Stereotactic Radiotherapy for Ultra-Central Lung Oligometastases in Non-Small-Cell Lung Cancer

Advances of PET/CT in Target Delineation of Lung Cancer Before Radiation Therapy

In the clinical management of lung cancer, radiotherapy remains a cornerstone of multimodal treatment strategies, often used alongside surgery or in combination with systemic therapies such as chemotherapy, tyrosine kinase inhibitors, and immune checkpoint inhibitors. While conventional imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) continue to play a central role in staging, response assessment, and radiotherapy planning, advanced imaging techniques, particularly [18F]FDG PET/CT, are being increasingly integrated into routine clinical practice. These advanced techniques address the limitations of standard imaging by providing insight into molecular and metabolic tumor characteristics, enabling precise tumor visualization, accurate target volume delineation, and early treatment response assessment. This review examines the role of radiotherapy in the multidisciplinary management of lung cancer, detailing current concepts of morphological and functional imaging for staging and treatment planning. It also highlights the growing importance of PET-based radiotherapy planning, emphasizing its contributions to target volume definition and predictive value for treatment outcomes. Recent methodological advances, including the integration of artificial intelligence (AI), radiomics, technical innovations, and novel PET ligands, are discussed, highlighting their potential to improve the precision, efficacy, and personalization of lung cancer radiotherapy planning.

Recent Advances and Current Challenges in Stereotactic Body Radiotherapy for Ultra-Central Lung Tumors

Stereotactic body radiotherapy has been established as a viable treatment option for inoperable early-stage non-small cell lung cancer or secondary lesions mainly in oligoprogressive/oligometastatic scenarios. Treating lesions in the so-called "no flight zone" has always been challenging and conflicting data never cleared how to safely treat these lesions. This is truer considering ultra-central lesions, i.e., directly abutting or whose PTV is overlapping critical mediastinal organs. While historical retrospective data are abundant but mostly heterogenous in terms of the definition of ultra-central lesions, dosing regimens and outcomes, prospective data remain scarce, even though recently published studies have given new encouraging results for such delicate treatment scenarios. For this reason, we aimed to review and summarize current knowledge on stereotactic radiation treatment for ultra-central thoracic lesions, highlighting the most recent advances and the messages that can be taken from them. Lastly, we propose a workflow of the necessary steps to identify and treat such patients, therefore helping in elucidating the advantages and caveats of such treatment options.

Stereotactic Body Radiation Therapy for Primary Lung Cancer and Metastases: A Case-Based Discussion on Challenging Cases

PURPOSE

Data informing the safety, efficacy, treatment logistics, and dosimetry of stereotactic body radiation therapy (SBRT) for lung tumors has primarily been derived from patients with favorably located solitary tumors. SBRT is now considered a standard-of-care treatment for inoperable early-stage non-small cell lung cancer and lung metastases, and therefore extrapolation beyond this limited foundational patient population remains an active source of interest.

METHODS AND MATERIALS

This case-based discussion provides a practical framework for delivering SBRT to challenging, yet frequently encountered, cases in radiation oncology. The cases highlighted herein include the use of SBRT for ultracentral tumors, multiple tumors, and reirradiation. Patient characteristics, fractionation, prescription dose, treatment technique, and dose constraints are discussed. Relevant literature to these cases is summarized to provide a framework for the treatment of similar patients.

RESULTS

Treatment of challenging cases with lung SBRT requires many considerations, including treatment intent, fractionation selection, tumor localization, and plan optimization. In such scenarios, patient selection is critical to understanding the risk-benefit profile of an SBRT approach despite significant advances in delivery techniques and safety.

CONCLUSIONS

A case-based discussion was developed by the Radiosurgery Society to provide a practical guide to the common challenging scenarios noted above affecting patients with lung tumors. A multidisciplinary approach should guide the treatment of such cases to maximize the therapeutic window.

Repeat biopsy versus initial biopsy in terms of complication risk factors and clinical outcomes for patients with non-small cell lung cancer: a comparative study of 113 CT-guided needle biopsy of lung lesions

Objectives

The safety and feasibility of repeat biopsy after systemic treatment for non-small cell lung cancer have received extensive attention in recent years. The purpose of this research was to compare complication rates between initial biopsy and rebiopsy in non-small cell lung cancer patients with progressive disease and to assess complication risk factors and clinical results after rebiopsy.

Methods

The study included 113 patients initially diagnosed with non-small cell lung cancer who underwent lung biopsy at initial biopsy and rebiopsy after progression while on epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and/or chemotherapy from January 2018 to December 2021. We compared the incidence of complications between the initial biopsy and rebiopsy and analyzed the predictors factors that influenced complications in patients who underwent rebiopsy.

Results

The successful rate of rebiopsy was 88.5% (100/113). With the exception of two cases where lung adenocarcinoma changed into small cell lung cancer with gefitinib treatment, 98 individuals retained their initial pathological type. The secondary EGFR T790M mutation accounts for 55.6% of acquired resistance. The total number of patients with complications in initial biopsy was 25 (22.1%) and 37 (32.7%) in the rebiopsy. The incidence of pulmonary hemorrhage increased from 7.1% at the initial biopsy to 10.6% at rebiopsy, while the incidence of pneumothorax increased from 14.2% to 20.4%. Compared with the initial biopsy, the incidence of overall complications, parenchymal hemorrhage, and pneumothorax increased by 10.6%, 3.5%, and 6.2%, respectively. In all four evaluations (pneumorrhagia, pneumothorax, pleural reaction, and overall complication), there were no significant differences between the rebiopsy and initial biopsy (all p > 0.05). The multivariate logistic regression analysis suggested that male sex (odds ratio [OR] = 5.064, p = 0.001), tumor size ≤ 2 cm (OR = 3.367, p = 0.013), EGFR-TKIs with chemotherapy (OR = 3.633, p =0.023), and transfissural approach (OR = 7.583, p = 0.026) were independent risk factors for overall complication after rebiopsy.

Conclusion

Compared with the initial biopsy, the complication rates displayed a slight, but not significant, elevation in rebiopsy. Male sex, tumor size ≤ 2 cm, transfissural approach, and EGFR-TKIs combined with chemotherapy were independent risk factors for rebiopsy complications.

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

PURPOSE

A systematic review of treatment characteristics, outcomes, and treatment-related toxicities of stereotactic body radiation therapy (SBRT) for pulmonary oligometastases served as the basis for development of this International Stereotactic Radiosurgery Society (ISRS) practice guideline.

METHODS

In accordance with PRISMA guidelines, a systematic review was performed of retrospective series with ≥50 patients/lung metastases, prospective trials with ≥25 patients/lung metastases, analyses of specific high-risk situations, and all randomized trials published between 2012 and July 2022 in the MEDLINE or Embase database using the key words "lung oligometastases", "lung metastases", "pulmonary metastases", "pulmonary oligometastases", "stereotactic body radiation therapy (SBRT)" and "stereotactic ablative body radiotherapy (SBRT)". Weighted random effects models were used to calculate pooled outcomes estimates.

RESULTS

Of the 1884 articles screened, 35 analyses (27 retrospective-, 5 prospective, and 3 randomized trials) reporting on treatment of >3600 patients and >4650 metastases were included. The median local control was 90 % (Range: 57-100 %) at 1 year and 79 % (R: 70-96 %) at 5 years. Acute toxicity ≥3 was reported for 0.5 % and late toxicity ≥3 for 1.8 % of patients. A total of 21 practice recommendations covering the areas of staging & patient selection (n = 10), SBRT treatment (n = 10), and follow-up (n = 1) were developed, with agreements rates of 100 %, except for recommendation 13 (83 %).

CONCLUSION

SBRT represents an effective definitive local treatment modality combining high local control rates with low risk of radiation-induced toxicities.

Safety and Effectiveness of Percutaneous Image-Guided Thermal Ablation of Juxtacardiac Lung Tumors

PURPOSE

To evaluate the safety and effectiveness of percutaneous image-guided thermal ablation (IGTA) for juxtacardiac lung tumors.

MATERIALS AND METHODS

This bi-institutional retrospective cohort study included 23 consecutive patients (13 [57%] male; mean age, 55 years ± 18) with 30 juxtacardiac lung tumors located ≤10 mm from the pericardium treated in 28 IGTA sessions (25 sessions of cryoablation and 3 sessions of microwave ablation) between April 2008 and August 2022. The primary outcome was any adverse cardiac event within 90 days after ablation. Secondary outcomes included noncardiac adverse events, local tumor progression-free survival (LT-PFS), and the cumulative incidence of local tumor progression with death as a competing risk. Two tumors treated without curative intent or follow-up imaging were considered in the safety analysis but not in the progression analysis.

RESULTS

The median imaging follow-up duration was 22 months (interquartile range [IQR], 10-53 months). Primary technical success was achieved in 25 (89%) ablations. No adverse cardiac events attributable to IGTA occurred. One patient experienced a phrenic nerve injury. The median LT-PFS duration was 59 months (IQR, 32-73 months). At 1, 3, and 5 years, LT-PFS was 90% (95% CI, 78%-100%), 74% (CI, 53%-100%), and 45% (CI, 20%-97%), respectively, and the cumulative incidence of local tumor progression was 4.3% (CI, 0.29%-19%), 11% (CI, 1.6%-30%), and 26% (CI, 3.3%-58%), respectively.

CONCLUSIONS

IGTA is safe and effective for lung tumors located ≤10 mm from the pericardium. No adverse cardiac events were not observed within 90 days after ablation.

Survival and Prognostic Factors of Ultra-Central Tumors Treated with Stereotactic Body Radiotherapy

Introduction: Stereotactic body radiotherapy (SBRT) reported excellent outcomes and a good tolerability profile in case of central lung tumors, as long as risk-adapted schedules were adopted. High grade toxicity was more frequently observed for tumors directly touching or overlapping the trachea, proximal bronchial tree (PBT), and esophagus. We aim to identify prognostic factors associated with survival for Ultra-Central (UC) tumors. Methods: We retrospectively evaluated patients treated with SBRT for primary or metastatic UC lung tumors. SBRT schedules ranged from 45 to 60 Gy. Results: A total number of 126 ultra-central lung tumors were reviewed. The Median follow-up time was 23 months. Median Overall Survival (OS) and Progression Free Survival (PFS) was 29.3 months and 16 months, respectively. Local Control (LC) rates at 1 and 2 were 86% and 78%, respectively. Female gender, age < 70 years, and tumor size < 5 cm were significantly associated with better OS. The group of patients with tumors close to the trachea but further away from the PBT also correlated with better OS. The acute G2 dysphagia, cough, and dyspnea were 11%, 5%, and 3%, respectively. Acute G3 dyspnea was experienced by one patient. Late G3 toxicity was reported in 4% of patients. Conclusion: risk-adaptive SBRT for ultra-central tumors is safe and effective, even if it remains a high-risk clinical scenario.

PET/CT for Target Delineation of Lung Cancer Before Radiation Therapy

In clinical routine of patients suffering from lung cancer, radiotherapy/radiation oncology represents one of the therapeutic hallmarks in the multimodal treatment besides or in combination with other local treatments such as surgery, but also systemic treatments such as chemotherapy, tyrosine kinase, and immune check-point inhibitors. Conventional morphological imagings such as CT or MR are commonly used for staging, response assessment, but also for radiotherapy planning. However, advanced imaging techniques such as PET do continuously get increasing access to clinical routine overcoming limitations of standard imaging techniques by visualizing and quantifying molecular processes such as glucose metabolism, which is also of relevance for radiotherapy planning. This review article summarizes the current place of radiotherapy within the treatment regimens of patients with lung cancer and elucidates current concepts of standard morphological imaging for staging and radiotherapy planning. Moreover, the place of PET-based radiotherapy planning in a clinical context is presented and current methodological/technical advances that do comprise a potential role for radiotherapy planning in lung cancer patients are discussed.

Bronchial stenosis in central pulmonary tumors treated with Stereotactic Body Radiation Therapy: Bronchial stenosis in central lung tumors after SBRT

PURPOSE

Stereotactic body radiotherapy (SBRT) in lung tumors has an excellent local control due to the high delivered dose. Proximity of the proximal bronchial tree (PBT) to the high dose area may result in pulmonary toxicity. Bronchial stenosis is an adverse event that can occur after high dose to the PBT. Literature on the risk of developing bronchial stenosis is limited. We therefore evaluated the risk of bronchial stenosis for tumors central to the PBT and correlated the dose to the bronchi.

METHODS AND MATERIALS

Patients with a planning tumor volume (PTV) ≤2cm from PBT receiving SBRT (8 × 7.5Gy) between 2015-2019 were retrospectively reviewed. Main bronchi and lobar bronchi were manually delineated. Follow-up CT-scans were analyzed for bronchial stenosis and atelectasis. Bronchial stenosis was assessed using CTCAEv4. Patient, tumor, dosimetric factors and survival were evaluated between patients with and without stenosis using uni- and multivariate and Kaplan Meier analysis.

RESULTS

Fifty-one patients were analyzed with a median age of 70 years and WHO≤1 in 92.2%. Median follow-up was 36 months (IQR 19.6-45.4) and median OS 48 months (IQR 21.5-59.3). In fifteen patients (29.4%) bronchial stenosis was observed on FU-CT-scan. Grade 1 stenosis was seen in 21.6% (n=11), grade 2 in 7.8% (n=4). No grade ≥3 stenosis was observed. Median time to stenosis was 9.6 months (IQR 4.4-19.2). Patients who developed stenosis had significantly larger gross tumor volume (GTV) with a median of 19cc (IQR 7.7-63.2) versus 5.2cc (IQR 1.7-11.3, p<0.01). Prognostic factors in multivariate analysis for stenosis were age (p=0.03; OR 1.1), baseline dyspnea (p=0.02 OR 7.7) and the mean lobar bronchus dose (p=0.01; OR 1.1).

CONCLUSION

Low grade (≤2) lobar bronchial stenosis is a complication in approximately one third of patients following SBRT for lung tumors with a PTV ≤2cm from PBT. Prognostic risk factors were age, baseline dyspnea and mean dose on a lobar bronchus.

Oligometastatic Disease in Non-Small-Cell Lung Cancer: An Update

Simple Summary

Approximately 7–50% of patients with non-small-cell lung cancer (NSCLC) develop oligometastases, which are new tumors found in another part of the body, arising from cancer cells of the original tumor that have travelled through the body. In recent years, these patients have been increasingly regarded as a distinct group that could benefit from treatment that intends to cure the disease, rather than palliative care, to achieve a better clinical outcome. Various treatment procedures have been developed for treating NSCLC patients with different oligometastatic sites. In addition, the newly proposed uniform definition for oligometastases as well as ongoing trials may lead to increased appropriate patient selection and evaluation of treatment effectiveness. The aim of this review article is to summarize the latest evidence regarding optimal management strategies for NSCLC patients with oligometastases.

Abstract

Oligometastatic non-small-cell lung cancer (NSCLC) is a distinct entity that is different from localized and disseminated diseases. The definition of oligometastatic NSCLC varies across studies in past decades owing to the use of different imaging modalities; however, a uniform definition of oligometastatic NSCLC has been proposed, and this may facilitate trial design and evaluation of certain interventions. Patients with oligometastatic NSCLC are candidates for curative-intent management, in which local ablative treatment, such as surgery or stereotactic radiosurgery, should be instituted to improve clinical outcomes. Although current guidelines recommend that local therapy for thoracic and metastatic lesions should be considered for patients with oligometastatic NSCLC with stable disease after systemic therapy, optimal management strategies for different oligometastatic sites have not been established. Additionally, the development of personalized therapies for individual patients with oligometastatic NSCLC to improve their quality of life and overall survival should also be addressed. Here, we review relevant articles on the management of patients with oligometastatic NSCLC and categorize the disease according to the site of metastases. Ongoing trials are also summarized to determine future directions and expectations for new treatment modalities to improve patient management.

Toxicity and efficacy of stereotactic body radiotherapy for ultra-central lung tumours: a single institution real life experience

OBJECTIVES

The use of stereotactic body radiotherapy (SBRT) to treat ultra-central lung tumours remains more controversial than for peripheral and central tumours. Our objective was to assess toxicities, local control (LC) rate and survival data in patients with ultra-central lung tumours treated with SBRT.

METHODS

We conducted a retrospective and monocentric study about 74 patients with an ultra-central lung tumour, consecutively treated between 2012 and 2018. Ultra-central tumours were defined as tumours whose planning target volume overlapped one of the following organs at risk (OARs): the trachea, right and left main bronchi, intermediate bronchus, lobe bronchi, oesophagus, heart.

RESULTS

Median follow-up was 25 months. Two patients (2.7%) showed Grade 3 toxicity. No Grade 4 or 5 toxicity was observed. 11% of patients experienced primary local relapse. LC rate was 96.7% at 1 year and 87.6% at 2 years. Median progression free survival was 12 months. Median overall survival was 31 months.

CONCLUSION

SBRT for ultra-central tumours remains safe and effective as long as protecting organs at risk is treatment-planning priority.

ADVANCES IN KNOWLEDGE

The present study is one of the rare to describe exclusively ultra-central tumours through real-life observational case reports. Globally, literature analysis reveals a large heterogeneity in ultra-central lung tumours definition, prescribed dose, number of fractions. In our study, patients treated with SBRT for ultra-central lung tumours experienced few Grade 3 toxicities (2.7%) and no Grade 4 or 5 toxicities, due to the highest compliance with dose constraints to OARs. LC remained efficient.

Suitability of Metastatic Lung Tumors for Stereotactic Body Radiotherapy

We investigated factors influencing local control of lung metastases treated with stereotactic body radiotherapy (SBRT) and determined the type of lesions for which SBRT is more suitable. Ninety-six patients and 196 tumors were included. Median follow-up duration was 32.0 months (range 4.7-95.8). The two-year local recurrence rate was 15.2% (95% confidence interval: 10.2-21.3). Multivariate analysis revealed biological effective dose, ultracentral tumor location, reirradiation, and prior chemotherapy as significant factors. SBRT is suitable for lung metastases, especially for peripheral tumors and those located in the inner lung parenchyma. For ultracentral lesions and recurrent lesions after SBRT, metastasectomy is recommended.

Late Toxicity and Long-Term Local Control in Patients With Ultra-Central Lung Tumours Treated by Intensity-Modulated Radiotherapy-Based Stereotactic Ablative Body Radiotherapy With Homogenous Dose Prescription

AIMS

To report late toxicity and long-term outcomes of intensity-modulated radiotherapy (IMRT)-based stereotactic ablative body radiotherapy (SABR) in patients with ultra-central lung tumours.

MATERIALS AND METHODS

This is a single-institution retrospective analysis of patients treated with SABR for ultra-central tumours between May 2008 and April 2016. Ultra-central location was defined as tumour (GTV) abutting or involving trachea, main or lobar bronchi. Respiratory motion management and static-field dynamic-IMRT were used, with dose prescribed homogeneously (maximum <120%). Descriptive analysis, Kaplan-Meier method, log-rank test and Cox regression were used to assess outcomes.

RESULTS

Sixty-five per cent of patients had inoperable primary non-small cell lung cancer and 35% had lung oligometastases. The median age was 72 (range 34-85) years. The median gross tumour volume and planning target volume (PTV) were 19.6 (range 1.7-203.3) cm³ and 57.4 (range 7.7-426.6) cm³, respectively. The most commonly used dose fractionation was 60 Gy in eight fractions (n = 51, 87.8%). Median BED₁₀ for D98%PTV and D2%PTV were 102.6 Gy and 115.06 Gy, respectively. With a median follow-up of 26.5 (range 3.2-100.5) months, fatal haemoptysis occurred in five patients (8.7%), of which two were directly attributable to SABR. A statistically significant difference was identified between median BED₃ for 4 cm³ of airway, for patients who developed haemoptysis versus those who did not (147.4 versus 47.2 Gy, P = 0.005). At the last known follow-up, 50 patients (87.7%) were without local recurrence. Freedom from local progression at 2 and 4 years was 92 and 79.8%, respectively. The median overall survival was 34.3 (95% confidence interval 6.1-61.6) months. Overall survival at 2 and 4 years was 55.1 and 41.2%, respectively.

CONCLUSION

In patients with high-risk ultra-central lung tumours, IMRT-based SABR with homogenous dose prescription achieves high local control, similar to that reported for peripheral tumours. Although fatal haemoptysis occurred in 8.7% of patients, a direct causality with SABR was evident in only 3%. Larger studies are warranted to ascertain factors associated with outcomes, especially toxicity, and identify patients who would probably benefit from this treatment.

New Therapeutic Strategies for Lung Cancer

Non-small cell lung cancer (NSCLC) accounts for approximately 27% of all cancer-related deaths worldwide, thus representing a major health problem [...].