrally located tumors with hypofractionated stereotactic body radiotherapy (hfSBRT).

METHODS

Seventy-eight individuals (50 initial radiotherapy, 28 re-irradiation) undergoing 10 fraction hfSBRT for ultracentrally located thoracic tumors treated between 2009 and 2020 at a single institution were retrospectively reviewed. Overall survival (OS), progression free survival (PFS), and local control (LC) were calculated. Incidence and grade of treatment related toxicity were evaluated. Dosimetric analysis of treatment plans and critical adjacent OARs was performed.

RESULTS

At a median follow up time of 13 months, 1- and 3-year OS, PFS, and LC were 89%/63%, 37%/18%, and 84%/65%, respectively. Median dose was 65 Gy (BED10 = 107.25 Gy). Median primary bronchial tree maximum dose (Dmax) was 60 Gy (V50 = 0.96 cc). Median esophageal Dmax was 38 Gy (V40 = 0 cc). Median great vessel Dmax was 68 Gy (V50 = 3.53 cc). The most common ≥ grade 2 adverse event was pneumonitis, in 15 individuals (20%). Grade 3 or higher toxicity was observed in 9 individuals (12%): three cases of grade 3 pneumonitis (two re-irradiation, one initial radiotherapy), one grade 3 esophageal stricture following re-irradiation, two grade 3 endobronchial obstructions both following initial radiotherapy, and three grade 5 hemoptysis events (two re-irradiation, one initial radiotherapy). One hemoptysis event was categorized as "possibly" related to treatment, while the remaining two events were categorized as "unlikely" related to treatment in patients with clear evidence of disease progression.

CONCLUSIONS

hfSBRT to ultracentral lung tumors delivered over 10 fractions is a safe and effective treatment option, with acceptable rates of toxicity and good rates of tumor control.

TRIAL REGISTRATION

IRB registration number 12573.

Stereotactic body radiotherapy for mediastinal lymph node with CyberKnife®: Efficacy and toxicity

PUPRPOSE

Stereotactic body radiotherapy is more and more used for treatment of oligometastatic mediastinal lymph nodes. The objective of this single-centre study was to evaluate its efficacy in patients with either a locoregional recurrence of a pulmonary or oesophageal cancer or with distant metastases of extrathoracic tumours.

PATIENTS AND METHODS

Patients with oligometastatic mediastinal lymph nodes treated with CyberKnife from June 2010 to September 2020 were screened. The primary endpoint was to assess local progression free survival and induced toxicity. Secondary endpoints were overall survival and progression free survival. The delay before introduction of systemic treatment in the subgroup of patients who did not receive systemic therapy for previous progression was also evaluated.

RESULTS

Fifty patients were included: 15 with a locoregional progression of a thoracic primary tumour (87% pulmonary) and 35 with mediastinal metastasis of especially renal tumour (29%). Median follow-up was 27 months (6-110 months). Local progression free survival at 6, 12 and 18 months was respectively 94, 88 and 72%. The rate of local progression was significantly lower in patients who received 36Gy in six fractions (66% of the cohort) versus other treatment schemes. Two grade 1 acute oesophagitis and one late grade 2 pulmonary fibrosis were described. Overall survival at 12, 18 and 24 months was respectively 94, 85 and 82%. Median progression free survival was 13 months. Twenty-one patients were treated by stereotactic body irradiation alone without previous history of systemic treatment. Among this subgroup, 11 patients (52%) received a systemic treatment following stereotactic body radiotherapy with a median introduction time of 17 months (5-52 months) and 24% did not progress.

CONCLUSION

Stereotactic body irradiation as treatment of oligometastatic mediastinal lymph nodes is a well-tolerated targeted irradiation that leads to a high control rate and delay the introduction of systemic therapy in selected patients.

Stereotactic Body Radiation Therapy (SBRT) for Oligorecurrent/Oligoprogressive Mediastinal and Hilar Lymph Node Metastasis: A Systematic Review

Simple Summary

This paper is a review of the literature on oligorecurrent/oligoprogressive mediastinal and hilar lymph node metastasis treated with SBRT. The use of mediastinal SBRT had historically been not feasible in view of the expected toxicity due to the proximity of critical structures such as the airways and esophagus. Despite the heterogeneity and lack of some data in the studies analyzed, this literature review is the first published and can be a valid guide for the radiotherapist in the management of oligometastatic/oligoprogressive patients, with particular regard to the radiotherapy doses, dose constraints for organs at risk, and clinical outcomes.

Abstract

Introduction: Mediastinal or hilar lymph node metastases are a challenging condition in patients affected by solid tumors. Stereotactic body radiation therapy (SBRT) could play a crucial role in the therapeutic management and in the so-called “no-fly zone”, delivering high doses of radiation in relatively few treatment fractions with excellent sparing of healthy surrounding tissues and low toxicity. The aim of this systematic review is to evaluate the feasibility and tolerability of SBRT in the treatment of mediastinal and hilar lesions with particular regard to the radiotherapy doses, dose constraints for organs at risk, and clinical outcomes. Materials and methods: Two blinded investigators performed a critical review of the Medline, Web of Knowledge, Google Scholar, Scopus, and Cochrane databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA), starting from a specific question: What is the clinical impact of SBRT for the treatment of oligorecurrent/oligoprogressive mediastinal and hilar metastasis? All retrospective and prospective clinical trials published in English up to February 2022 were analyzed. Results: A total of 552 articles were identified and 12 of them were selected with a total number of 478 patients treated with SBRT for mediastinal or hilar node recurrence. All the studies are retrospective, published between 2015 and 2021 with a median follow-up ranging from 12 to 42.2 months. Studies following SBRT for lung lesions or retreatments after thorax radiotherapy for stage III lung cancer were also included. The studies showed extensive heterogeneity in terms of patient and treatment characteristics. Non-small cell lung cancer was the most frequently reported histology. Different dose schemes were used, with a higher prevalence of 4–8 Gy in 5 or 6 fractions, but dose escalation was also used up to 52 Gy in 4 fractions with dose constraints mainly derived from RTOG 0813 trial. The radiotherapy technique most frequently used was volumetric modulated arc therapy (VMAT) with a median PTV volume ranging from 7 to 25.7 cc. The clinical outcome seems to be very encouraging with 1-year local control (LC), overall survival (OS) and progression-free survival (PFS) rates ranging from 84 to 94%, 53 to 88% and 23 to 53.9%, respectively. Half of the studies did not report toxicity greater than G3 and only five cases of fatal toxicity were reported. CONCLUSIONS: From the present review, it is not possible to draw definitive conclusions because of the heterogeneity of the studies analyzed. However, SBRT appears to be a safe and effective option in the treatment of mediastinal and hilar lymph node recurrence, with a good toxicity profile. Its use in clinical practice is still limited, and there is extensive heterogeneity in patient selection and fractionation schedules. Good performance status, small PTV volume, absence of previous thoracic irradiation, and administration of a high biologically effective dose (BED) seem to be factors that correlate with greater local control and better survival rates. In the presence of symptoms related to the thoracic lymph nodes, SBRT determines a rapid control that lasts over time. We look forward to the prospective studies that are underway for definitive conclusions.

Thoracic Radiotherapy for Renal Cell Carcinoma Metastases: Local Control for the Management of Lung and Mediastinal Disease in the Modern Era

INTRODUCTION/BACKGROUND

Radiotherapy (RT) is an alternative local therapy to metastasectomy in the treatment of thoracic metastases from renal cell carcinoma (RCC), including the management of life-threatening disease.

PATIENTS AND METHODS

We reviewed patients with lung and mediastinal RCC metastases treated with RT at our institution. Overall survival (OS) and metastasis control (MC) was measured from the start of RT using the Kaplan-Meier (KM) method.

RESULTS

Seventy-one patients were treated with RT for 89 lung (n = 58) or mediastinal (n = 31) metastases. Of 89 treated lesions, 11 (12%) had local tumor recurrence, at a median of 1.6 years (range 0.4-2.9). MC at 1, 3, and 5-years was 96.6%, 83.5%, and 67.9%, respectively. For the 58-lung metastasis-directed RT courses, MC rates at 1, 3, and 5-years were 95.0%, 84.5%, and 84.5%, respectively (median MC not reached). For the 31-mediastinum metastasis-directed RT courses, MC rates at 1, 3, and 5-years were 100%, 43.4%, and 43.4%, respectively (median MC 2.9 years). MC was significantly improved for lung lesions compared to mediastinal lesions (P = .046). OS for the entire cohort at 1, 3, and 5 years was 65.2%, 48.5%, and 38.0%. There was no difference in OS based on metastatic sites in the 71 patients. Nineteen patients received RT to 19 lesions with the intention of preventing an event such as airway compromise or vascular invasion. One and two-year MC for these 19 lesions were 88.9% and 71.1%, respectively (median local control 2.4 years). OS in these 19 patients at 1, 2, and 5 years were 62.1%, 48.3%, and 32.2% respectively, with median survival 1.2 years. No patients developed grade 4 or 5 acute or late toxicities.

CONCLUSION

Radiation therapy can safely achieve high metastasis control rates for lung and mediastinal metastases from RCC, including lesions at high risk for causing a life-threatening event.

Exceeding Radiation Dose to Volume Parameters for the Proximal Airways with Stereotactic Body Radiation Therapy Is More Likely for Ultracentral Lung Tumors and Associated with Worse Outcome

Simple Summary

The optimal way to treat central (CLT) and ultracentral (UCLT) lung tumors with curative radiation is unclear. We evaluated 83 patients with CLT and UCLT who underwent a curative radiotherapy technique called stereotactic body radiation therapy (SBRT). On statistical analysis, patients with UCLT had worse overall survival. Using a cohort of patients matched for relevant variables such as gender and performance status, we evaluated radiation doses to critical central structures such as the airway and heart. In this group, patients with UCLT were more likely to exceed dose constraints as compared CLT, particularly constraints regarding the airway. Additionally, patients had worse non-cancer associated survival when radiation doses were higher than 18 Gy to 4cc’s of either the trachea or proximal bronchial tree. Based on these findings, patients with UCLT have worse outcomes which could be secondary to higher radiation doses to the trachea and proximal bronchial tree.

Abstract

The preferred radiotherapeutic approach for central (CLT) and ultracentral (UCLT) lung tumors is unclear. We assessed the toxicity and outcomes of patients with CLT and UCLT who underwent definitive five-fraction stereotactic body radiation therapy (SBRT). We reviewed the charts of patients with either CLT or UCLT managed with SBRT from June 2010–April 2019. CLT were defined as gross tumor volume (GTV) within 2 cm of either the proximal bronchial tree, trachea, mediastinum, aorta, or spinal cord. UCLT were defined as GTV abutting any of these structures. Propensity score matching was performed for gender, performance status, and history of prior lung cancer. Within this cohort of 83 patients, 43 (51.8%) patients had UCLT. The median patient age was 73.1 years with a median follow up of 29.9 months. The two most common dose fractionation schemes were 5000 cGy (44.6%) and 5500 cGy (42.2%) in five fractions. Multivariate analysis revealed UCLT to be associated with worse overall survival (OS) (HR = 1.9, p = 0.02) but not time to progression (TTP). Using propensity score match pairing, UCLT correlated with reduced non-cancer associated survival (p = 0.049) and OS (p = 0.03), but not TTP. Within the matched cohort, dosimetric study found exceeding a D4cc of 18 Gy to either the proximal bronchus (HR = 3.9, p = 0.007) or trachea (HR = 4.0, p = 0.02) was correlated with worse non-cancer associated survival. In patients undergoing five fraction SBRT, UCLT location was associated with worse non-cancer associated survival and OS, which could be secondary to excessive D4cc dose to the proximal airways.

Salvage Photon or Proton Radiotherapy for Oligo-recurrence in Regional Lymph Nodes After Surgery for Non-small Cell Lung Cancer

BACKGROUND/AIM

To evaluate the outcome of definitive salvage radiotherapy (RT) in non-small cell lung cancer (NSCLC) patients with oligo-recurrence in regional lymph nodes after surgery.

PATIENTS AND METHODS

Between January 2003 and December 2016, 33 patients with NSCLC were reviewed from radiotherapy database at our hospital. All patients received photon or proton salvage RT for metastases in the regional lymph nodes.

RESULTS

The median follow-up from salvage RT was 35.2 (range=5.9-89.6) months. Recurrences occurred in 18 (55%) patients, and the 3-year overall and progression-free survival rates were 63.8% and 45.1%, respectively. Regional and local control improved patients' survival and these control rates were increased by use of concurrent chemotherapy (p=0.039) and proton RT (p=0.084). No grade 4 acute or late non-hematologic toxicities were observed.

CONCLUSION

Salvage RT is an effective treatment for NSCLC patients with oligo-recurrence at regional lymph nodes.

Outcomes with multi-disciplinary management of central lung tumors with CT-guided percutaneous high dose rate brachyablation

BACKGROUND

Centrally located lung tumors present treatment challenges given their proximity to mediastinal structures including the central airway, esophagus, major vessels, and heart. Therapeutic options can be limited for medically inoperable patients, particularly if they have received previous thoracic radiotherapy. High dose rate (HDR) brachyablation was developed to improve the therapeutic ratio for patients with central lung tumors. The purpose of this study is to report initial safety and efficacy outcomes with this treatment for central lung malignancies.

METHODS

From September 2015 to August 2019, a total of 25 patients with 37 pulmonary tumors were treated with percutaneous HDR brachyablation. Treatment was delivered by a multi-disciplinary team of interventional radiologists, pulmonologists, and radiation oncologists. Twenty-three patients received a median dose of 21.5 Gy (range 15-27.5) in a single fraction, whereas two patients received median dose of 24.75 Gy (range 24-25.5) over 2-3 fractions. Tumor local control (LC) was evaluated by Response Evaluation Criteria in Solid Tumors v1.1. Treatment-related toxicities were graded by Common Terminology Criteria for Adverse Events v5.0, with adverse events less than 90 days defined as acute, and those occurring later were defined as late. LC, progression-free survival (PFS), and overall survival (OS) rates were estimated by the Kaplan-Meier method.

RESULTS

Of 37 treated tumors, 88% were metastatic. Tumor location was central and ultra-central in 24.3% and 54.1%, respectively. Average tumor volume was 11.6 cm³ (SD 12.4, range 0.57-62.8). Median follow-up was 19 months (range 3-48). Two-year LC, PFS, and OS were 96.2%, 29.7%, and 65.5%, respectively. Thirteen of 39 (33.3%) catheter implantation procedures were associated with trace minor pneumothorax requiring no intervention, 1 (2.5%) procedure with minor radiographic pulmonary hemorrhage, and 4 (10.3%) with major pneumothorax requiring chest tube insertions. All procedural complications resolved within 24 h from treatment. Acute grade 1-2 toxicity was identified in 4 patients, whereas none developed late toxicity beyond 90 days of follow-up.

CONCLUSION

Percutaneous HDR brachyablation is a safe and promising treatment option for centrally located primary and metastatic lung tumors. Future comparisons with stereotactic body radiotherapy and other ablative techniques are warranted to expand multi-disciplinary management options.

Developments in radiation techniques for thoracic malignancies

Radiation therapy is a cornerstone of modern lung cancer treatment alongside surgery, chemotherapy, immunotherapy and targeted therapies. Advances in radiotherapy techniques have enhanced the accuracy of radiation delivery, which has contributed to the evolution of radiation therapy into a guideline-recommended treatment in both early-stage and locally advanced nonsmall cell lung cancer. Furthermore, although radiotherapy has long been used for palliation of disease in advanced lung cancer, it is increasingly having a role as a locally ablative treatment in patients with oligometastatic disease.This review provides an overview of recent developments in radiation techniques, particularly for non-radiation oncologists who are involved in the care of lung cancer patients. Technical advances are discussed, and findings of recent clinical trials are highlighted, all of which have led to a changing perception of the role of radiation therapy in multidisciplinary care.

Stereotactic Radiation for Lung Cancer: A Practical Approach to Challenging Scenarios

Stereotactic body radiation therapy (SBRT) is an effective and well-tolerated treatment for medically inoperable patients with early stage NSCLC. SBRT is a noninvasive treatment involving the delivery of ablative radiation doses with high precision in the course of a few treatments. Relative to conventionally fractionated radiation, SBRT achieves superior local control and survival. SBRT use has increased dramatically in the past 15 years and is currently considered the standard of care in cases of inoperable early stage NSCLC. It is being increasingly applied to more complex patient populations at higher risk of treatment-related toxicity. In these more complex patients, there is an increasing need to balance patient and treatment factors in selecting the optimal patients for SBRT. Here, we review several challenging clinical scenarios often encountered in thoracic multidisciplinary tumor boards.

The HILUS-Trial-a Prospective Nordic Multicenter Phase 2 Study of Ultracentral Lung Tumors Treated With Stereotactic Body Radiotherapy

INTRODUCTION

Stereotactic body radiation therapy of thoracic tumors close to the central airways implies risk of severe toxicity. We report a prospective multicenter phase 2 trial for tumors located less than or equal to 1 cm from the proximal bronchial tree with primary end point of local control and secondary end point of toxicity.

METHODS

Stereotactic body radiation therapy with 7 Gy × 8 was prescribed to the 67% isodose encompassing the planning target volume. The patients were stratified to group A (tumors ≤ 1 cm from the main bronchi and trachea) or group B (all other tumors). Risk factors for treatment-related death were tested in univariate analysis, and a logistic regression model was developed for fatal bronchopulmonary bleeding versus dose to the main bronchi and trachea.

RESULTS

A total of 65 patients (group A/group B, n = 39/26) were evaluated. The median distance between the tumor and the proximal bronchial tree was 0 mm (0-10 mm). The 2-year local control was 83%. Grade 3 to 5 toxicity was noted in 22 patients, including 10 cases of treatment-related death (bronchopulmonary hemorrhage, n = 8; pneumonitis, n = 1; fistula, n = 1). Dose to the combined structure main bronchi and trachea and tumor distance to the main bronchi were important risk factors. Dose modeling revealed minimum dose to the "hottest" 0.2 cc to the structure main bronchi and trachea as the strongest predictor for lethal bronchopulmonary hemorrhage.

CONCLUSIONS

On the basis of the presented data, 7 Gy × 8, prescribed to the planning target volume-encompassing isodose, should not be used for tumors located within 1 cm from the main bronchi and trachea. Group B-type tumors may be considered for the treatment on the basis of an individual risk-benefit assessment and a maximum dose to the main bronchi and trachea in the order of 70 to 80 Gy (equivalent dose in 2 Gy fractions).

A single institutional experience with central lung stereotactic body radiation therapy demonstrating encouraging results with increased inter-fraction time

Background

Stereotactic body radiation therapy (SBRT) is an effective treatment modality for non-small cell lung cancer (NSCLC); however, there are concerns regarding potential toxicity for centrally located tumors.

Methods

This retrospective study considered patients with SBRT for central lung NSCLC (defined as a tumor within 2 cm of any mediastinal critical structure). The institutional protocol was that patients with central tumors received SBRT less frequently than daily—generally once or twice weekly.

Results

A total of 115 patients with 148 lesions were treated with SBRT to a median 45 [5–60] Gy in 4 [1–5] fractions over a median 5.3 [0–18] days. Many patients treated with this method presented with advanced disease: 58 treatments involved nodal targets, and 42 had stage 3 disease. 52% of patients had chronic obstructive pulmonary disease (COPD), and only 49% had a biopsy, often due to concerns regarding other medical comorbidities. Rates of prior chemotherapy, thoracic surgery, and thoracic radiotherapy were 32%, 21%, and 49%, respectively. Via the Kaplan-Meier method, 2-year overall survival was 65%, and 2-year local control was 77%. Two-year local-progression free survival was 53%, and 2-year progression-survival was 48%. Treatments for stage 3 disease had an impressive 82% 2-year local control that was comparable to early stage treatments. Patients with stage 3 disease had a 2-year overall survival of 59%, which trended towards decreased overall survival compared to early stage patients. There were 13 grade 1 (9%) and 14 grade 2 (9%) toxicities. There were no reported grade ≥3 acute or late toxicities and only 3 cases of pneumonitis.

Conclusions

Our series demonstrates encouraging local control with low rates of toxicity for central lung SBRT, including many stage 3 patients. This may be the result of the relatively large inter-fraction interval. This interval may allow for greater tumor effects (such as reoxygenation) and improved tolerance from normal tissues.

Systematic review of stereotactic body radiotherapy for nodal metastases

The aim of this analysis was to assess the efficacy of stereotactic body radiotherapy (SBRT) in terms of local control (LC) and progression-free survival (PFS) in patients with lymph node metastases (NMs) from solid tumors. A systematic literature search from the earliest date to July 25th, 2019 was performed following PRISMA guidelines. Papers reporting LC and/or PFS of NMs using SBRT (< 10 fractions) were selected. The clinical outcomes rates were pooled by means of a random or fixed-effect model. Twenty-nine studies were eligible (969 patients: 938 (LC) and 698 (PFS)). LC and PFS results were reported in 28 and 18 papers, respectively. Heterogeneity was observed in terms of patient and treatment characteristics. Pooled 2-year LC reported in 11 studies was 79.3% (95%CI, 72.8%-85.7%) with substantial heterogeneity between studies (Q2 test: p = 0.0083; I2 = 57.9%), while pooled 2-year PFS reported in 8 studies was 35.9% (95%CI, 22.1%-49.7%) with very high heterogeneity between studies (Q2 test: p < 0.0001; I2 = 86.1%). Grade ≥ 3 and Grade 5 toxicity rates were 2.0% and 0.2%, respectively. SBRT of NMs seems to be safe and effective in terms of LC. However, due to the marked heterogeneity of the included series, prospective studies are required.

Stereotactic body radiotherapy (SBRT) for central and ultracentral node-negative lung tumors

Advancements in imaging and radiotherapy (RT) techniques have allowed for remarkably precise delivery of high radiation dose per treatment fraction to intrathoracic targets. As a non-invasive therapeutic modality (compared to surgery), stereotactic body radiotherapy (SBRT) is an attractive option for patients with early-stage non-small cell lung cancers and oligometastases, especially for older patients with significant comorbidities and pre-existing pulmonary dysfunction. However, the outcomes and side effect profile of SBRT are highly dependent on tumor location, especially if the tumor is located centrally (within 2 cm of the proximal bronchial tree (PBT)] or ultracentrally (touching or within 1 cm of the mediastinum, esophagus, and PBT). In this focused review, we will examine the contemporary practice and principles of using hypofractionated RT or SBRT for central and ultracentral thoracic tumors. We will identify future directions on how this practice may be incorporated into the increasingly complicated modern paradigm of lung cancer treatments which now include immunotherapy along with proton beam radiotherapy.

Stereotactic Body Radiation Therapy for Mediastinal and Hilar Lymph Node Metastases

PURPOSE

Stereotactic body radiation therapy (SBRT) to metastatic mediastinal and hilar lymphadenopathy (MHL) is challenging owing to the proximity of centrally located organs-at-risk. As limited data exist on the safety and efficacy of SBRT for MHL, a retrospective review of clinical outcomes was conducted from a large academic center.

METHODS AND MATERIALS

Eligible patients received SBRT to MHL between 2014 to 2019 for the following indications: oligometastases, oligoprogression, or local control of a dominant area of progression. The primary endpoint was grade ≥3 toxicity (Common Terminology Criteria for Adverse Events, version 5.0). The cumulative incidence function evaluated local failure (LF) and starting or changing systemic therapy (SCST). Kaplan-Meier methodology estimated progression-free survival (PFS) and overall survival (OS).

RESULTS

Fifty-two patients (84 metastases) were included. Median follow-up was 20 months. Primary cancer sites included kidney (53.8%), lung (13.4%), breast (7.7%), and other (25.1%). Indications for SBRT were oligoprogression (n = 35; 67.3%), oligometastases (n = 10; 19.2%), or local failure of a dominant area of progression (n = 7; 13.5%). The majority (n = 31; 59.6%) received SBRT to a single lymph node metastasis. Median SBRT dose was 35 Gy (range, 30-50 Gy) with a median biologically effective dose of 59.5 Gy (range, 48-100 Gy). All treatments were in 5 fractions. Seven grade ≥3 toxicities were experienced by 6 patients (11.5%) and were mostly transient (5/7; 71%). There was a single (1.9%) grade 5 toxicity (radiation pneumonitis). The cumulative incidence of LF was 9.0% at 2 years. The cumulative incidence of SCST was 33.2% and 57.1% at 1 and 2 years, respectively. Median PFS was 4.0 months (95% confidence interval, 2.8-7.3) and median OS was 31.7 months (95% confidence interval, 23.8-87.5).

CONCLUSIONS

In one of the largest single institutional series of SBRT for MHL, moderate rates of grade ≥3 toxicity were observed, although the majority were transient. This treatment resulted in low LF rates and potentially delayed SCST for many patients.

Nodal recurrences after stereotactic body radiotherapy for early stage non-small-cell lung cancer

Lobectomy is considered the standard of care for early stage non-small-cell lung cancer. However, for those patients who remain unfit to undergo surgery due to advanced age, poor performance status, comorbidities, poor pulmonary reserve or a combination of these are now treated with stereotactic body radiation therapy (SBRT). Due to its noninvasive nature, lower cost, lower toxicity, reduced recovery time and equivalent efficacy, even medically operable patients are attracted to the option of SBRT despite the lack of level I evidence. Thus, studying the incidence and patterns of recurrence after SBRT help in understanding the magnitude of the problem, risk factors associated with the different patterns of recurrence, and aid in devising strategies to prevent them in future. Nodal recurrences are not uncommon after SBRT and can potentially lead to further seeding for distant metastases and ultimately poor survival. This review is aimed at reviewing the published data on the incidence of nodal recurrences after SBRT and compare it to surgery, identify potential risk factors for recurrence, salvage treatment options and prevention strategies.

Stereobody radiotherapy for nodal recurrences in oligometastatic patients: a pooled analysis from two phase I clinical trials

Stereotactic body radiotherapy (SBRT) has been shown to achieve high local control rates in limited metastatic burden of disease. Few papers reported on the efficacy of SBRT in nodal oligometastases. The primary aim of the present paper was to analyze the treatment outcome in this setting. Data from DESTROY-1 and SRS-DESTROY-2 phase I clinical trials were reviewed and analyzed. These trials were based on a 5 fractions and a single fraction regimens, respectively. End-points of this analysis were toxicity rates, overall response rate (ORR), and local control (LC). Patients treated between December 2003 and January 2018, with any metastatic site, and primary tumor type and histology were included. One hundred-eighty-one patients (M/F: 93/88; median age: 67, range 37-88) treated with SBRT on 253 nodal lesions were analyzed. Initially, the used technique was 3D-CRT (20.9%), while subsequently treatments were delivered by VMAT (79.1%). The total dose to the PTV ranged between 12 Gy/single fraction to 50 Gy/5 fractions. With a median follow-up of 21 months (2-124), no grade 3 acute or late toxicity was recorded. ORR based on functional imaging was 92.5% with a complete response rate of 76%. Two- and three-year actuarial LC were 81.6% and 76.0%, respectively. Our large pooled analysis confirms the efficacy and safety of SBRT/SRS in patients with nodal metastases and identifies clinical and treatment variables able to predict complete response and local control rate.

Low-dose hilar and mediastinal stereotactic body radiation therapy for non-small cell lung cancer: Analysis of outcomes in patients receiving one or multiple courses of treatment

Background

This study reports the outcomes of a single institutional experience treating non‐small cell lung cancer (NSCLC) involving the pulmonary hilum with low‐dose stereotactic body radiation therapy (SBRT). The authors also present a series of repeat hilar SBRT.

Methods

Inclusion criteria required treatment with SBRT for NSCLC involving regional lymph nodes of the: (i) hilum, (ii) mediastinum, (iii) aortopulmonary window (station 5), or (iv) mainstem bronchus. At least one clinical follow‐up with imaging was required, unless the patient had a prior documented death from cancer.

Results

A total of 32 patients with 44 treatments were included, and 37 treatments targeted the hilum directly, with seven concerning the mediastinum, AP window, or mainstem bronchus. Median dose was 28 Gy in four fractions with once‐weekly fractionation. At a median clinical follow‐up of 23 months, local control was 64%. Median overall survival was 24 months, and median progression‐free survival was 15 months. A total of 48% of treatments resulted in complete radiographic response on last imaging follow‐up, and no cases of grade ≥ 3 toxicity were reported. For repeat SBRT (after prior hilar SBRT), local control was 92%. Median overall survival was 20 months, and median progression‐free survival was 19 months. Complete radiographic response was noted after 58% of treatments, with 0 instances of progressive response and no reported side effects.

Conclusions

Low‐dose hilar SBRT was efficacious and well‐tolerated, with impressive overall survival and no grade ≥ 3 toxicity. Repeat treatments with SBRT were feasible and effective, demonstrating overall survival, local control, and toxicity comparable to primary treatments.

Key points

Optimized CyberKnife Lung Treatment: Effect of Fractionated Tracking Volume Change on Tracking Results

Objectives

To explore the impact of volume change in the fractionated tracking of stereotactic radiotherapy on the results of synchronous, respiratory tracking algorithm using CyberKnife.

Methods

A total of 38 lung tumor patients receiving stereotactic radiotherapy at our center from March 2018 to October 2019 were counted. Photoshop CS4 image processing software was used to obtain the pixels and the average value of brightness of the tracking volume in the image and calculate the grayscale within the contour of the tracking volume on the real-time X-ray image. At the same time, parameters of the synchronous respiratory tracking algorithm of the fractional CyberKnife were extracted for comparison between the volume of image-guided image tracking and the number of fractions during stereotactic radiotherapy. We also analyzed the relationship between fraction tumor location and characteristics and the calculated results of synchronous respiratory tracking by CyberKnife.

Results

There were no significant differences between the first four fractions (p > 0.05) for left lung lesions and no significant differences between the first five fractions for right lung lesions (p ≥ 0.05). For peripheral lung cancer, longer fractional treatment led to greater variation in grayscale (G-A: >4 fractions p < 0.05), while for central lung cancer, longer fractional treatment led to greater variation in parameters of the synchronous respiratory tracking algorithm (Uncertainty A and Uncertainty B: >4 fractions p < 0.05). There was a significant correlation between radiotherapy-graded tumor density and relevant parameters, and the correlation was strong (>0.7, p < 0.05).

Conclusion

With the increase of treatment fractions, the gray value in the patient tracking volume decreased. Patients of >4 fractions were advised to reevaluate with simulated CT and replan. For tumors with small diameter and low density, the imaging changes of volume should be closely followed during treatment. For left lung and central lung cancer, carefully select the synchronous tracking treatment with 2-view.

Stereotactic ablative radiotherapy for malignant mediastinal and hilar lymphadenopathy: a systematic review

Background

Stereotactic ablative radiotherapy (SABR) safety and efficacy for mediastinal and hilar lymphadenopathy (MHL) is not yet established, given its potential for toxicity due to the proximity to esophagus and proximal bronchial tree (PBT). This review summarized current reported outcomes of MHL SABR.

Methods

This systematic review, based on the PRISMA guidelines, was performed using MEDLINE® (PubMed®), EMBASE and Cochrane Library databases from inception until December 2018. Studies reporting outcomes from SABR specifically for MHL from all primary malignancies were included. Non- English studies, guidelines, reviews, non-peer reviewed correspondences were excluded. Only the most recent publication and/or largest cohort from a single institution would be included for analysis.

Results

From the 222 studies identified, 4 retrospective studies totaling 196 patients were included in the analysis. One study included a small number of patients receiving non-ablative doses of stereotactic radiotherapy (RT). Non-small cell lung cancer (NSCLC) was the most common primary (65%), followed by breast (8%). Median follow-up ranged between 12 and 32 months. Reported dose and fractionation ranged from 21 to 60 Gy in 3–11 fractions, with median BED10 ranged from 46–106 Gy10. Three studies reported local control (LC) rates: study 1, 97% (1-year) and 77% (5-year); study 4, 88% (2-year); and study 2, 69% (6-month) and 66% (16-month). Pooled grade 3–5 toxicity rate according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0 was 6% (n=11). Pooled SABR-related mortality (grade 5 toxicity) rate was 2% (n=4). Three SABR-related deaths from esophageal fistulae (2 to trachea, 1 to mediastinum) were reported, with all 3 having prior RT to the subcarinal nodes.

Conclusions

Our review suggested SABR for MHL to be feasible and effective, though there is a potential for serious toxicity especially in the re-irradiation scenario. Multi-institutional and/or prospective studies will help determine the therapeutic benefit of SABR in this high-risk treatment scenario.

Can high-risk CT features suggest local recurrence after stereotactic body radiation therapy for lung cancer? A systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis evaluating usefulness of high-risk CT features (HRFs) on follow-up CT in detecting local recurrence after stereotactic body radiation therapy (SBRT) in lung cancer patients.

METHODS

Pubmed and EMBASE were searched up to January 11th, 2019. We included studies that differentiated local recurrence from post-SBRT changes after SBRT on follow-up CT in lung cancer patients. Methodological quality was assessed using QUADAS-2. The association between HRFs and local recurrence were pooled in the form of odds ratio (OR) using the random effects model. Heterogeneity was examined by the Inconsistency index (I²).

RESULTS

Eight studies were included, consisting of 356 lung cancer patients. The overall prevalence of patients with local recurrence was 18.8 % (67/356). Compared with post-SBRT changes, local recurrence after SBRT more frequently demonstrated air-bronchogram disappearance (OR = 7.15), bulging margin (OR = 24.12), craniocaudal growth (OR = 26.07), enlargement after 12 months (OR = 28.11), enlarging opacity (OR = 7.92), linear margin disappearance (OR = 29.24), and sequential enlargement (OR = 83.23) (p ≤ 0.02). Pleural effusion appearance was not related with local recurrence (p = 0.82). Heterogeneity varied among HRFs (I² = 0-91 %). The quality of the studies was considered moderate.

CONCLUSIONS

Several HRFs on follow-up CT after SBRT were useful in suggesting local recurrence. These HRFs may help raise clinical suspicion of local recurrence, initiate prompt additional test for confirmation and perform subsequent proper personalized salvage treatment.

Stereotactic body radiation therapy versus fractionated radiation therapy for early-stage bronchopulmonary carcinoid

Aim

To compare trends and outcomes in early stage bronchopulmonary carcinoid (BPC) tumors treated nonoperatively with conventionally fractionated radiotherapy (CFRT) and stereotactic body radiotherapy (SBRT).

Methods/materials

We queried the National Cancer Database for primary (typical) BPC staged cT1-2N0M0 and treated nonsurgically with lung-directed radiation and ≥1 month of follow-up. Odds ratios were used to predict likelihood of SBRT treatment and multivariable Cox regression determined predictors of survival.

Results

Out of 154 patients, 84 (55%) were treated with SBRT and the remainder were treated with CFRT. Although SBRT use was 0% from 2004 to 2007, it varied from 50 to 70% per year thereafter. Propensity-matched Kaplan-Meier analysis revealed improved survival with lung SBRT (median: 66 vs 58 months; p = 0.034).

Conclusion

SBRT for early stage, primary BPC has increased over time and was associated with higher survival than CFRT.

Results of a multicentre dosimetry audit using a respiratory phantom within the EORTC LungTech trial

INTRODUCTION

The EORTC 22113-08113 LungTech trial assesses the safety and efficacy of SBRT for centrally located NSCLC. To insure protocol compliance an extensive RTQA procedure was implemented.

METHODS

Twelve centres were audited using a CIRS008A phantom. The phantom was scanned using target inserts of 7.5 mm and 12.5 mm radius in static condition. For the 7.5 mm insert a 4DCT was acquired while moving according to a cos⁶ function. Treatment plans were measured using film and an ionization chamber. Wilcoxon's signed-rank tests were performed to compare the three plans across institutions. A Spearman correlation was calculated to evaluate the influence of factors such as PTV, slice thickness and total number of monitor units on the dosimetric results.

RESULTS

The reference output dose median [min, max] variation was 0.5% [-1.1, +1.5]. The median deviations between chamber doses and point-planned doses were 1.8% [-0.1; 6.7] for the 7.5 mm and 1.1% [-2.8; 5.0] for the 12.5 mm sphere in static situation and 3.2% [-3.2; 15.7] for the dynamic situation. Film gamma median pass rates were 92.0% [68.0, 99.0] for 7.5 mm static, 96.2% [73.0, 99.0] for 12.5 mm static and 71.0% [40.0, 99.0] for 7.5 mm dynamic. Wilcoxon's signed-rank tests showed that the dynamic irradiations resulted in significantly lower gamma pass rates compared to the 12.5 mm static plan (p = 0.001). The total number of MUs per plan was correlated to both film and IC results.

CONCLUSION

An end-to-end audit was successfully performed, revealing important variations between institutions especially in dynamic irradiations. This shows the importance of dosimetry audits and the potentials for further technique and methodology improvements.

Safety and Effectiveness of Stereotactic Ablative Radiotherapy for Ultra-Central Lung Lesions: A Systematic Review

INTRODUCTION

The safety and effectiveness of stereotactic ablative radiotherapy (SABR) in patients with ultra-central lung tumors is currently unclear. We performed a systematic review to summarize existing data and identify trends in treatment-related toxicity and local control following SABR in patients with ultra-central lung lesions.

METHODS

We performed a systematic review based on the Preferred Reporting Items for Systemic Reviews and Meta-Analyses guidelines using the PubMed and Embase databases. The databases were queried from dates of inception until September 27, 2018. Studies in the English language that reported treatment-related toxicity and local control outcomes post-SABR for patients with ultra-central lung lesions were included. Guidelines, reviews, non-peer reviewed correspondences, studies focused on re-irradiation, and studies with fewer than five patients were excluded.

RESULTS

A total of 446 studies were identified, with 10 meeting all criteria for inclusion. The total sample size from the identified studies was 250 ultra-central lung patients and all studies were retrospective in design. Radiotherapy dose and fractionation ranged from 30 to 60 Gy in 3 to 12 fractions, with biologically effective doses (BED₁₀) ranging from 48 to 138 Gy₁₀ (median, 78-103 Gy₁₀). Median treatment-related grade 3 or greater toxicity was 10% (range, 0-50%). Median treatment-related mortality was 5% (range, 0-22%), most commonly from pulmonary hemorrhage (55%). High-risk indicators for SABR-related mortality included gross endobronchial disease, maximum dose to the proximal bronchial tree greater than or equal to 180 Gy₃ (BED₃, corresponding to 45 Gy in 5 fractions or 55 Gy in 8 fractions), peri-SABR bevacizumab use, and antiplatelet/anticoagulant use. Median 1-year local control rate was 96% (range, 63%-100%) and 2-year local control rate was 92% (range, 57%-100%).

CONCLUSIONS

SABR for ultra-central lung lesions appears feasible but there is a potential for severe toxicity in patients receiving high doses to the proximal bronchial tree, those with endobronchial disease, and those receiving bevacizumab or anticoagulants around the time of SABR. Prospective studies are required to establish the optimal doses, volumes, and normal tissue tolerances for SABR in this patient population.

Stereotactic body radiation therapy in early-stage NSCLC: historical review, contemporary evidence and future implications

Clinical use of stereotactic body radiation therapy (SBRT) has increased dramatically over the last 2 decades and is the current standard-of-care in cases of inoperable early stage non-small-cell lung cancer. While surgical resection remains the standard-of-care for operable patients, several ongoing clinical trials are investigating the role of SBRT in these operative candidates as well. Taking into consideration the expanding role and utility of SBRT, this paper will: review the historical basis of SBRT; examine landmark trials establishing the framework for the current body of evidence; discuss areas of active and future research; and identify epidemiological trends that are likely to further increase the use of SBRT.

The evolving toxicity profile of SBRT for lung cancer

Stereotactic body radiation therapy (SBRT) is an effective and well tolerated treatment for early stage non-small cell lung cancer (NSCLC). The high doses used in thoracic SBRT can sometimes cause adverse effects ranging from mild fatigue and transient esophagitis to fatal events such as pneumonitis or hemorrhage. Efforts continue to expand in both the utility of this technique as well as our understanding of the mechanisms of the adverse effects it can cause. In this review, we discuss the current literature regarding the potential mechanisms, dosimetric constraints and toxicities associated with SBRT alone and in conjunction with definitive chemoradiotherapy and immunotherapy. As the use of SBRT expands to these spheres, we examine the available recommendations for mitigating potential associated treatment related toxicities.

Stereotactic body radiotherapy for central lung tumors: Finding the balance between safety and efficacy in the "no fly" zone

BACKGROUND

Stereotactic body radiotherapy (SBRT) has emerged as a highly effective technique to treat medically inoperable non-small cell lung cancer (NSCLC). Doses must be chosen carefully when treating central lesions because of the potential for significant toxicity. This study reviews the outcomes of a cohort of patients with central lung tumors treated with SBRT.

METHODS

We identified 18 patients (12 women, 6 men) with central lesions that were treated with SBRT at our institution. Overall survival and local, regional, and distant control rates were assessed by Kaplan-Meier methodology. Correlations with outcomes were determined by multivariate analysis via Cox regression models.

RESULTS

Eighty-nine percent of patients had a pathological diagnosis of NSCLC. The median dose to the planning target volume was 40 Gy (range: 30-50) in five fractions, yielding a median biologic equivalent dose (BED₁₀ ) of 72 (range: 48-100). The median planning target volume was 34 cc (range: 13.3-89). Local control was 87% at one year. Median overall survival was 45 months, with a two-year rate of 61%. The two-year regional control rate was 87%. BED₁₀ > 72 predicted improved progression-free survival, with one-year rates of 100% versus 40% with increased BED (P = 0.012). No grade 3 or higher acute or late toxicity was observed.

CONCLUSIONS

Lung SBRT to central lesions is safe and effective when using five fraction regimens. BED₁₀ < 72 predicted disease progression, highlighting the importance of choosing an effective dose fractionation scheme, which must in turn be balanced with potential toxicity.

[Stereotactic Body Radiotherapy for Centrally Located Non-small Cell Lung Cancer]

A few study has proven that about 90% of local control rates might be benefit from stereotactic body radiotherapy (SBRT) for patients with medically inoperable stage I non-small cell lung cancer (NSCLC), it is reported SBRT associated overall survival and tumor specific survival is comparable with those treated with surgery. SBRT has been accepted as the first line treatment for inoperable patients with peripheral located stage I NSCLC. However, the role of SBRT in centrally located lesions is controversial for potential toxic effects from the adjacent anatomical structure. This paper will review the definition, indication, dose regimens, dose-volume constraints for organs at risk, radiation technology, treatment side effect of centrally located NSCLC treated with SBRT and stereotactic body proton therapy.