A Collaborative Analysis of Stereotactic Lung Radiotherapy Outcomes for Early-Stage Non–Small-Cell Lung Cancer Using Daily Online Cone-Beam Computed Tomography Image-Guided Radiotherapy

A Propensity-Matched Comparison Between Minimally Invasive Surgery and Stereotactic Radiotherapy in the Treatment of Clinical Stage IA Non-Small-Cell Lung Cancer (NSCLC)

BACKGROUND

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death globally, with stage IA NSCLC presenting a unique opportunity for curative interventions. The efficacy of minimally invasive surgery (MIS) vs. stereotactic ablative radiotherapy (SABR) remains debated due to limited direct comparative data.

METHODS

This multicenter observational study analyzed data from 1014 patients diagnosed with clinical stage IA NSCLC (2015-2021) and treated with MIS (including VATS and RATS) or SABR. After propensity score matching, 234 patients (117 per group) were included. Matching balanced age, ECOG performance status, Charlson Comorbidity Index, lung function, and histological subtype to compare overall survival (OS), freedom from recurrence (FFR), and recurrence rates.

RESULTS

The mean follow-up was 35 months for MIS and 33 months for SABR. The matched cohort (n = 234) showed superior 5-year locoregional control (LRC) rates for MIS (93%) vs. SABR (88%). FFS at 2 and 5 years was higher for MIS (93.5% and 90.3%) than SABR (82.1% and 77.9%; P = .010). OS was significantly higher in MIS, with a hazard ratio of 1.60 (95% CI: 1.11-2.31). Early mortality rates were 2.6% for MIS at 30 and 90 days. SABR exhibited no 30-day mortality and a 90-day rate of 1.7%.

CONCLUSION

MIS is associated with higher OS, LRC and FFR, but higher treatment-related mortality compared to SABR for stage IA NSCLC. This study supports the preference for surgical interventions where feasible. While future randomized controlled trials may provide more insights, this observational study contributes valuable evidence to guide clinical decision-making.

Structure-specific rigid dose accumulation dosimetric analysis of ablative stereotactic MRI-guided adaptive radiation therapy in ultracentral lung lesions

BACKGROUND

Definitive local therapy with stereotactic ablative radiation therapy (SABR) for ultracentral lung lesions is associated with a high risk of toxicity, including treatment related death. Stereotactic MR-guided adaptive radiation therapy (SMART) can overcome many of the challenges associated with SABR treatment of ultracentral lesions.

METHODS

We retrospectively identified 14 consecutive patients who received SMART to ultracentral lung lesions from 10/2019 to 01/2021. Patients had a median distance from the proximal bronchial tree (PBT) of 0.38 cm. Tumors were most often lung primary (64.3%) and HILUS group A (85.7%). A structure-specific rigid registration approach was used for cumulative dose analysis. Kaplan-Meier log-rank analysis was used for clinical outcome data and the Wilcoxon Signed Rank test was used for dosimetric data.

RESULTS

Here we show that SMART dosimetric improvements in favor of delivered plans over predicted non-adapted plans for PBT, with improvements in proximal bronchial tree DMax of 5.7 Gy (p = 0.002) and gross tumor 100% prescription coverage of 7.3% (p = 0.002). The mean estimated follow-up is 17.2 months and 2-year local control and local failure free survival rates are 92.9% and 85.7%, respectively. There are no grade ≥ 3 toxicities.

CONCLUSIONS

SMART has dosimetric advantages and excellent clinical outcomes for ultracentral lung tumors. Daily plan adaptation reliably improves target coverage while simultaneously reducing doses to the proximal airways. These results further characterize the therapeutic window improvements for SMART. Structure-specific rigid dose accumulation dosimetric analysis provides insights that elucidate the dosimetric advantages of SMART more so than per fractional analysis alone.

Predictive clinical and dosimetric parameters for risk of relapse in early-stage non-small cell lung cancer treated by SBRT: A large single institution experience

Purpose

To evaluate the impact of dosimetric parameters on efficacy of stereotactic body radiation therapy (SBRT) in early-stage non-small cell lung cancer (ES-NSCLC), using Hypofractionated Treatment Effects in the Clinic (HyTEC) reporting standards.

Methods

From April 2010 to December 2020, 497 patients who received SBRT for ES-NSCLC at the University Hospital of Liège were retrospectively enrolled. A total dose of 40 to 60 Gy in 3-5 fractions (72-180 Gy biologically effective dose with an α/β ratio of 10 (BED10)) was prescribed to the 80 % isodose line of the PTV. Potential clinical and dosimetric predictors of recurrence, overall survival (OS) and disease specific survival (DSS) were evaluated using univariate and multivariate analyses.

Results

After a median follow-up of 32 months (range 3-143 months), the local control and disease-free survival (DFS) rates at 3 years were 91 % (95 % CI: 90 %-93 %) and 75 % (95 % CI: 73 %-77 %), respectively. The median OS was 41.6 months and the median DSS was not reached. On multivariate analysis, a higher gross tumor volume (GTV) Dmax (BED10) (cut-off 198 Gy) and a larger percent of the GTV receiving ≥110 % of the prescribed dose were predictive of a better local control, only GTV volume was correlated with DSS and no parameter was correlated with OS and regional or distant recurrences.

Conclusion

Lung SBRT for ES-NSCLC in 3 to 5 fractions resulted in high local control rates. A higher percent of GTV receiving ≥110 % of the prescribed dose and a higher GTV Dmax (BED10) seem to allow a better local control.

Five-Day Spacing of Two Fractionated Ablative Radiotherapies Enhances Antitumor Immunity

PURPOSE

This study aimed to enhance tumor control and abscopal effects by applying diverse stereotactic ablative radiation therapy (SABR) schedules.

METHODS AND MATERIALS

FSaII, CT-26, and 4T1 cells were used for tumor growth delay and lung metastases analysis after 1- or 5-day intervals radiation therapy (RT) with 40, 20, and 20 Gy, respectively. Immunodeficient BALB/c-nude, immunocompetent C3H, and BALB/c mouse models were used. For immune monitoring, FSaII tumors were analyzed using flow cytometry, immunofluorescence staining, and real-time quantitative reverse transcription polymerase chain reaction. The spleens were used for the ELISpot assay and flow cytometry to determine effector CD8 T cells. For abscopal effect analysis in CT-26 tumors, the volume of the nonirradiated secondary tumors was measured after primary tumors were irradiated with 1-day or 5-day intervals.

RESULTS

Contrary to the high-dose 1-day interval RT, the 5-day interval RT significantly delayed tumor growth in immunocompetent mice, which was not observed in immunodeficient mice. In addition, the 5-day interval RT significantly reduced the number of lung metastases in FSaII and CT-26 tumors. Five-day spacing was more effective than 1-day interval in enhancing the antitumor immunity via increasing the secretion of tumor-specific IFN-γ, activating the CD8 T cells, and suppressing the monocytic myeloid-derived suppressor cells. The 5-day spacing inhibited nonirradiated secondary tumor growth more effectively than did the 1-day interval.

CONCLUSIONS

Compared with the 1-day interval RT, the 5-day interval RT scheme demonstrated enhanced antitumor immunity of CD8 T cells associated with inhibition of myeloid-derived suppressor cells. Enhancing antitumor immunity leads to significant improvements in both primary tumor control and the abscopal effect.

Dosimetric Validation for Prospective Clinical Trial of GRID Collimator-Based Spatially Fractionated Radiation Therapy: Dose Metrics Consistency and Heterogeneous Pattern Reproducibility

PURPOSE

Dose heterogeneity within a tumor target is likely responsible for the biologic effects and local tumor control from spatially fractionated radiation therapy (SFRT). This study used a commercially available GRID-pattern dose mudulated nonuniform radiation therapy (GRID) collimator to assess the interplan variability of heterogeneity dose metrics in patients with various bulky tumor sizes and depths.

METHODS AND MATERIALS

The 3-dimensional heterogeneity metrics of 14 bulky tumors, ranging from 155 to 2161 cm3 in volume, 6 to 23 cm in equivalent diameter, and 3 to 13 cm in depth, and treated with GRID collimator-based SFRT were studied. A prescription dose of 15 Gy was given at the tumor center with 6 MV photons. The dose-volume histogram indices, dose heterogeneity parameters, and peak/valley dose ratios were derived; the equivalent uniform doses of cancer cells with various radiosensitivities in each plan were estimated. To account for the spatial fractionation, high dose core number density of the tumor target was defined and calculated.

RESULTS

Among 14 plans, the dose-volume histogram indices D5, D10, D50, D90, and D95 (doses covering 5%, 10%, 50%, 90%, and 95% of the target volume) were found within 10% variation. The dose ratio of D10/D90 also showed a moderate consistency (range, 3.9-5.0; mean, 4.4). The equivalent uniform doses were consistent, ranging from 4.3 to 5.5 Gy, mean 4.6 Gy, for radiosensitive cancer cells and from 5.8 to 6.9 Gy, mean 6.2 Gy, for radioresistant cancer cells. The high dose core number density was within 20% among all plans.

CONCLUSIONS

GRID collimator-based SFRT delivers a consistent heterogeneity dose distribution and high dose core density across bulky tumor plans. The interplan reproducibility and simplicity of GRID therapy may be useful for certain clinical indications and interinstitutional clinical trial design, and its heterogeneity metrics may help guide multileaf-collimator-based SFRT planning to achieve similar or further optimized dose distributions.

[Prevention, Diagnosis, Therapy, and Follow-up of Lung Cancer - Interdisciplinary Guideline of the German Respiratory Society and the German Cancer Society - Abridged Version]

The current S3 Lung Cancer Guidelines are edited with fundamental changes to the previous edition based on the dynamic influx of information to this field:The recommendations include de novo a mandatory case presentation for all patients with lung cancer in a multidisciplinary tumor board before initiation of treatment, furthermore CT-Screening for asymptomatic patients at risk (after federal approval), recommendations for incidental lung nodule management , molecular testing of all NSCLC independent of subtypes, EGFR-mutations in resectable early stage lung cancer in relapsed or recurrent disease, adjuvant TKI-therapy in the presence of common EGFR-mutations, adjuvant consolidation treatment with checkpoint inhibitors in resected lung cancer with PD-L1 ≥ 50%, obligatory evaluation of PD-L1-status, consolidation treatment with checkpoint inhibition after radiochemotherapy in patients with PD-L1-pos. tumor, adjuvant consolidation treatment with checkpoint inhibition in patients withPD-L1 ≥ 50% stage IIIA and treatment options in PD-L1 ≥ 50% tumors independent of PD-L1status and targeted therapy and treatment option immune chemotherapy in first line SCLC patients.Based on the current dynamic status of information in this field and the turnaround time required to implement new options, a transformation to a "living guideline" was proposed.

A combined predictive model based on radiomics features and clinical factors for disease progression in early-stage non-small cell lung cancer treated with stereotactic ablative radiotherapy

Purpose

To accurately assess disease progression after Stereotactic Ablative Radiotherapy (SABR) of early-stage Non-Small Cell Lung Cancer (NSCLC), a combined predictive model based on pre-treatment CT radiomics features and clinical factors was established.

Methods

This study retrospectively analyzed the data of 96 patients with early-stage NSCLC treated with SABR. Clinical factors included general information (e.g. gender, age, KPS, Charlson score, lung function, smoking status), pre-treatment lesion status (e.g. diameter, location, pathological type, T stage), radiation parameters (biological effective dose, BED), the type of peritumoral radiation-induced lung injury (RILI). Independent risk factors were screened by logistic regression analysis. Radiomics features were extracted from pre-treatment CT. The minimum Redundancy Maximum Relevance (mRMR) and the Least Absolute Shrinkage and Selection Operator (LASSO) were adopted for the dimensionality reduction and feature selection. According to the weight coefficient of the features, the Radscore was calculated, and the radiomics model was constructed. Multiple logistic regression analysis was applied to establish the combined model based on radiomics features and clinical factors. Receiver Operating Characteristic (ROC) curve, DeLong test, Hosmer-Lemeshow test, and Decision Curve Analysis (DCA) were used to evaluate the model’s diagnostic efficiency and clinical practicability.

Results

With the median follow-up of 59.1 months, 29 patients developed progression and 67 remained good controlled within two years. Among the clinical factors, the type of peritumoral RILI was the only independent risk factor for progression (P< 0.05). Eleven features were selected from 1781 features to construct a radiomics model. For predicting disease progression after SABR, the Area Under the Curve (AUC) of training and validation cohorts in the radiomics model was 0.88 (95%CI 0.80-0.96) and 0.80 (95%CI 0.62-0.98), and AUC of training and validation cohorts in the combined model were 0.88 (95%CI 0.81-0.96) and 0.81 (95%CI 0.62-0.99). Both the radiomics and the combined models have good prediction efficiency in the training and validation cohorts. Still, DeLong test shows that there is no difference between them.

Conclusions

Compared with the clinical model, the radiomics model and the combined model can better predict the disease progression of early-stage NSCLC after SABR, which might contribute to individualized follow-up plans and treatment strategies.

Photodynamic therapy to a primary cancer of the peripheral lung: Case report

Photodynamic therapy (PDT) is an FDA approved treatment for lung cancer. In the United States the photosensitizer porfimer sodium (Photofrin®, Pinnacle Biologics) is intravenously introduced at 2mg/kg. After approximately 48 h, illumination to activate the photosensitizer is initiated, with 630nm red light at 200J/cm, delivered by fiber-optic catheter, brought to the tumor endo- bronchially, and delivered for 500 s. This will create, in the presence of oxygen, a Type II Photodynamic Reaction (PDR) which generates singlet oxygen species that are tumor ablative. Classically, PDT for lung cancer has been employed for symptomatic central and obstructing tumors with great success. This case report describes an innovative approach to treat a peripheral, early stage lung cancer employing magnetic navigation and endobronchial treatment. We report on a 79 year old male with numerous comorbidities including pulmonary fibrosis, who was found to have a biopsy proven peripheral and solitary non-small cell cancer. Due to prior SBRT (stereotactic body radiation therapy) with dose levels causing radiation fibrosis, he was not a candidate for repeat SBRT, and he was not a surgical candidate due to comorbidities. Tumor control with PDT was achieved without treatment related morbidity. This report details our findings.

Rationale for Combing Stereotactic Body Radiation Therapy with Immune Checkpoint Inhibitors in Medically Inoperable Early-Stage Non-Small Cell Lung Cancer

Simple Summary

The rate of recurrence remains high for lymph node negative early-stage non-small cell lung cancer that are over 2–3 cm in size following stereotactic body radiation therapy (SBRT). This is due to the increased incidence of out-of-field failures, which warrants the addition of systemic therapy. Immune checkpoint inhibitors (ICIs), a class of immunotherapy, may induce a strong distant therapeutic effect known as the “abscopal” effect. This makes them a very suitable class of drugs to be combined with SBRT when treating early lung cancer with high-risk features, such as larger tumor size. In this review, we discuss the rationale and evidence for doing so.

Abstract

Stereotactic body radiation therapy (SBRT) has been widely adopted as an alternative to lobar resection in medically inoperable patients with lymph-node negative (N0) early-stage (ES) non-small cell lung cancer (NSCLC). Excellent in-field local control has been consistently achieved with SBRT in ES NSCLC ≤ 3 cm in size. However, the out-of-field control following SBRT remains suboptimal. The rate of recurrence, especially distant recurrence remains high for larger tumors. Additional systemic therapy is warranted in N0 ES NSCLC that is larger in size. Radiation has been shown to have immunomodulatory effects on cancer, which is most prominent with higher fractional doses. Strong synergistic effects are observed when immune checkpoint inhibitors (ICIs) are combined with radiation doses in SBRT’s dose range. Unlike chemotherapy, ICIs can potentiate a strong systemic response outside of the irradiated field when combined with SBRT. Together with their less toxic nature, ICIs represent a very suitable class of systemic agents to be combined with SBRT when treating ES NSCLC with high-risk features, such as larger tumor size. In this review, we describe the rationale and emerging evidence, as well as ongoing investigations in this area.

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.

Escalated Maximum Dose in the Planning Target Volume Improves Local Control in Stereotactic Body Radiation Therapy for T1-2 Lung Cancer

Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage lung cancer. The purpose of this study was to investigate the optimal dose distribution and prognostic factors for local control (LC) after SBRT for lung cancer. A total of 104 lung tumors from 100 patients who underwent SBRT using various treatment regimens were analyzed. Dose distributions were corrected to the biologically effective dose (BED). Clinical and dosimetric factors were tested for association with LC after SBRT. The median follow-up time was 23.8 months (range, 3.4-109.8 months) after SBRT. The 1- and 3-year LC rates were 95.7% and 87.7%, respectively. In univariate and multivariate analyses, pathologically confirmed squamous cell carcinoma (SQ), T2 tumor stage, and a Dmax < 125 Gy (BED10) were associated with worse LC. The LC rate was significantly lower in SQ than in non-SQ among tumors that received a Dmax < 125 Gy (BED10) (p = 0.016). However, there were no significant differences in LC rate between SQ and non-SQ among tumors receiving a Dmax ≥ 125 Gy (BED10) (p = 0.198). To conclude, SQ, T2 stage, and a Dmax < 125 Gy (BED10) were associated with poorer LC. LC may be improved by a higher Dmax of the planning target volume.

Identification of novel prognostic factors focusing on clinical outcomes in patients with non-small cell lung cancer after stereotactic body radiotherapy

Stereotactic body radiotherapy (SBRT) has attracted extensive attention as an effective treatment for patients with early-stage non-small cell lung cancer. However, the factors affecting prognosis after SBRT have not been fully elucidated. The aim of the present study was to investigate the prognostic factors associated with overall survival (OS) and local control (LC) after SBRT. Between March 2003 and March 2020, 497 patients with primary or oligo-metastatic lung cancer who underwent SBRT treatment were retrospectively reviewed. Univariate analysis was performed against various factors related to patient and tumor characteristics using Kaplan-Meier method. Furthermore, the factors with statistically significant differences identified via univariate analysis underwent a stratified Cox proportional hazard regression analysis. The median follow-up period for all patients was 26.17 months (range, 0.36-194.37), and the 5-year OS and LC rates were 66.3 and 86.0%, respectively. Multivariate analysis showed that surfactant protein-D (SP-D), tumor CT values (TCTV) and iodine density values (IDV) were independent prognostic factors for OS, and histology, TCTV and IDV were for LC. Although histology was not selected as a prognostic factor related to OS, it was indicated that patients with squamous cell carcinoma were associated with the SP-D high group compared with the SP-D normal group. In addition, TCTV was correlated to water density values, which tended to decrease with increasing IDV. From these findings, SP-D and TCTV were identified as potential new candidate prognostic factors after SBRT, and it is possible that combining SP-D and histology, and TCTV and IDV may improve the accuracy of prognostic prediction.

The markerless lung target tracking AAPM Grand Challenge (MATCH) results

PURPOSE

Lung stereotactic ablative body radiotherapy (SABR) is a radiation therapy success story with level 1 evidence demonstrating its efficacy. To provide real-time respiratory motion management for lung SABR, several commercial and preclinical markerless lung target tracking (MLTT) approaches have been developed. However, these approaches have yet to be benchmarked using a common measurement methodology. This knowledge gap motivated the MArkerless lung target Tracking CHallenge (MATCH). The aim was to localize lung targets accurately and precisely in a retrospective in silico study and a prospective experimental study.

METHODS

MATCH was an American Association of Physicists in Medicine sponsored Grand Challenge. Common materials for the in silico and experimental studies were the experiment setup including an anthropomorphic thorax phantom with two targets within the lungs, and a lung SABR planning protocol. The phantom was moved rigidly with patient-measured lung target motion traces, which also acted as ground truth motion. In the retrospective in silico study a volumetric modulated arc therapy treatment was simulated and a dataset consisting of treatment planning data and intra-treatment kilovoltage (kV) and megavoltage (MV) images for four blinded lung motion traces was provided to the participants. The participants used their MLTT approach to localize the moving target based on the dataset. In the experimental study, the participants received the phantom experiment setup and five patient-measured lung motion traces. The participants used their MLTT approach to localize the moving target during an experimental SABR phantom treatment. The challenge was open to any participant, and participants could complete either one or both parts of the challenge. For both the in silico and experimental studies the MLTT results were analyzed and ranked using the prospectively defined metric of the percentage of the tracked target position being within 2 mm of the ground truth.

RESULTS

A total of 30 institutions registered and 15 result submissions were received, four for the in silico study and 11 for the experimental study. The participating MLTT approaches were: Accuray CyberKnife (2), Accuray Radixact (2), BrainLab Vero, C-RAD, and preclinical MLTT (5) on a conventional linear accelerator (Varian TrueBeam). For the in silico study the percentage of the 3D tracking error within 2 mm ranged from 50% to 92%. For the experimental study, the percentage of the 3D tracking error within 2 mm ranged from 39% to 96%.

CONCLUSIONS

A common methodology for measuring the accuracy of MLTT approaches has been developed and used to benchmark preclinical and commercial approaches retrospectively and prospectively. Several MLTT approaches were able to track the target with sub-millimeter accuracy and precision. The study outcome paves the way for broader clinical implementation of MLTT. MATCH is live, with datasets and analysis software being available online at https://www.aapm.org/GrandChallenge/MATCH/ to support future research.

Stereotactic body radiotherapy for early-stage non-small cell lung cancer: a multicentre study by the Oncologic Group for the Study of Lung Cancer (Spanish Radiation Oncology Society)

PURPOSE/OBJECTIVE(S)

Stereotactic body radiotherapy (SBRT) has become the standard of care for patients with medically inoperable early-stage non-small cell lung cancer (NSCLC) and for patients who refuse surgery. The aim of this study was to evaluate the effectiveness and safety of primary SBRT in patients with early-stage NSCLC.

MATERIALS/METHODS

Retrospective multicenter study of 397 patients (416 primary lung tumours) treated with SBRT at 18 centres in Spain. 83.2% were men. The median age was 74.4 years. In 94.4% of cases, the tumour was inoperable. The pathological report was available in 54.6% of cases. SPSS vs 22.0. was used to perform all statistical analyses.

RESULTS

Complete response was obtained in 53.6% of cases. Significant prognostic factors were standard CT planning (p = 0.014) and 4D cone beam CT (p = 0.000). Acute and chronic toxicity ≥ grade 3 was observed in 1.2% of cases. At a median follow-up of 30 months, local relapse was 9.6%, lymph node relapse 12.8%, distant metastasis 16.6%, and another lung tumour 11.5%. Complete response was the only significant prognostic factor for local relapse (p = 0.012) and distant metastasis (p = 0.001). The local relapse-free survival was 88.7%. The overall survival was 75.7%. The cancer-specific survival was 92.7%. The disease-free survival was 78.7%.

CONCLUSION

SBRT is an effective and well-tolerated treatment option for patients with early-stage lung cancer who are not suitable for surgery. The most important prognostic factor for local and distant recurrence was complete response, which in our sample depended on the type of CT planning and the IGRT technique.

Adaptive MR-Guided Stereotactic Radiotherapy is Beneficial for Ablative Treatment of Lung Tumors in High-Risk Locations

PURPOSE

To explore the benefit of adaptive magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) for treatment of lung tumors in different locations with a focus on ultracentral lung tumors (ULT).

PATIENTS & METHODS

A prospective cohort of 21 patients with 23 primary and secondary lung tumors was analyzed. Tumors were located peripherally (N = 10), centrally (N = 2) and ultracentrally (N = 11, planning target volume (PTV) overlap with proximal bronchi, esophagus and/or pulmonary artery). All patients received MRgSBRT with gated dose delivery and risk-adapted fractionation. Before each fraction, the baseline plan was recalculated on the anatomy of the day (predicted plan). Plan adaptation was performed in 154/165 fractions (93.3%). Comparison of dose characteristics between predicted and adapted plans employed descriptive statistics and Bayesian linear multilevel models. The posterior distributions resulting from the Bayesian models are presented by the mean together with the corresponding 95% compatibility interval (CI).

RESULTS

Plan adaptation decreased the proportion of fractions with violated planning objectives from 94% (predicted plans) to 17% (adapted plans). In most cases, inadequate PTV coverage was remedied (predicted: 86%, adapted: 13%), corresponding to a moderate increase of PTV coverage (mean +6.3%, 95% CI: [5.3-7.4%]) and biologically effective PTV doses (BED₁₀) (BED_min: +9.0 Gy [6.7-11.3 Gy], BED_mean: +1.4 Gy [0.8-2.1 Gy]). This benefit was smaller in larger tumors (-0.1%/10 cm³ PTV [-0.2 to -0.02%/10 cm³ PTV]) and ULT (-2.0% [-3.1 to -0.9%]). Occurrence of exceeded maximum doses inside the PTV (predicted: 21%, adapted: 4%) and violations of OAR constraints (predicted: 12%, adapted: 1%, OR: 0.14 [0.04-0.44]) was effectively reduced. OAR constraint violations almost exclusively occurred if the PTV had touched the corresponding OAR in the baseline plan (18/19, 95%).

CONCLUSION

Adaptive MRgSBRT is highly recommendable for ablative treatment of lung tumors whose PTV initially contacts a sensitive OAR, such as ULT. Here, plan adaptation protects the OAR while maintaining best-possible PTV coverage.

4DCT and VMAT for lung patients with irregular breathing

PURPOSE

Irregular breathing in lung cancer patients is a common contra-indication to 4D computerized tomography (4DCT), which may then limit radiotherapy treatment options. For irregular breathers, we investigated whether 3DCT or 4DCT (1) better represents tumor motion, (2) better represents average tumor densities, and (3) better allows for volumetric modulated arc threarpy (VMAT) plans delivered with acceptable dosimetric accuracy.

METHODS

Ten clinical breathing traces were identified with irregularities in phase and amplitude, and fed to a programmable moving platform incorporating an anthropomorphic lung tumor phantom. 3DCT and 4DCT data resorted by phase (4DCT-P) and amplitude (4DCT-A) were acquired for each trace. Tumors were delineated by Hounsfield unit (HU) thresholding and apparent motion range assessed. HU profiles were extracted from each image and agreement with calculated expected profiles quantified using area-under-curve (AUC) scoring. Clinically representative VMAT plans were created for each image, delivered to the irregularly moving phantom, and measured with a small-volume ion chamber at the tumor center.

RESULTS

Median difference from expected tumor motion range for 3DCT, 4DCT-P, and 4DCT-A was 2.5 [1.6-3.6] cm, 1.1 [0.1-1.9] cm, and 1.3 [0.4-1.9] cm, respectively (p = 0.005, 4DCT-P vs. 3DCT). Median AUC scores (ideal = 0) for 3DCT, 4DCT-P, and 4DCT-A were 0.25 [0.14-0.49], 0.12 [0.05-0.42], and 0.13 [0.09-0.44], respectively (p = 0.005, 4DCT-P vs. 3DCT). Nine of ten 4DCT-P plans and all 4DCT-A plans measured within 2.5% of expected dose in the treatment planning system (TPS), compared with seven 3DCT plans.

CONCLUSION

For the cases studied tumor motion range and average density was better represented with 4DCT compared with 3DCT, even in the presence of irregular breathing. 4DCT images allowed for delivery of VMAT plans with acceptable dosimetric accuracy. No significant differences were detected between phase and amplitude resorting. In combination with 4D cone beam imaging at treatment, our findings have given us confidence to introduce 4DCT and VMAT for lung radiotherapy patients with irregular breathing.

Combining computed tomography and biologically effective dose in radiomics and deep learning improves prediction of tumor response to robotic lung stereotactic body radiation therapy

PURPOSE

The aim of this study is to improve the performance of machine learning (ML) models in predicting response of non-small cell lung cancer (NSCLC) to stereotactic body radiation therapy (SBRT) by integrating image features from pre-treatment computed tomography (CT) with features from the biologically effective dose (BED) distribution.

MATERIALS AND METHODS

Image features, consisting of crafted radiomic features or machine-learned features extracted using a convolutional neural network, were calculated from pre-treatment CT data and from dose distributions converted into BED for 80 NSCLC lesions over 76 patients treated with robotic guided SBRT. ML models using different combinations of features were trained to predict complete or partial response according to response criteria in solid tumors, including radiomics CT (Rad_CT ), radiomics CT and BED (Rad_CT,BED ), deep learning (DL) CT (DL_CT ), and DL CT and BED (DL_CT,BED ). Training of ML included feature selection by neighborhood component analysis followed by ensemble ML using robust boosting. A model was considered as acceptable when the sum of average sensitivity and specificity on test data in repeated cross validations was at least 1.5.

RESULTS

Complete or partial response occurred in 58 out of 80 lesions. The best models to predict the tumor response were those using BED variables, achieving significantly better area under curve (AUC) and accuracy than those using only features from CT, including a Rad_CT,BED model using three radiomic features from BED, which scored an accuracy of 0.799 (95% confidence intervals (0.75-0.85)) and AUC of 0.773 (0.688-0.846), and a DL_CT,BED model also using three variables with an accuracy of 0.798 (0.649-0.829) and AUC of 0.812 (0.755-0.867).

CONCLUSION

According to our results, the inclusion of BED features improves the response prediction of ML models for lung cancer patients undergoing SBRT, regardless of the use of radiomic or DL features.

Local ablative therapy in oncogenic-driven oligometastatic non-small cell lung cancer: present and ongoing strategies-a narrative review

Oligometastatic (OM) disease is defined by a low metastatic tumor spread. OM non-small cell lung cancer (NSCLC) treatment aims to improve the patient's prognosis and quality of life, in an attempt-to-cure objective. Oncogenic-driven metastatic NSCLC accounts for about 20-25% of NSCLCs, with an ever-increasing number of potentially druggable molecular alterations. Due to specific targeted therapy, the care and prognosis of mutated NSCLC is quite different from non-oncogenic-driven NSCLC. However, OM-NSCLC treatment guidelines do not specifically discuss oncogenic-driven OM-NSCLC patients. We conducted a narrative review regarding retrospective and prospective studies published from inception to May 2020 dealing with oncogenic-driven OM-NSCLC in order to: (I) describe the specific patterns of metastatic spread of oncogenic-driven NSCLC (i.e., bone and pleural tropism in EGFR mutated NSCLC and serous and brain metastases in ALK NSCLC); (II) review the low level of current evidence for local ablative therapy (LAT) strategies in patients with oncogenic-driven OM-NSCLC, focusing on the benefit/risk of tyrosine kinase inhibitors (TKI) and LATs combination and (III) present strategies to help to select the best candidate for an attempt-to-cure approach. Finally, the optimal strategy may be to introduce a targeted therapy, then treat all tumor sites with LAT, and finally continue TKI for unknown prolonged duration in an attempt to prolong progression free survival in most patients, improve overall survival for some patients, and potentially lead to a cancer cure for a few patients.

Estimation of delivered dose to lung tumours considering setup uncertainties and breathing motion in a cohort of patients treated with stereotactic body radiation therapy

INTRODUCTION

Dose-response relationships for local control of lung tumours treated with stereotactic body radiotherapy (SBRT) have proved ambiguous, however, these have been based on the prescribed or planned dose. Delivered dose to the target may be a better predictor for local control. In this study, the probability of the delivered minimum dose to the clinical target volume (CTV) in relation to the prescribed dose was estimated for a cohort of patients, considering geometrical uncertainties.

MATERIALS AND METHODS

Delivered doses were retrospectively simulated for 50 patients treated with SBRT for lung tumours, comparing two image-guidance techniques: pre-treatment verification computed tomography (IG1) and online cone-beam computed tomography (IG2). The prescribed dose was typically to the 67% isodose line of the treatment plan. Simulations used in-house software that shifted the static planned dose according to a breathing motion and sampled setup/matching errors. Each treatment was repeatedly simulated, generating a multiplicity of dose-volume histograms (DVH). From these, tumour-specific and population-averaged statistics were derived.

RESULTS

For IG1, the probability that the minimum CTV dose (D_98%) exceeded 100% of the prescribed dose was 90%. With IG2, this probability increased to 99%.

CONCLUSIONS

Doses below the prescribed dose were delivered to a considerably larger part of the population prior to the introduction of online soft-tissue image-guidance. However, there is no clear evidence that this impacts local control, when compared to previous published data.

Prolonged overall treatment time negatively affects the outcomes of stereotactic body radiotherapy for early-stage non-small-cell lung cancer: A propensity score-weighted, single-center analysis

Previous studies have reported conflicting results for the effect of overall treatment time with stereotactic body radiotherapy on tumor control in early-stage non-small-cell lung cancer. To examine this effect, we conducted a propensity score-weighted, retrospective, observational study at a single institution. We analyzed the data of 200 patients with early-stage non-small-cell lung cancer who underwent stereotactic body radiotherapy (48 Gy in 4 fractions) at our institution between January 2007 and October 2013. Patients were grouped into consecutive (overall treatment time = 4–5 days, n = 116) or non-consecutive treatment groups (overall treatment time = 6–10 days, n = 84). The outcomes of interest were local control and overall survival. The Cox regression model was used with propensity score and inverse probability of treatment weighting. The median overall treatment times in the consecutive and non-consecutive groups were 4 and 6 days, respectively. The 5-year local control and overall survival rates in the consecutive vs. the non-consecutive group were 86.3 vs. 77.2% and 55.5 vs. 51.8%, respectively. After propensity score weighting, consecutive stereotactic body radiotherapy was associated with positive local control (adjusted hazard ratio 0.30, 95% confidence interval 0.14–0.65; p = 0.002) and overall survival (adjusted hazard ratio 0.56, 95% confidence interval 0.34–0.91; p = 0.019) benefits. The prolonged overall treatment time of stereotactic body radiotherapy treatment negatively affected the outcomes of patients with early-stage non-small-cell lung cancer. To our knowledge, this is the first study to show that in patients with early-stage non-small-cell lung cancer treated with the same dose-fractionation regimen, consecutive stereotactic body radiotherapy has a more beneficial effect on tumor control than non-consecutive stereotactic body radiotherapy.

Discontinuous stereotactic body radiotherapy schedule increases overall survival in early-stage non-small cell lung cancer

OBJECTIVES

The duration of stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC) may affect patient outcomes. We aimed to determine the impact of a continuous versus discontinuous SBRT schedule on local control (LC) and overall survival (OS) in NSCLC patients.

MATERIALS AND METHODS

Consecutive NSCLC stage I patients (475) treated with SBRT in four centers were retrospectively analyzed. The delivered dose ranged from 48 to 75 Gy in 3-10 fractions. Based on the ratio between the treatment duration (TD) and number of fractions (n), patients were divided into two groups: continuous schedule (CS) (TD ≤ 1.6n; 239 patients) and discontinuous schedule (DS) (TD > 1.6n; 236 patients). LC and OS were compared using Cox regression analyses after propensity score matching (216 pairs).

RESULTS

The median follow-up period was 41 months. Multivariate analysis showed that the DS (hazard ratio (HR): 0.42; 95 % confidence interval (CI): 0.22-0.78) and number of fractions (HR: 1.24; 95 % CI: 1.07-1.43) were significantly associated with LC. The DS (HR: 0.67; 95 % CI: 0.51-0.89), age (HR: 1.02; 95 % CI: 1-1.03), WHO performance status (HR: 2.27; 95 % CI: 1.39-3.7), and T stage (HR: 1.4; 95 % CI: 1.03-1.87) were significantly associated with OS. The 3-year LC and OS were 92 % and 64 % and 81 % and 53 % for DS and CS treatments, respectively (p < 0.01). Cox analysis confirmed that the discontinuous SBRT schedule significantly increased LC and OS.

CONCLUSION

DS is associated with significantly improved LC and OS in early-stage NSCLC patients treated with SBRT.

Computed tomography guided interstitial percutaneous high-dose-rate brachytherapy in the management of lung malignancies. A review of the literature

A growing number of patients with lung cancer are not amenable to surgery due to their age or comorbidities. For this reason, local ablative techniques have gained increasing interest recently in the management of inoperable lung tumors. High-dose-rate percutaneous interstitial brachytherapy, performed under CT-guidance, is a newer form of brachytherapy and is a highly conformal radiotherapy technique. The aim of this study was to describe this method and review the existing literature. Eight articles comprising 234 patients reported toxicity and clinical outcome. The follow-up ranged from 6 to 28 months. Diverse fractionation schemes were reported, with 20 Gy in a single fraction being the most frequently utilized. Toxicity was limited; major pneumothoraces occurred after only 8% of the interventions. Local control rates at one year ranged between 37% and 91%. In conclusion, high-dose-rate percutaneous interstitial brachytherapy is a safe, fast, and efficient treatment option for inoperable lung tumors.

Benefit of replanning in MR-guided online adaptive radiation therapy in the treatment of liver metastasis

PURPOSE

To assess the effects of daily adaptive MR-guided replanning in stereotactic body radiation therapy (SBRT) of liver metastases based on a patient individual longitudinal dosimetric analysis.

METHODS

Fifteen patients assigned to SBRT for oligometastatic liver metastases underwent daily MR-guided target localization and on-table treatment plan re-optimization. Gross tumor volume (GTV) and organs at risk (OARs) were adapted to the anatomy-of-the-day. A reoptimized plan (RP) and a rigidly shifted baseline plan (sBP) without re-optimization were generated for each fraction. After extraction of DVH parameters for GTV, planning target volume (PTV), and OARs (stomach, duodenum, bowel, liver, heart) plans were compared on a per-patient basis.

RESULTS

Median pre-treatment GTV and PTV were 14.9 cc (interquartile range (IQR): 7.7-32.9) and 62.7 cc (IQR: 42.4-105.5) respectively. SBRT with RP improved PTV coverage (V100%) for 47/75 of the fractions and reduced doses to the most proximal OARs (D1cc, Dmean) in 33/75 fractions compared to sBP. RP significantly improved PTV coverage (V100%) for metastases within close proximity to an OAR by 4.0% (≤ 0.2 cm distance from the edge of the PTV to the edge of the OAR; n = 7; p = 0.01), but only by 0.2% for metastases farther away from OAR (> 2 cm distance; n = 7; p = 0.37). No acute grade 3 treatment-related toxicities were observed.

CONCLUSIONS

MR-guided online replanning SBRT improved target coverage and OAR sparing for liver metastases with a distance from the edge of the PTV to the nearest luminal OAR < 2 cm. Only marginal improvements in target coverage were observed for target distant to critical OARs, indicating that these patients do not benefit from daily adaptive replanning.

Local Control After Stereotactic Body Radiation Therapy for Stage I Non-Small Cell Lung Cancer

PURPOSE

Numerous dose and fractionation schedules have been used to treat medically inoperable stage I non-small cell lung cancer (NSCLC) with stereotactic body radiation therapy (SBRT) or stereotactic ablative radiation therapy. We evaluated published experiences with SBRT to determine local control (LC) rates as a function of SBRT dose.

METHODS AND MATERIALS

One hundred sixty published articles reporting LC rates after SBRT for stage I NSCLC were identified. Quality of the series was assessed by evaluating the number of patients in the study, homogeneity of the dose regimen, length of follow-up time, and reporting of LC. Clinical data including 1, 2, 3, and 5-year tumor control probabilities for stages T1, T2, and combined T1 and T2 as a function of the biological effective dose were fitted to the linear quadratic, universal survival curve, and regrowth models.

RESULTS

Forty-six studies met inclusion criteria. As measured by the goodness of fit χ2/ndf, with ndf as the number of degrees of freedom, none of the models were ideal fits for the data. Of the 3 models, the regrowth model provides the best fit to the clinical data. For the regrowth model, the fitting yielded an α-to-β ratio of approximately 25 Gy for T1 tumors, 19 Gy for T2 tumors, and 21 Gy for T1 and T2 combined. To achieve the maximal LC rate, the predicted physical dose schemes when prescribed at the periphery of the planning target volume are 43 ± 1 Gy in 3 fractions, 47 ± 1 Gy in 4 fractions, and 50 ± 1 Gy in 5 fractions for combined T1 and T2 tumors.

CONCLUSIONS

Early-stage NSCLC is radioresponsive when treated with SBRT or stereotactic ablative radiation therapy. A steep dose-response relationship exists with high rates of durable LC when physical doses of 43-50 Gy are delivered in 3 to 5 fractions.

Higher biologically effective dose is associated with improved survival in patients with squamous cell carcinoma of the lung treated with stereotactic body radiation therapy

BACKGROUND

Multiple studies have suggested that patients with early-stage SCC of the lung treated with SBRT are more susceptible to local failure compared to other NSCLC histologies. It is unknown if higher BED leads to improved outcomes in this patient population. We evaluated the effect of "high" BED versus "low" BED SBRT on overall survival (OS) in SCC and non-SCC NSCLC patients.

METHODS

The National Cancer Database was used to identify patients with cT1-2N0M0 NSCLC diagnosed between 2006-2016 treated with 3-5 fraction SBRT. Patients were grouped by BED_high (>150 Gy) and BED_low (≤132 Gy). Univariate and multivariable analysis using Kaplan-Meier and Cox proportional hazards regression modeling were performed. Propensity-score matched analysis with inverse probability of treatment (IPTW) weighting was used to account for selection bias.

RESULTS

We identified 4,717 eligible SCC patients and 8,807 eligible non-SCC NSCLC patients. In SCC patients, BED_high was associated with improved OS in both univariate and multivariate analysis (MVA HR 0.84 95% CI 0.76-0.92, p < 0.001), with estimated IPTW-adjusted 3-year OS of 49% compared to 41% for the BED_low group. In contrast, BED_high was not associated with improved OS compared to BED_low for non-SCC NSCLC patients (MVA HR 0.94 95% CI 0.86-1.04, p = 0.23), with estimated IPTW-adjusted 3-year OS of 54% and 53%, respectively.

CONCLUSIONS

Our analysis suggests that in patients with early-stage NSCLC, SBRT regimens with BED > 150 Gy may confer a survival benefit in patients with SCC histology. Histology-based dose modification should be considered, and prospective validation may be warranted.

Stereotactic Body Radiation Therapy With a High Maximum Dose Improves Local Control, Cancer-Specific Death, and Overall Survival in Peripheral Early-Stage Non-Small Cell Lung Cancer

PURPOSE

We investigated whether delivery of a high biologically effective dose (BED) to primary tumors affects systemic outcomes of cancer-specific death (CSD) and overall survival (OS) rates after stereotactic body radiation therapy (SBRT) in patients with early-stage non-small cell lung cancer (ES-NSCLC).

METHODS AND MATERIALS

Among consecutive ES-NSCLC patients treated with SBRT between 2005 and 2019, we retrospectively identified patients who received a prescription of 50 to 60 Gy in 5 fractions with maximum doses of 62.5 to 100 Gy. Patients were categorized by maximum BED within the planning target volume with a threshold dose of 200 Gy. Outcomes were analyzed in all and matched patients.

RESULTS

Overall, 433 patients were eligible, and 262 and 171 patients were categorized into HighBED and LowBED groups, respectively. After propensity score matching, pairs of 154 patients were selected. Median follow-up times for the HighBED and LowBED groups were 52.3 months (range, 0.8-107.2 months) and 121.6 months (range, 3.0-162.8 months), respectively. The local recurrence rate in the HighBED group was significantly lower than that in the LowBED group (5-year rate, 1.3% and 7.2%; hazard ratio [HR], 0.15; 95% confidence interval [CI], 0.03-0.65; P = .011). Rates of any recurrence and CSD in the HighBED group were significantly lower (5-year any recurrence: 18.1% and 32.1%; HR, 0.52; 95% CI, 0.33-0.83; P = .0058; 5-year CSD: 9.5% and 21.8%; HR, 0.38; 95% CI, 0.20-0.70; P = .002), and OS in the HighBED group was significantly better compared with the LowBED group (5-year rate: 61.7% and 51.8%; HR, 0.71; 95% CI, 0.50-1.00; P = .047).

CONCLUSION

In patients with peripheral ES-NSCLC, SBRT with a high maximum dose may improve not only local control, but also any recurrence, CSD, and OS rates without increased toxicity. Further trials designed to evaluate whether higher intensity SBRT increases local control rates and contributes to improved CSD and OS outcomes are anticipated.

Impact of target dose inhomogeneity on BED and EUD in lung SBRT

PURPOSE

To evaluate the effect of dose heterogeneity in the treatment target on biologically effective dose (BED) for frequently used hypofractionation regimens in stereotactic body radiation therapy (SBRT).

METHODS

In the case of non-uniform target dose, BED in the planning target volume (PTV) is determined by using the linear-quadratic model. An expression for BED is obtained for an arbitrary dose distribution in the PTV in the case of small variance of the target dose. Another analytical expression for BED is obtained by assuming a Gaussian dose distribution in the target.

RESULTS

Analytical expressions for BED as a function of the variance of the target dose have been derived. It is shown that a relatively small dose inhomogeneity (<5%-6%) can cause a significant reduction (i.e. >10%) in the corresponding BED and equivalent uniform dose (EUD) compared to the case of uniform target dose.

CONCLUSIONS

Small variations in the absorbed dose can significantly reduce BED and EUD in the PTV. The effect of dose non-uniformity on BED increases with increasing dose per fraction. The observed reduction in BED compared to that for uniform target dose can be several times greater for SBRT than for standard fractionation with dose per fraction varying between 1.8 and 2 Gy.

A narrative review of invasive diagnostics and treatment of early lung cancer

The diagnosis and treatment of early-stage lung cancer remains a clinical challenge. The broadening implementation of lung cancer screening has resulted in positive findings in numerous patients that are mostly non-malignant. Many other patients have indeterminate nodules that are difficult to assess through simple observation. The critical interpretation of such screening results remains a challenge for radiologists and multidisciplinary teams involved in screening for lung cancer. The evaluation and diagnosis of each participant suspected for malignancy should be based on the basic clinical principles such as a carefully collected medical history, physical examination, and detailed analysis of all imaging tests performed. Indeed, the decision to go ahead with more invasive diagnostics requires consideration of the both the risks and benefits, with reflection upon the complete clinical and radiological picture. Although transthoracic needle aspiration biopsy remains the first-choice method of diagnosis, several newer technologies have slowly begun to emerge as potential replacements. The guiding strategy for method selection is to choose the least harmful approach that offers the most relevant potential insights. Transthoracic biopsy is an effective method that allows the collection of cytological and tissue material from small, peripheral tumors, but it carries a moderate risk of complications. Bronchofiberoscopy, especially in combination with electromagnetic navigation, fluoroscopy or radial EBUS, also allows effective diagnosis of the peripheral pulmonary nodules. One of the most important diagnostic methods is the EBUS examination, which allows determining of staging in addition to diagnosis. Anatomical lung lobe resection and lymphadenectomy or sampling of the hilar and mediastinal lymph nodes is currently the treatment of choice for patients with stage I and II non-small cell lung cancer (NSCLC), but sublobar resections are recommended when a patient has limited pulmonary function or other significant comorbidities. Notably, several studies have highlighted the potential utility of more limited resections in small malignant lesions less than 2cm in diameter, with pure AIS histology, when more than 50% of the diameter of pulmonary nodule has ground-glass opacity (GGO) attenuation on CT, or long volume doubling time (VDT). Videothoracoscopy is the preferred surgical approach for resection of early-stage lung cancer. Patients who are not candidates for surgery or do not agree to surgery can be offered radical radiotherapy. Stereotactic body radiation therapy (SBRT) is a type of radical radiotherapy with proven effectiveness, a high rate of local control and an acceptable risk of the development of later complications. Future trials are expected to define the role of SBRT in the treatment of early lung cancer in healthy subjects.

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.

Ten-Year Experience of Stereotactic Body Radiotherapy at a Single Institution: Impact of Technological Development on the Outcome of Patients With Early Lung Cancer

Purpose:

Advanced radiotherapeutic techniques and apparatus have been developed and widely applied in stereotactic body radiation therapy for early-stage non-small cell lung cancer, but their clinical benefits have not necessarily been confirmed. This study was performed to review our 10-year experience with therapy for the disease and to evaluate whether the advanced radiotherapeutic system implemented in our hospital 5 years after we began the therapy improved the clinical outcomes of patients.

Materials and Methods:

Patients who underwent the therapy at our hospital between April 2008 and March 2018 were retrospectively reviewed. They were divided into 2 groups treated with the conventional system or the advanced system, and the characteristics and clinical outcomes were compared between the groups. The same analyses were also performed in propensity-matched patients from the 2 groups.

Results:

Among the 73 patients eligible for this study, 42 were treated with the conventional system and 31 with the advanced system. All were treated as planned, and severe adverse events were rare. The local progression-free survival rate in the advanced system group was significantly higher than in the conventional system group (P = 0.025). In the propensity-matched patients, both the local progression-free survival rate and the overall survival rate were significantly higher compared in the advanced system group than the conventional system group (P = 0.089 and 0.080, respectively).

Conclusion:

The advanced system improved the outcomes of patients with the disease, suggesting that technological development has had a strong impact on clinical outcomes.

Recursive Partitioning Analysis for Local Control Achieved With Stereotactic Body Radiation Therapy for the Liver, Spine, or Lymph Nodes

Purpose

This study aims to develop a local control risk stratification using recursive partitioning analysis (RPA) for patients receiving stereotactic body radiation therapy (SBRT) for metastatic cancer.

Methods and Materials

A single institutional database of 397 SBRT treatments to the liver, spine, and lymph nodes was constructed. All treatments required imaging follow-up to assess for local control. Cox proportional hazards analysis was implemented before the decision tree analysis. The data were split into training (70%), validation (10%), and testing (20%) sets for RPA to optimize the training set.

Results

In the study, 361 treatments were included in the local control analysis. Two-year local control was 71%. A decision tree analysis was used and the resulting model demonstrated 93.10% fidelity for the validation set and 87.67% for the test set. RPA class 3 was composed of patients with non-small cell lung cancer (NSCLC) primary tumors and treatment targets other than the cervical, thoracic, and lumbar spines. RPA class 2 included patients with primary cancers other than NSCLC or breast and treatments targets of the sacral spine or liver. RPA class 1 consisted of all other patients (including lymph node targets and patients with primary breast cancer). Classes 3, 2, and 1 demonstrated 3-year local controls rates of 29%, 50%, and 83%, respectively. On subgroup analysis using the Kaplan-Meier method, treatments for lymph nodes and primary ovarian disease demonstrated improved local control relative to other treatment targets (P < .005) and primary disease sites (P < .005), respectively.

Conclusions

A local control risk stratification model for SBRT to sites of metastatic disease was developed. Treatment target and primary tumor were identified as critical factors determining local control. NSCLC primary lesions have increased local failure for targets other than the cervical, thoracic, or lumbar spines, and improved local control was identified for lymph node sites and breast or ovarian primary tumors.

Impact of Sarcopenia on Survival in Patients With Early-Stage Lung Cancer Treated With Stereotactic Body Radiation Therapy

Background

Sarcopenia has been associated with poor survival among cancer patients. Normalized total psoas area (NTPA) has been used as a surrogate for defining sarcopenia. Few data exist characterizing the impact of sarcopenia and other metrics of fitness on clinical outcomes in patients with early-stage non-small cell lung cancer (NSCLC) treated non-invasively with stereotactic body radiotherapy (SBRT).

Methods

To assess the association between sarcopenia and clinical outcomes, we conducted a retrospective analysis of consecutive patients treated with SBRT from 2013 to 2019 . Overall survival (OS), local failure free survival (LFS), distant failure free survival (DFS), NTPA, body mass index (BMI), and Charlson comorbidity index (CCI) were included for analysis. NTPA was calculated by measuring the psoas volume at the L3 vertebra and normalizing for patient height and gender. Survival functions were evaluated using the Kaplan-Meier method. Log-rank test and Cox-proportional hazards were performed for categorical and continuous variables, respectively. Significance was set as p < 0.05.

Results

A total of 91 patients met the criteria. The median age was seven years and Karnofsky Performance Status score (KPS) was 80 (range: 60-100). Approximately 79% of patients had T1 tumors. Median radiation dose and number of fractions were 60 Gy (range: 45-60) and 5 fractions (range: 3-5). Median NTPA was 531.16 mm²/m² (range: 90.4-1356.2). After normalization (sarcopenia: <385 mm²/m², female; <585 mm²/m^2, male), 39 patients (42.8%) had sarcopenia. NTPA had no association with OS (p = 0.7), LFS (p = 0.9), or DFS (p = 0.5). Increasing BMI was associated with improved OS (HR 0.90, 95% CI 0.83-0.98). With a median follow-up of 23.4 months, median OS was 60, 60, and 45.9 months (p = 0.37) in all patients, non-sarcopenic patients, and sarcopenic patients, respectively.

Conclusion

Sarcopenia was not associated with OS, LFS, or DFS. Increasing BMI is associated with improved OS. Future, prospective work is needed to define the impact of sarcopenia and other fitness metrics on clinical outcomes among NSCLC patients treated non-invasively with SBRT.

Correlating Dose Variables with Local Tumor Control in Stereotactic Body Radiation Therapy for Early-Stage Non-Small Cell Lung Cancer: A Modeling Study on 1500 Individual Treatments

BACKGROUND

Large variation regarding prescription and dose inhomogeneity exists in stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer. The aim of this modeling study was to identify which dose metric correlates best with local tumor control probability to make recommendations regarding SBRT prescription.

METHODS AND MATERIALS

We combined 2 retrospective databases of patients with non-small cell lung cancer, yielding 1500 SBRT treatments for analysis. Three dose parameters were converted to biologically effective doses (BEDs): (1) the (near-minimum) dose prescribed to the planning target volume (PTV) periphery (yielding BEDmin); (2) the (near-maximum) dose absorbed by 1% of the PTV (yielding BEDmax); and (3) the average between near-minimum and near-maximum doses (yielding BEDave). These BED parameters were then correlated to the risk of local recurrence through Cox regression. Furthermore, BED-based prediction of local recurrence was attempted by logistic regression and fast and frugal trees. Models were compared using the Akaike information criterion.

RESULTS

There were 1500 treatments in 1434 patients; 117 tumors recurred locally. Actuarial local control rates at 12 and 36 months were 96.8% (95% confidence interval, 95.8%-97.8%) and 89.0% (87.0%-91.1%), respectively. In univariable Cox regression, BEDave was the best predictor of risk of local recurrence, and a model based on BEDmin had substantially less evidential support. In univariable logistic regression, the model based on BEDave also performed best. Multivariable classification using fast and frugal trees revealed BEDmax to be the most important predictor, followed by BEDave.

CONCLUSIONS

BEDave was generally better correlated with tumor control probability than either BEDmax or BEDmin. Because the average between near-minimum and near-maximum doses was highly correlated to the mean gross tumor volume dose, the latter may be used as a prescription target. More emphasis could be placed on achieving sufficiently high mean doses within the gross tumor volume rather than the PTV covering dose, a concept needing further validation.

Image guidance in radiation therapy for better cure of cancer

The key goal and main challenge of radiation therapy is the elimination of tumors without any concurring damages of the surrounding healthy tissues and organs. Radiation doses required to achieve sufficient cancer-cell kill exceed in most clinical situations the dose that can be tolerated by the healthy tissues, especially when large parts of the affected organ are irradiated. High-precision radiation oncology aims at optimizing tumor coverage, while sparing normal tissues. Medical imaging during the preparation phase, as well as in the treatment room for localization of the tumor and directing the beam, referred to as image-guided radiotherapy (IGRT), is the cornerstone of precision radiation oncology. Sophisticated high-resolution real-time IGRT using X-rays, computer tomography, magnetic resonance imaging, or ultrasound, enables delivery of high radiation doses to tumors without significant damage of healthy organs. IGRT is the most convincing success story of radiation oncology over the last decades, and it remains a major driving force of innovation, contributing to the development of personalized oncology, for example, through the use of real-time imaging biomarkers for individualized dose delivery.

Effects of the recurrence pattern on patient survival following SABR for stage I lung cancer

Background: Information on the effect of the recurrence pattern on survival for stage I lung cancer following stereotactic ablative radiotherapy (SABR) is limited.Materials and Methods: The recurrence pattern was analyzed for 100 consecutive stage I non-small-cell lung cancer patients treated with SABR using predominantly 12 Gy × 4. Recurrences were classified as local, regional lymph nodes and distant. Distant recurrences included recurrences in the lung and outside the chest. Single lung recurrences were named solitary, if no other location was involved. Kaplan-Meier survival estimates were calculated for different locations of recurrence. Clinical and dosimetrical factors affecting survival were also analyzed.Results: Median follow-up was 32 months (3-123), median age 70 years (49-95). In total, 31 patients had recurrences after a median 21 months (4-60): 5 local; 10 regional; 8 distant outside the chest; 25 non-local lung recurrences, of which 15 were single - 10 of which solitary - and 10 multiple lung nodules. Patients with a solitary lung recurrence had longer survival compared to local or distant recurrences (p = .04 each), and compared to multiple lung nodules (p = .09). 3-year local recurrence-free survival was 92%, disease-free survival 69% and overall survival 59%. On multivariate analysis, disease-free survival was associated with statin use (p = .038) and tumor location (p = .035). Smoking history predicted overall survival (p < .0006).Conclusions: A total of 81% of recurrences involved the lungs. Patients with solitary lung recurrences/second primary lung cancers had the longest overall survival suggesting definitive treatment should be considered. The effects of statin use need to be explored further.

Stereotactic Image Guided Lung Radiation Therapy for Clinical Early Stage Non-Small Cell Lung Cancer: A Long-Term Report From a Multi-Institutional Database of Patients Treated With or Without a Pathologic Diagnosis

PURPOSE

Early stage lung cancer is treated with stereotactic body radiation therapy (SBRT) in patients who are unable or unwilling to undergo surgical resection. Some patients' comorbidities are so severe that they are unable to even undergo a biopsy. A clinical diagnosis without biopsy before SBRT has been used, but there are limited data on its efficacy.

METHODS AND MATERIALS

Data on patients treated with SBRT for non-small cell lung cancer, with and without tissue confirmation, were collected from multiple institutions across Europe, Canada, and the United States. Patients with a minimum of 2 years of comprehensive follow up were selected for analysis. Treatment and patient characteristics were compared. Overall survival (OS), disease-free survival (DFS), cause-specific survival (CSS), and rates of local recurrence (LR), regional recurrence (RR), and distant metastasis (DM) were calculated and analyzed.

RESULTS

A total of 701 patients were identified, of which 67% had tissue confirmation of their tumors. The 3- and 5-year outcomes for OS, CSS, and DFS were 83.8%, 93.1%, 69%, and 60.6%, 86.7%, 45.5%, respectively. The rates for LR, RR, and DM at 3 and 5 years were 6.4%, 9.3%, 14.3%, and 10.5%, 14.3%, 19.7%, respectively. There were no statistically significant differences in survival outcomes or recurrences between the biopsy and no-biopsy cohorts.

CONCLUSIONS

SBRT for clinically diagnosed lung cancers is efficacious in appropriately selected patients, with similar outcomes as those with a pathologic diagnosis. Thorough clinical and radiographic evaluations in a multidisciplinary setting are critical to the management of these patients.

Radiotherapy in Lung Cancer: Current and Future Role

Lung cancer is divided into two subgroups concerning its natural course and treatment strategies as follows: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). In this review, for NSCLC, the role of stereotactic body radiation therapy (SBRT) in early-stage, chemoradiation in the locally advanced stage, post-operative radiotherapy for patients with high risk after surgery and radiotherapy for metastatic disease will be discussed. Also, for SCLC, the role and timing of thoracic irradiation and prophylactic cranial irradiation (PCI) for the limited and extensive stages will be discussed.

[Stereotactic radiotherapy of stage I non-small cell lung cancer. State of the art in 2019 and recommendations: Stereotaxy as an alternative to surgery?]

Stereotactic radiotherapy (or Stereotactic body radiotherapy [SBRT]) is a technique currently well established in the therapeutic arsenal for the management of bronchial cancers. It represents the standard treatment for inoperable patients or who refuses surgery. It is well tolerated, especially in elderly and frail patients, and the current issue is to define its indications in operated patients, based on retrospective and randomized trials comparing stereotactic radiotherapy and surgery, with results equivalents. This work analyzes in detail the different aspects of pulmonary stereotactic radiotherapy and suggests arguments that help in the therapeutic choice between surgery and stereotaxic irradiation. In all cases, the therapeutic decision must be discussed in a multidisciplinary consultation meeting, while informing the patient of the possible therapeutic options.

Should stereotactic body radiotherapy doses be adjusted according to tumor size in early-stage non-small-cell lung cancer? A systematic review and meta-analysis

Aim: Treatment schedules of stereotactic body radiotherapy (SBRT) for patients with early-stage non-small-cell lung cancer (NSCLC) are varied. The aim of this study was to clarify the optimal biologically effective dose (BED) for the treatment of stage I NSCLC. Methods: Research findings published after 1990 detailing the effects of SBRT on early-stage NSCLC patients were compiled from the Medline, Embase, Web of Science and Cochrane Library. For comparative analyses, two groups were divided into moderate BED (100-150 Gy) and high BED (BED ≥150 Gy). Results: Two moderate BED studies and four high BED studies were selected for analysis. The results from the analysis of four moderate and high groups suggest that the 2-year local control rate was significantly lower in moderate BED group than that of high BED group (p = 0.04). Subgroup analysis by tumor size was also conducted. For patients with Stage IA disease, no difference in overall survival (OS) was found. No statistically significant difference was achieved in the instance of Stage IB tumor; however, the 2-year OS showed a trend in favor of high BED (p = 0.08). The remaining two studies, comparing 106 Gy (Stage IA) to 120-132 Gy (Stage IB) treatment, indicated a significantly higher 3-year OS in the 106 Gy group than that of 120-132 Gy group (p = 0.009). Conclusion: In patients with early-stage NSCLC treated with SBRT, our analyses suggested that a moderate BED, especially 106 Gy, is sufficient for the treatment of Stage IA tumor; although a high BED conferred no significant benefit to OS for the treatment of Stage IB tumor, a higher local control rate was achieved. Further detailed studies should be performed to explore the optimal BED for the treatment of Stage IB tumor.

Stereotactic body radiation therapy with higher biologically effective dose is associated with improved survival in stage II non-small cell lung cancer

OBJECTIVES

The role of stereotactic body radiation therapy (SBRT) in treating stage II non-small cell lung cancer (NSCLC) remains unclear. This study evaluates SBRT dose prescription patterns and survival outcomes in Stage II NSCLC using the National Cancer Database (NCDB).

MATERIALS AND METHODS

Patients diagnosed with Stage II NSCLC and treated with SBRT between 2004-2013 were identified in NCDB. The biologically effective dose with α/β = 10 Gy (BED₁₀) was calculated. Overall survival (OS) was analyzed using the Kaplan-Meier method and Cox regression models.

RESULTS

Of 56,543 patients with Stage II NSCLC, 451 (0.8%) received SBRT. There were 360 patients (79.8%) with node-negative and 91 patients (20.2%) with node-positive disease. The most common prescriptions were 10 Gy x 5 (35.9%) and 12 Gy x 4 (19.3%). The mean and median BED₁₀ were 114.9 Gy and 105.6 Gy, respectively. With median follow-up of 19.3 months, overall median survival was 23.7 months. Median survival was 22.4 months for those treated with BED₁₀ < 114.9 Gy versus 31.5 months for BED₁₀ ≥ 114.9 Gy (p = 0.036). On multivariate analysis, BED₁₀ as a continuous variable (hazard ratio [HR] 0.991, p = 0.009) and ≥ 114.9 Gy (HR 0.63, p = 0.015) were associated with improved survival in node-negative patients. BED₁₀ as a continuous variable (HR 0.997, p = 0.465) and ≥ 114.9 Gy (HR 0.81, p = 0.546) were not significant factors for predicting survival in node-positive patients.

CONCLUSION

SBRT is infrequently utilized to treat Stage II NSCLC in the United States. Treatment with higher BED₁₀ was associated with improved survival, and the benefit was limited to patients with node-negative disease.

A current review of dose-escalated radiotherapy in locally advanced non-small cell lung cancer

Background The mainstay therapy for locally advanced non-small cell lung cancer is concurrent chemoradiotherapy. Loco-regional recurrence constitutes the predominant failure patterns. Previous studies confirmed the relationship between increased biological equivalent doses and improved overall survival. However, the large randomized phase III study, RTOG 0617, failed to demonstrate the benefit of dose-escalation to 74 Gy compared with 60 Gy by simply increasing fraction numbers. Conclusions Though effective dose-escalation methods have been explored, including altered fractionation, adapting individualized increments for different patients, and adopting new technologies and new equipment such as new radiation therapy, no consensus has been achieved yet.

Potential role of senescence in radiation-induced damage of the aged skeleton

Human aging-related changes are exacerbated in cases of disease and cancer, and conversely aging is a catalyst for the occurrence of disease and multimorbidity. For example, old age is the most significant risk factor for cancer and among people who suffer from cancer, >60% are above the age of 65. Oxidative stress and DNA damage, leading to genomic instability and telomere dysfunction, are prevalent in aging and radiation-induced damage and are major cellular events that lead to senescence. Human exposures from nuclear fallout, cosmic radiation and clinical radiotherapy (RT) are some common sources of irradiation that affect bone tissue. RT has been used to treat malignant tumors for over a century, but the effects of radiation damage on tumor-adjacent normal tissue has largely been overlooked. There is an increase in the percent survivorship among patients post-RT, and it is in older survivors where the deleterious synergy between aging and radiation exposure conspires to promote tissue deterioration and dysfunction which then negatively impacts their quality of life. Thus, an aging skeleton is already pre-disposed to architectural deterioration, which is further worsened by radiation-induced bone damage. Effects of senescence and the senescence associated secretory phenotype (SASP) have been implicated in age-associated bone loss, but their roles in radiation-associated bone damage are still elusive. RT is used in treatment for a variety of cancers and in different anatomical locations, the sequelae of which include long-term morbidity and lifelong discomfort. Therefore, consideration of the growing evidence that implicates the role of senescence in radiation-induced bone damage argues in favor of exploiting current senotherapeutic approaches as a possible prevention or treatment.