Use of Stereotactic Ablative Radiotherapy (SABR) in Non-Small Cell Lung Cancer Measuring More Than 5 cm

Stereotactic Body Radiation Therapy for Stage IIA to IIIA Inoperable Non-Small Cell Lung Cancer: A Phase 1 Dose-Escalation Trial

PURPOSE

Larger tumors are underrepresented in most prospective trials on stereotactic body radiation therapy (SBRT) for inoperable non-small cell lung cancer (NSCLC). We performed this phase 1 trial to specifically study the maximum tolerated dose (MTD) of SBRT for NSCLC >3 cm.

METHODS AND MATERIALS

A 3 + 3 dose-escalation design (cohort A) with an expansion cohort at the MTD (cohort B) was used. Patients with inoperable NSCLC >3 cm (T2-4) were eligible. Select ipsilateral hilar and single-station mediastinal nodes were permitted. The initial SBRT dose was 40 Gy in 5 fractions, with planned escalation to 50 and 60 Gy in 5 fractions. Adjuvant chemotherapy was mandatory for cohort A and optional for cohort B, but no patients in cohort B received chemotherapy. The primary endpoint was SBRT-related acute grade (G) 4+ or persistent G3 toxicities (Common Terminology Criteria for Adverse Events version 4.03). Secondary endpoints included local failure (LF), distant metastases, disease progression, and overall survival.

RESULTS

The median age was 80 years; tumor size was >3 cm and ≤5 cm in 20 (59%) and >5 cm in 14 patients (41%). In cohort A (n = 9), 3 patients treated to 50 Gy experienced G3 radiation pneumonitis (RP), thus defining the MTD. In the larger dose-expansion cohort B (n = 25), no radiation therapy-related G4+ toxicities and no G3 RP occurred; only 2 patients experienced G2 RP. The 2-year cumulative incidence of LF was 20.2%, distant failure was 34.7%, and disease progression was 54.4%. Two-year overall survival was 53%. A biologically effective dose (BED) <100 Gy was associated with higher LF (P = .006); advanced stage and higher neutrophil/lymphocyte ratio were associated with greater disease progression (both P = .004).

CONCLUSIONS

Fifty Gy in 5 fractions is the MTD for SBRT to tumors >3 cm. A higher BED is associated with fewer LFs even in larger tumors. Cohort B appears to have had less toxicity, possibly due to the omission of chemotherapy.

Evaluation of tumour motion and internal/external correlation in lung SABR

OBJECTIVE

This study aims to analyse lung tumour motion and to investigate the correlation between the internal tumour motion acquired from four-dimensional computed tomography (4DCT) and the motion of an external surrogate.

METHODS

A data set of 363 4DCT images was analysed. Tumours were classified based on their anatomical lobes. The recorded gross tumour volume (GTV) information included the centroid GTV motion in the superior-inferior, anteroposterior and left-right directions, and in three-dimensions (3D). For the internal/external correlation, the RPM surrogate breathing signals of 260 patients were analysed via an in-house script. The external motion was correlated with the 3D centroid motion, and the maximum tumour motion via Spearman's correlation. The effect of tumour volume on the amount of motion was evaluated.

RESULTS

The greatest 3D tumour amplitude was found for tumours located in the lower part of the lung, with a maximum of 26.7 mm. The Spearman's correlation of the internal 3D motion was weak in the upper (r = 0.21) and moderate in the middle (r = 0.51) and the lower (r = 0.52) lobes. There was no obvious difference in the correlation coefficients between the maximum tumour displacement and the centroid motion. No correlation was found between the tumour volume and the magnitude of motion.

CONCLUSION

Our results suggest that tumour location can be a good predictor of its motion. However, tumour size is a poor predictor of the motion.

ADVANCES IN KNOWLEDGE

This knowledge of the distribution of tumour motion throughout the thoracic regions will be valuable to research groups investigating the refinement of motion management strategies.

Re-evaluating the risk factors for radiation pneumonitis in the era of immunotherapy

As one of the common complications of radiotherapy, radiation pneumonia (RP) limits the prognosis of patients. Therefore, better identifying the high-risk factors that lead to RP is essential to effectively prevent its occurrence. However, as lung cancer treatment modalities are being replaced and the era of immunotherapy has arrived, literature that reviews the parameters and mode of radiotherapy, chemotherapy drugs, targeted drugs and current hot immune checkpoint inhibitors related to RP is lacking. This paper summarizes the risk factors for radiation pneumonia by retrieving and analysing previously published literature and the results of large clinical trials. The literature primarily included retrospective analyses, including clinical trials in different periods and a part of the literature review. A systematic literature search of Embase, PubMed, Web of Science, and Clinicaltrials.gov was performed for relevant publications up to 6 Dec. 2022. Search keywords include, but are not limited to, "radiation pneumonia", "pneumonia", "risk factors", "immunotherapy", etc. The factors related to RP in this paper include physical parameters of radiotherapy, including V₅, V₂₀, and MLD; chemoradiotherapy mode and chemotherapy drugs, including paclitaxel and gemcitabine; EGFR-TKI; ALK inhibitors; antiangiogenic drugs; immune drugs and the underlying disease of the patient. We also introduce the possible mechanism of RP. In the future, we hope that this article not only sounds the alarm for clinicians but also helps to identify a method that can effectively intervene and reduce the occurrence of RP, significantly improve the quality of life and prognosis of patients, and more effectively improve the therapeutic effect of radiation therapy.

New Frontiers in Colorectal Cancer Treatment Combining Nanotechnology with Photo- and Radiotherapy

Colorectal cancer is the third most common cancer worldwide. Despite recent advances in the treatment of this pathology, which include a personalized approach using radio- and chemotherapies in combination with advanced surgical techniques, it is imperative to enhance the performance of these treatments and decrease their detrimental side effects on patients' health. Nanomedicine is likely the pathway towards solving this challenge by enhancing both the therapeutic and diagnostic capabilities. In particular, plasmonic nanoparticles show remarkable potential due to their dual therapeutic functionalities as photothermal therapy agents and as radiosensitizers in radiotherapy. Their dual functionality, high biocompatibility, easy functionalization, and targeting capabilities make them potential agents for inducing efficient cancer cell death with minimal side effects. This review aims to identify the main challenges in the diagnosis and treatment of colorectal cancer. The heterogeneous nature of this cancer is also discussed from a single-cell point of view. The most relevant works in photo- and radiotherapy using nanotechnology-based therapies for colorectal cancer are addressed, ranging from in vitro studies (2D and 3D cell cultures) to in vivo studies and clinical trials. Although the results using nanoparticles as a photo- and radiosensitizers in photo- and radiotherapy are promising, preliminary studies showed that the possibility of combining both therapies must be explored to improve the treatment efficiency.

Outcomes Following SBRT vs. IMRT and 3DCRT for Older Patients with Stage IIA Node-Negative Non-Small Cell Lung Cancer > 5 cm

BACKGROUND

To describe outcomes and compare the effectiveness of stereotactic body radiotherapy (SBRT) versus 3-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT) in patients with stage IIA lymph node-negative (N0) non-small cell lung cancer (NSCLC) tumors > 5 cm.

METHODS

We used the SEER-Medicare database (2005-2015) to identify patients > 65 years with stage IIA (AJCC TNM7) N0 NSCLC > 5 cm tumors who were treated with SBRT, IMRT, and 3DCRT. We used propensity score methods with inverse probability weighting to compare lung cancer-specific survival (LCSS), overall survival (OS), and toxicity.

RESULTS

Of 584 patients, 88 (15%), 140 (24%), and 356 (61%) underwent SBRT, IMRT, and 3DCRT, respectively. The SBRT group was older (P = .004), had more comorbidities (P = .02), smaller tumors (P = .03), and more adenocarcinomas (P < .0001). We found a trend towards higher median unadjusted OS with SBRT compared to IMRT and 3DCRT (19 vs. 13 and 14 months, respectively, P = .37). In our propensity score-adjusted analyses, SBRT was significantly associated with better OS and LCSS compared to IMRT (HR_OS: 0.78, 95% CI: 0.68-0.89, HR_LCSS: 0.70, 95% CI: 0.60-0.81) and 3DCRT (HR_OS: 0.81, 95% CI: 0.72-0.93, HR_LCSS: 0.80, 95% CI: 0.68-0.93). SBRT-treated patients also had lower overall adjusted complication rates compared to IMRT (OR: 0.74, 95% CI: 0.55-0.99) and 3DCRT (OR: 0.53, 95% CI: 0.40-0.71).

CONCLUSION

For patients with NSCLC tumors > 5 cm, SBRT trends towards fewer toxicities and improved survival compared to other forms of radiotherapy. Our findings support SBRT as an appropriate treatment strategy for older patients with larger inoperable NSCLC tumors.

Stereotactic Ablative Radiotherapy in the Treatment of Early-Stage Lung Cancer - A Done Deal?

Stereotactic ablative radiotherapy (SABR) is an important curative-intent treatment option for early-stage non-small cell lung cancer. It offers good cancer control without invasive surgery and has become the standard of care for medically inoperable patients. The literature on SABR for early-stage non-small cell lung cancer is substantial and continues to grow. However, there remain areas of controversy where data are limited - notably the use of SABR in medically operable patients. Other areas of some debate include the treatment of central/ultra-central and large (>5 cm) lesions, as well as treatment with co-existing interstitial lung disease. This review article provides an overview of the current literature together with a discussion of future directions.

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.

Predicting personalised and progressive adaptive dose escalation to gross tumour volume using knowledge-based planning models for inoperable advanced-stage non-small cell lung cancer patients treated with volumetric modulated arc therapy

OBJECTIVES

Increased radiation doses could improve local control and overall survival of lung cancer patients, however, this could be challenging without exceeding organs at risk (OAR) dose constraints especially for patients with advanced-stage disease. Increasing OAR doses could reduce the therapeutic ratio and quality of life. It is therefore important to investigate methods to increase the dose to target volume without exceeding OAR dose constraints.

METHODS

Gross tumour volume (GTV) was contoured on synthetic computerised tomography (sCT) datasets produced using the Velocity adaptive radiotherapy software for eleven patients. The fractions where GTV volume decreased compared to that prior to radiotherapy (reference plan) were considered for personalised progressive dose escalation. The dose to the adapted GTV (GTVAdaptive) was increased until OAR doses were affected (as compared to the original clinical plan). Planning target volume (PTV) coverage was maintained for all plans. Doses were also escalated to the reference plan (GTVClinical) using the same method. Adapted, dose-escalated, plans were combined to estimate accumulated dose, D99 (dose to 99%) of GTVAdapted, PTV D99 and OAR doses and compared with those in the original clinical plans. Knowledge-based planning (KBP) model was developed to predict D99 of the adapted GTV with OAR doses and PTV coverage kept similar to the original clinical plans; prediction accuracy and model verification were performed using further data sets.

RESULTS

Compared to the original clinical plan, dose to GTV was significantly increased without exceeding OAR doses. Adaptive dose-escalation increased the average D99 to GTVAdaptive by 15.1Gy and 8.7Gy compared to the clinical plans. The KBP models were verified and demonstrated prediction accuracy of 0.4% and 0.7% respectively.

CONCLUSION

Progressive adaptive dose escalation can significantly increase the dose to GTV without increasing OAR doses or compromising dose to microscopic disease. This may increase overall survival without increasing toxicities.

Ultra-central lung tumors: safety and efficacy of protracted stereotactic body radiotherapy

BACKGROUND

For patients with early stage or medically inoperable lung cancer, stereotactic body radiotherapy (SBRT) is a general accepted and effective treatment option. The role of SBRT in ultra-central tumors remains controversial. The aim of this single-center retrospective analysis was to evaluate the safety and efficacy of protracted SBRT with 60 Gy in 12 fractions (with a biological effective dose (BED₁₀) of 90-150 Gy) for patients with ultra-central lung tumors.

MATERIALS AND METHODS

Patients with ultra-central lung tumors treated in our institution with 60 Gy in 12 fractions from January 2012 until April 2020 were included. Ultra-central tumors were defined as planning target volume (PTV) abutting or overlapping the main bronchi and/or trachea and/or esophagus. Data regarding patient-, tumor-, and treatment-related characteristics were evaluated.

RESULTS

A total of 72 patients met the criteria for ultra-central tumor location. The PTV abutted the main bronchus, trachea or esophagus in 79%, 22% and 28% of cases, respectively. At a median follow-up of 19 months, 1- and 2-year local control rates were 98% and 85%, respectively. Overall survival rates at 1 and 2 years were 77% and 52%, respectively. Grade 3 or higher toxicity was observed in 21%, of which 10 patients (14% of total) died of bronchopulmonary hemorrhage. A significant difference between patients with or without grade ≥3 toxicity was found for the mean dose (D_mean) to the main bronchus (p = 0.003), where a D_mean BED₃ of ≥91 Gy increased the risk of grade ≥3 toxicity significantly.

DISCUSSION

A protracted SBRT regimen of 60 Gy in 12 fractions for ultra-central lung tumors leads to high local control rates with toxicity rates similar to previous series, but with substantial risk of fatal bronchopulmonary hemorrhage. Therefore, possible risk factors of bronchopulmonary hemorrhage such as dose to the main bronchus should be taken into account.

Developments in radiation techniques for thoracic malignancies

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

Late Central Airway Toxicity after High-Dose Radiotherapy: Clinical Outcomes and a Proposed Bronchoscopic Classification

Simple Summary

High-dose radiotherapy is frequently used to treat lung cancer, however, it can cause serious central airway toxicity. Although radiation toxicity of the lung parenchyma has been studied extensively, relatively little has been published on bronchoscopic findings in the central airways and no standard classification/reporting system exists. With the growing use of high-dose (chemo)radiotherapy and high-dose hypo-fractionated radiotherapy in close proximity to central airways, as well as potential interactions with new systemic therapies, the risks and incidence of central airway toxicity may increase. In this retrospective study, we analyzed patient characteristics and clinical outcomes of 70 patients with central airway toxicity after high-dose radiotherapy. Furthermore, we analyzed the post-radiotherapy bronchoscopic images to identify main patterns of airway toxicity. We identified luminal stenosis and vascular changes as the two main patterns and have proposed a classification system. Preliminary analysis suggests that the pattern and severity of radiation toxicity may be of prognostic value.

Abstract

The study’s purpose was to identify the bronchoscopic patterns of central airway toxicity following high-dose radiotherapy or chemoradiotherapy, and to look at the consequences of these findings. Our institutional bronchoscopy database was accessed to identify main patterns of airway toxicity observed in a seven-year period. A total of 70 patients were identified with central airway toxicity, and the findings of bronchoscopy were used to derive a classification system. Patient characteristics, time from radiotherapy to toxicity, follow-up and survival were retrospectively analyzed. Results: The main bronchoscopic patterns of airway toxicity were vascular changes (telangiectasia, loss of vascularity, necrosis) and stenosis of the lumen (moderate, severe). Indications for bronchoscopy were airway symptoms (n = 28), assessment post-CRT/surgery (n = 12), (suspected) recurrence (n = 21) or assessment of radiological findings (n = 9). Stenosis was revealed by bronchoscopy at a median time of 10.0 months (IQR: 4–23.5) after radiotherapy and subsequent follow-up after identification was 23 months (IQR: 1.5–55). The corresponding findings for vascular changes were 29 months (IQR: 10.5–48.5), and follow-up after identification was nine months (IQR: 2.5–19.5). There was a statistically significant difference in survival rates between patients with necrosis and telangiectasia (p = 0.002) and loss of vascularity (p = 0.001). Eight out of 10 deceased patients with telangiectasia died of other causes and 4/8 patients with necrosis died of other causes. We identified two main patterns of central airway toxicity visualized with bronchoscopy after high-dose radiotherapy or chemoradiotherapy, and propose a bronchoscopic classification system based on these findings. Preliminary analysis suggests that the pattern and severity of radiation damage might be of prognostic value. Prospective data are required to confirm our findings.

Extending hypofractionated stereotactic body radiotherapy to tumours larger than 70cc - effects and side effects

BACKGROUND AND PURPOSE

Stereotactic body radiotherapy (SBRT) for tumours ≥5 cm is poorly studied and its utility and feasibility is uncertain. We here report the Karolinska experience of SBRT in this setting.

MATERIAL AND METHODS

All patients had a gross tumour volume (GTV) ≥70 cc, a prescribed physical dose of at least 40 Gy and received treatment between 1995-2012.

RESULTS

We included 164 patients with 175 tumours located in the thorax (n = 86), the liver (n = 27) and the abdomen (n = 62) and treated with a median prescribed dose (BED_α/β 10Gy) of 80 Gy (71.4-113). One- and 2- year local control rates were 82% and 61%. In multivariate analyses, minimum dose to the GTV and histological subtype were associated with local control. Renal cell carcinoma (RCC) histology showed the most favourable local control - 94% at 2 years for all histologies. Thirty-seven patients experienced grade 3-5 toxicity most likely related to SBRT. Seven of the ten patients with grade 5 toxicity, had a centrally located tumour in the thorax.

CONCLUSION

SBRT of tumours >5 cm in diameter may be an option for peripherally located lung and abdominal tumours. Histological origin and tumour location should be considered before treatment.

Stereotactic Ablative Radiation Therapy for Large (≥5 cm) Non-small Cell Lung Carcinoma

AIMS

Stereotactic ablative radiation therapy (SABR) is a standard of care for medically inoperable early stage non-small cell lung carcinoma. Tumours greater than 5 cm have been excluded from randomised trials using SABR and, hence, it is not used as a standard for larger lung tumours. However, improvements in radiation therapy techniques and the success of SABR in treatment of early stage disease may allow safe delivery of ablative doses to larger tumours. We analysed our experience with tumours ≥5 cm to determine the efficacy and toxicity profile of SABR in this setting.

MATERIALS AND METHODS

We evaluated survival, control rates, patterns of failure and toxicity in patients with a tumour diameter larger than 5 cm that had no nodal or distant metastases treated with SABR technology. Patients had been treated in two centres since 2009 and were retrospectively analysed. All patients had positron emission tomography staging, were discussed at a tumour board and were documented to have no nodal or distant metastatic disease. Treatment outcomes were analysed using Kaplan-Meier estimates and compared using the Log-rank test. Cox regression was used to investigate the association between the survival outcomes and predictor variables.

RESULTS

In total, 86 patients were identified. Six patients had no follow-up imaging. Therefore, 80 patients were available for analysis. All patients were reclassified according to the updated AJCC eighth edition. The median follow-up was 19.6 months. No patients received neoadjuvant or concurrent systemic therapy. One patient received adjuvant systemic therapy. The median age at treatment was 77 years (range 58-91). Eighty-four per cent were stage T3N0M0 and 16% were staged T4N0M0. The median tumour diameter was 5.8 cm (range 5.0-9.3 cm). The median gross tumour volume, measured on a single phase of the respiratory cycle, was 45.7 cm³ (range 12.1-203.3 cm³). The median overall survival was 20.9 months (95% confidence interval 12.6-29.1 months). One-, 2- and 3-year overall survival was 71%, 48% and 32%, respectively. The median local failure-free survival was 19.5 months (95% confidence interval 14.4-24.6). The median disease-free survival was 15.1 months (95% confidence interval 9.9-20.4 months). Local control at 1, 2 and 3 years was 85% (95% confidence interval 76-94%), 71% (95% confidence interval 58-84%) and 57% (95% confidence interval 40-74%), respectively. Forty-four patients (55%) had any treatment failure (local, mediastinal, intrapulmonary or distant metastases). Out-of-field intrapulmonary disease progression was the most common mode of failure, occurring in 21 patients (26%). Local failure occurred in 19 patients (24%) - alone or in combination with other progression. Distant metastases occurred in 20 patients (25%). Neither histological subtype, tumour size nor gross tumour volume had a statistically significant effect on local failure-free survival. Two patients experienced grade 3 late dyspnoea. There were no other reported grade 3 or higher acute or late toxicities.

CONCLUSION

SABR for larger lung tumours ≥5 cm results in high local control and acceptable survival in patients with medically inoperable large non-small cell lung carcinoma treated with radiation alone. Such patients should be considered for SABR owing to fewer treatment fractions and acceptable toxicity. Local control analysis reveals a sustained pattern of local failure emphasising the need for long-term follow-up. Improvements in technical strategies are required to further improve local control.

Immunomodulatory Effects of Radiotherapy

Radiation therapy (RT), an integral component of curative treatment for many malignancies, can be administered via an increasing array of techniques. In this review, we summarize the properties and application of different types of RT, specifically, conventional therapy with x-rays, stereotactic body RT, and proton and carbon particle therapies. We highlight how low-linear energy transfer (LET) radiation induces simple DNA lesions that are efficiently repaired by cells, whereas high-LET radiation causes complex DNA lesions that are difficult to repair and that ultimately enhance cancer cell killing. Additionally, we discuss the immunogenicity of radiation-induced tumor death, elucidate the molecular mechanisms by which radiation mounts innate and adaptive immune responses and explore strategies by which we can increase the efficacy of these mechanisms. Understanding the mechanisms by which RT modulates immune signaling and the key players involved in modulating the RT-mediated immune response will help to improve therapeutic efficacy and to identify novel immunomodulatory drugs that will benefit cancer patients undergoing targeted RT.

Sublobar resection for node-negative lung cancer 2-5 cm in size

OBJECTIVES

Sublobar resection (SLR) is an alternative to lobectomy for non-small-cell lung cancer (NSCLC). Outcomes following SLR for tumours >2 cm are not well described. We sought to determine the utilization of SLR for stage I tumours >2-5 cm in size and to determine predictors of outcome.

METHODS

We utilized the Surveillance, Epidemiology and End Results Program (SEER)-Medicare database to identify NSCLC patients with primary lung cancer ≥66 years old with stage I cancers >2-5 cm in size. We evaluated overall survival and cancer-specific survival among cohorts undergoing lobectomy versus SLR. Propensity score matching was performed. We compared patient characteristics and survival between groups.

RESULTS

For the study time period (2007-2012), among patients with tumours >2 cm and ≤5 cm (n = 4582), 3890 lobectomies (85%) and 692 SLR (15%) were performed. Patients undergoing SLR were older, had smaller tumours and more comorbidities. Patients undergoing lobectomy were much more likely to have any lymph nodes removed (95.6% vs 65.6%, P < 0.001) and to have >10 nodes removed (29.6% vs 7.5%, P < 0.001). All-cause mortality [hazard ratio (HR) 1.65, confidence interval (CI) 1.48-1.85] and cancer-specific (HR 1.63, CI 1.29-2.06) mortality were higher following SLR. At 3 years, overall survival (60.9%, CI 57.0-64.6% vs 54.4%, CI 50.4-58.2%) and cancer-specific survival (87.3%, CI 83.5-90.3% vs 76.5%, CI 71.0-81.1%) favoured lobectomy over SLR. In propensity-matched groups, both all-cause (HR 1.27, CI 1.10-1.47) and cancer-specific (HR 1.54, CI 1.11-2.16) mortality rates were higher with SLR.

CONCLUSIONS

In pathologically staged patients, SLR appears inferior to lobectomy for stage I NSCLC 2-5 cm in size. SLR is associated with less extensive lymphadenectomy and with worse survival than lobectomy in this cohort of patients. However, the 76.5% 3-year cancer-specific survival in patients undergoing SLR may exceed that of other localized treatment options for NSCLC. As such, SLR may be an appropriate option for high-risk patients with carefully staged 2-5 cm N0 tumours.

Reduced Fractionation in Lung Cancer Patients Treated with Curative-intent Radiotherapy during the COVID-19 Pandemic

Patients treated with curative-intent lung radiotherapy are in the group at highest risk of severe complications and death from COVID-19. There is therefore an urgent need to reduce the risks associated with multiple hospital visits and their anti-cancer treatment. One recommendation is to consider alternative dose-fractionation schedules or radiotherapy techniques. This would also increase radiotherapy service capacity for operable patients with stage I-III lung cancer, who might be unable to have surgery during the pandemic. Here we identify reduced-fractionation for curative-intent radiotherapy regimes in lung cancer, from a literature search carried out between 20/03/2020 and 30/03/2020 as well as published and unpublished audits of hypofractionated regimes from UK centres. Evidence, practical considerations and limitations are discussed for early-stage NSCLC, stage III NSCLC, early-stage and locally advanced SCLC. We recommend discussion of this guidance document with other specialist lung MDT members to disseminate the potential changes to radiotherapy practices that could be made to reduce pressure on other departments such as thoracic surgery. It is also a crucial part of the consent process to ensure that the risks and benefits of undergoing cancer treatment during the COVID-19 pandemic and the uncertainties surrounding toxicity from reduced fractionation have been adequately discussed with patients. Furthermore, centres should document all deviations from standard protocols, and we urge all colleagues, where possible, to join national/international data collection initiatives (such as COVID-RT Lung) aimed at recording the impact of the COVID-19 pandemic on lung cancer treatment and outcomes.

Engineering nanoparticles to reprogram radiotherapy and immunotherapy: recent advances and future challenges

Nanoparticles (NPs) have been increasingly studied for radiosensitization. The principle of NPs radio-enhancement is to use high-atomic number NPs (e.g. gold, hafnium, bismuth and gadolinium) or deliver radiosensitizing substances, such as cisplatin and selenium. Nowadays, cancer immunotherapy is emerged as a promising treatment and immune checkpoint regulation has a potential property to improve clinical outcomes in cancer immunotherapy. Furthermore, NPs have been served as an ideal platform for immunomodulator system delivery. Owing to enhanced permeability and retention (EPR) effect, modified-NPs increase the targeting and retention of antibodies in target cells. The purpose of this review is to highlight the latest progress of nanotechnology in radiotherapy (RT) and immunotherapy, as well as combining these three strategies in cancer treatment. Overall, nanomedicine as an effective strategy for RT can significantly enhance the outcome of immunotherapy response and might be beneficial for clinical transformation.

Fatal Radiation Pneumonitis: Literature Review and Case Series

Purpose

Fatal radiation pneumonitis is a rare event. In recent years, higher incidences of grade 5 pneumonitis have been reported. Based on 3 cases in our clinic, a literature review was performed to assess specific clinical features and risk factors for fatal pneumonitis.

Methods and Materials

Three patients with nonsmall cell lung cancer were treated with conventionally fractionated radiation therapy, 2 with volumetric modulated arc therapy and one with intensity modulated radiation therapy. All 3 patients had high volumes of 5 Gy in the total lung and contralateral lungs. Patients died of pneumonitis between 2 and 5 months after the end of radiation therapy. A literature review focused on grade 5 pneumonitis was performed for conventionally fractioned and stereotactic radiation therapy for lung cancer.

Results

Patients with grade 5 pneumonitis develop symptoms sooner than lower grade pneumonitis. Symptoms often do not respond to steroid treatment or return after steroid taper. Imaging features extend beyond the high dose area and involve the contralateral lung. Dosimetric risk factors include both low dose and high dose lung volumes. For patients undergoing stereotactic radiation therapy interstitial lung disease has been described as a risk factor.

Conclusions

Despite decades of investigating radiation pneumonitis, the question of the optimum dose distribution in the lung, a large dose to a small volume versus a small dose to a large volume, is still unresolved. When both low and high dose lung volume constraints are followed, the risk for grade 5 pneumonitis has been shown to be low even with intensity modulated radiation therapy and concurrent chemotherapy. In addition to dose factors, underlying clinical and radiographic parameters play an important role for the development of grade 5 pneumonitis.

Moderately Hypofractionated Radiotherapy Alone for Stage I-IIB Non-small Cell Lung Cancer

INTRODUCTION

The optimal management of patients with early non-small cell lung cancer (NSCLC) not amenable to surgical resection or stereotactic body radiotherapy (SBRT) or those with hilar nodal involvement ineligible for surgery or concurrent chemoradiotherapy is unclear. This report describes survival outcomes and toxicity profiles of patients treated with hypofractionated radiotherapy (HRT) alone.

METHODS

A total of 52 patients with Stage I-IIB NSCLC treated with HRT alone between 2010-2018 were reviewed. Patients were categorized as having ultracentral tumors if the planning target volume contacted or overlapped the proximal bronchial tree, esophagus, pulmonary vein or artery. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method and the competing risk cumulative incidence of locoregional failure (LRF) and distant failure (DF) were estimated using death without failure as a competing risk. Pneumonitis and esophagitis rates were evaluated as per Acute Common Terminology Criteria for Adverse Events (CTCAE) version 4.0.

RESULTS

Of the 52 patients analyzed, 50 patients were treated with radiotherapy alone to a dose of 70.2 Gy in 26 fractions, one patient was treated with 68 Gy in 25 fractions and one patient was treated with 65 Gy in 26 fractions. The median age was 72 (range 48-89), 42% of patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 2-3, 46% were stage I and 54% were stage II. Hilar nodal involvement was present in 21% of patients and 74% of node-negative patients had ultracentral primary tumors. Median OS was 39.6 months and the median PFS was 21.0 months. Overall three-year cumulative incidence of LRF and DF were 32% and 34%, respectively. Grade 3 pneumonitis occurred in two (4%) patients. No grade 3+ acute esophagitis or grade 4-5 toxicities were observed.

CONCLUSION

Hypofractionated thoracic radiotherapy consisting of 70.2 Gy is well-tolerated and results in favorable locoregional control for stage I-IIB patients who are not candidates for SBRT, surgery, or concurrent chemoradiotherapy.

Population-based patterns of treatment and survival for patients with stage I and II non-small cell lung cancer aged 65-74 years and 75 years or older

OBJECTIVES

Insights regarding utilization and survival of surgery and radiotherapy (stereotactic body radiotherapy (SBRT) or conventional radiotherapy (RT)) are lacking for older patients with stage I and II non-small cell lung cancer (NSCLC) in clinical practice.

METHODS

Data from the Netherlands Cancer Registry were retrieved for patients ≥65 years with clinical stage I-II NSCLC in 2010-2015. Descriptive analyses, overall survival (OS), and cox regression were stratified for stage I (n = 8742) and II (n = 3439) and compared age groups (65-74 years vs ≥75 years).

RESULTS

Patients aged 65-74 underwent surgery significantly more often compared to those aged ≥75 (stage I 55% vs 27%; stage II: 65% vs 35%), and received SBRT less often (I: 29% vs 42%; II: 5% vs 11%), conventional RT less often (I: 6% vs 11%; II 10% vs 24%) and best supportive care alone less often (BSC, I: 8% vs 19%; II: 9% vs 25%). One-year OS was significantly higher in patients aged 65-74 compared to those aged ≥75 (I: 87% vs 78%; II: 74% vs 60%); as was five-year OS (I: 49% vs 31%; II: 36% vs 18%). After adjustment for gender, histology, stage, treatment, and comorbidity, hazard ratio (HR) of death was higher for patients aged ≥75 compared to those aged 65-74 (I: HR 1.3, 95% confidence interval (CI) 1.1-1.5; II: HR 1.3 95%CI 1.1-1.7).

CONCLUSION

Patients aged ≥75 with stage I-II NSCLC had poorer OS, underwent surgery less often, and received SBRT, conventional RT, and BSC more often than patients aged 65-74. In both stages, one-year OS within age groups was similar for surgery and SBRT. However, long-term OS adjusted for prognostic factors was superior for surgery compared to SBRT and remained poorer for those aged ≥75. Prospective research should focus on predictive characteristics for treatment selection and patient-centered outcomes.

Knowledge-Based Planning for Identifying High-Risk Stereotactic Ablative Radiation Therapy Treatment Plans for Lung Tumors Larger Than 5 cm

PURPOSE

Stereotactic ablative body radiation therapy (SABR) for lung tumors ≥5 cm can be associated with more toxicity than that for smaller tumors. We investigated the relationship between dosimetry and toxicity and used a knowledge-based planning solution to retrospectively perform individualized treatment plan quality assurance (QA) with the aim of identifying where planning could have been improved.

METHODS AND MATERIALS

Previous retrospective analysis of 53 patients with primary or recurrent non-small cell lung cancer ≥5 cm, treated with 5- or 8-fraction volumetric modulated arc therapy SABR between 2008 and 2014, showed 30% with grade ≥3 toxicity. During this period, several improvements were made to departmental planning protocols. RapidPlan was used to compare dosimetry of patients with or without grade ≥3 toxicity. A model comprising plans from patients without toxicity and compliant with the current planning protocol was used to provide QA for the plans from patients who had toxicity.

RESULTS

Sixteen of 53 patients had grade ≥3 toxicity, including 10 with radiation pneumonitis (RP), 3 with lung hemorrhage (1 of these also had RP), and 1 with airway stenosis/atelectasis. RP was again shown to be significantly correlated with contralateral and total-lung V5 and mean lung dose. The 4 highest contralateral-lung doses belonged to patients with RP. Five of 10 clinical plans in patients with RP had a contralateral-lung mean dose up to 2.5 times higher than that of the knowledge-based plan. For 2 of 3 patients with lung hemorrhage and 1 with airway stenosis/atelectasis, the clinical plans had the highest proximal bronchial tree doses, which was also higher than in plans from the model. In 8 patients with grade ≥3 toxicity, clinical plans had dosimetry similar to that in the predictions from the model.

CONCLUSIONS

A "no-toxicity" RapidPlan model identified the potential for dosimetric improvement in nearly 50% of historical treatment plans from patients with grade ≥3 toxicity after SABR for lung tumors ≥5 cm. Model-based QA may be useful for benchmarking treatment planning protocols in routine practice and in clinical studies.

Stereotactic body radiotherapy (SBRT) for Stage I lung cancer

Stereotactic body radiation therapy (SBRT) is a newly developed technique currently in clinical use. SBRT originated from stereotactic radiosurgery (SRS) for intracranial tumors. Since the 1990s, SBRT has been widely used in clinical settings for the treatment of lung cancer. We review the history and current standard techniques. Previous clinical studies of lung cancer showed high local control rates with acceptable toxicities. Past and on-going clinical trials are also reviewed.

Phase 2 Study of Stereotactic Body Radiation Therapy and Stereotactic Body Proton Therapy for High-Risk, Medically Inoperable, Early-Stage Non-Small Cell Lung Cancer

PURPOSE

To report the feasibility of conducting a randomized study to compare the toxicity and efficacy of stereotactic body radiation therapy (SBRT) versus stereotactic body proton therapy (SBPT) for high-risk, medically inoperable, early-stage non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with medically inoperable NSCLC with high-risk features (centrally located or <5 cm T3 tumor or isolated lung parenchymal recurrences) were randomly assigned to SBRT or SBPT. Radiation dose was 50 Gy(relative biological effectiveness [RBE]) in 4 12.5-Gy(RBE) fractions prescribed to the planning target volume. Stereotactic body radiation therapy was given using 3-dimensional conformal radiation therapy or intensity modulated radiation therapy, and SBPT was given using passive scattering. Consistency in patient setup was ensured with on-board cone beam computed tomography for the SBRT group and with orthogonal X rays for the SBPT group.

RESULTS

The study closed early owing to poor accrual, largely because of insurance coverage and lack of volumetric imaging in the SBPT group. Ultimately, 21 patients were enrolled, and 19 patients who received 50 Gy in 4 fractions were included for analysis (9 SBRT, 10 SBPT). At a median follow-up time of 32 months, median overall survival time was 28 months in the SBRT group and not reached in the SBPT group. Three-year overall survival was 27.8% and 90%, 3-year local control was 87.5% (8 of 9) and 90.0% (9 of 10), and 3-year regional control was 47.6% (5 of 9) and 90% (9 of 10) in the SBRT and SBPT groups, respectively. One patient in the SBPT group developed grade 3 skin fibrosis. No patients experienced grade 4/5 toxicity.

CONCLUSION

Poor accrual, due to lack of volumetric imaging and insurance coverage for proton therapy, led to early closure of the trial and precluded accurate assessment of efficacy and toxicity. Comparable maturity of 2 radiation therapy modalities, particularly on-board imaging, and better insurance coverage for SBPT should be considered for future studies.

Stereotactic Body Radiotherapy for Early-Stage Non-Small-Cell Lung Cancer: American Society of Clinical Oncology Endorsement of the American Society for Radiation Oncology Evidence-Based Guideline

Purpose The American Society for Radiation Oncology (ASTRO) produced an evidence-based guideline on treatment with stereotactic body radiotherapy (SBRT) for patients with early-stage non-small-cell lung cancer. ASCO has a policy and set of procedures for endorsing and/or adapting clinical practice guidelines that have been developed by other professional organizations. Methods The ASTRO Evidence-Based Guideline for Stereotactic Body Radiotherapy for Early-Stage Non-Small-Cell Lung Cancer was reviewed for developmental rigor by methodologists. An ASCO Expert Panel updated the literature search and reviewed the guideline content and recommendations. Results The ASCO Expert Panel determined that the recommendations from the ASTRO guideline, published in 2017, are clear, thorough, and based on the most relevant scientific evidence. ASCO statements and minor modifications were added to enhance the applicability of the ASTRO guideline for the broader ASCO audience. Recommendations For standard operative risk patients with stage I NSCLC, SBRT is not recommended outside of a clinical trial. Lobectomy with systematic lymph node evaluation remains the recommended treatment, although a sublobar resection may be considered in select clinical scenarios. Recommendations are provided regarding the use of SBRT in high operative risk patients and for inoperative patients, including in challenging scenarios where tumors are: centrally located, > 5 cm in diameter, lacking tissue diagnosis, synchronous primary or multifocal, second primary after pneumonectomy, proximal to or involved with mediastinal structures, abutting the chest wall, or recurring after previous treatment. Qualifying statements are included to provide further guidance for implementation, and the importance of a discussion of treatment options among members of the multidisciplinary cancer care team is emphasized. Additional information is available at: www.asco.org/thoracic-cancer-guidelines and www.asco.org/guidelineswiki .

Progress in Radiotherapy for Regional and Oligometastatic Disease in 2017

This review highlights key publications and abstracts in the field of radiation oncology for lung cancer in 2017 and attempts to place these in the context of developments for the broader thoracic oncology community.

Combining radiation plus immunotherapy to improve systemic immune response

Over the past decade, the fields of oncology have made great strides in therapies. The development of new therapeutics and increased understanding of the role of the immune system in the development and treatment of cancer has led to increased collaboration between oncologic fields. Recent technologic advancements in radiation therapy (RT), including stereotactic beam radiation therapy (SBRT), have improved local control and offer an alternative to surgery for the control of oligometastatic disease. Immunotherapy has proven a promising therapeutic in the treatment of metastatic disease but treatment resistance remains a significant obstacle in the majority of patients. Together, radiation and immunotherapy offer potential to eliminate metastatic disease, reduce time to recurrence and improve overall survival. Major obstacles to these positive outcomes include high tumor burden, intratumoral heterogeneity, and the negative effects of tumor stroma, to name a few. Multimodality treatments are under heavy investigation. Promising data from clinical trials is emerging to highlight the value of RT in combination with immunotherapy. However, the mechanisms behind their synergistic effects remain to be fully elucidated. This review aims to highlight the existing literature and offers hypotheses to explain mechanisms behind the synergy of RT and immunotherapy.

Approaches to stereotactic body radiation therapy for large (≥5 centimeter) non-small cell lung cancer

Although larger (≥5 cm) node-negative non-small cell lung cancer (NSCLC) lesions are altogether uncommon, their incidence may increase following the implementation of lung cancer screening. A rigorous assessment of stereotactic body radiation therapy (SBRT) for these challenging cases is imperative not only owing to concerns of increased risks when delivering ablative doses to large volumes, but also due to lack of prospective data, as these patients were excluded from seminal phase II SBRT trials. In addition to appraising the available institutional or multi-institutional experiences, multiple strategies to reduce toxicities are discussed. These include exploration of several different dose/fractionation schemes and regimens, as well as specialized techniques for SBRT treatment planning and delivery. Because these lesions have a higher rate of occult lymphatic or distant spread, the role of systemic therapies (including chemotherapy and immunotherapy) are also discussed. Altogether, the publication of several key reports, entirely over the last few years, has created a more solid foundation with which to utilize evidence-based management for this unique patient population.

Radical Treatment of Stage II Non-small-cell Lung Cancer With Nonsurgical Approaches: A Multi-institution Report of Outcomes

INTRODUCTION

Standard management of stage II non-small-cell lung cancer (NSCLC) is surgery, often followed by adjuvant chemotherapy. However, some patients do not undergo surgery for various reasons. We examined outcomes in this defined patient group.

METHODS

We reviewed the records of patients with stage II NSCLC treated nonsurgically with curative intent from 2002 to 2012 across 3 academic cancer centers. Data collected included demographics, comorbidities, staging, treatments, and survival. The primary endpoint was overall survival (OS). We assessed factors associated with treatment choice and OS.

RESULTS

A total of 158 patients were included: the median age was 74 years (range, 50-91 years), 44% were female, and 68% had a performance status of 0 to 1. The stage II groupings of the patients were T2b-T3 N0 in 55% and N1 in 45%. The most common reasons for inoperability were inadequate pulmonary reserve (27%) and medical comorbidities (24%). All patients received radical radiotherapy (RT) (median, 60 Gy [range, 48-75 Gy]). Seventy-three percent received RT alone; 24% received concurrent and 3% sequential chemoradiotherapy (CRT). In multivariate analyses, CRT was less likely in older patients (≥ 70 years) (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.11-0.70; P = .006) and in patients with higher (> 5) Charlson comorbidity scores (OR, 0.34; 95% CI, 0.13-0.90; P = .03) or normal (< 10 × 10⁹/L) white blood cell counts (OR, 0.26; 95% CI, 0.09-0.73; P = .01). At the time of our analysis, 74% have died. The median OS was 22.9 months (range, 17.1-26.6 months). Patients who had undergone CRT had a significantly longer median OS than those receiving RT alone (39.1 vs. 20.5 months; P = .0019), confirmed in multivariate analysis (hazard ratio, 0.38; 95% CI, 0.21-0.69; P = .001).

CONCLUSION

Nonsurgical approaches to management of stage II NSCLC are varied. Treatment with CRT was associated with significantly longer survival compared with RT alone. A randomized trial may be warranted.