Optimal management of radiation pneumonitis: Findings of an international Delphi consensus study

PURPOSE

Radiation pneumonitis (RP) is a dose-limiting toxicity for patients undergoing radiotherapy (RT) for lung cancer, however, the optimal practice for diagnosis, management, and follow-up for RP remains unclear. We thus sought to establish expert consensus recommendations through a Delphi Consensus study.

METHODS

In Round 1, open questions were distributed to 31 expert clinicians treating thoracic malignancies. In Round 2, participants rated agreement/disagreement with statements derived from Round 1 answers using a 5-point Likert scale. Consensus was defined as ≥ 75 % agreement. Statements that did not achieve consensus were modified and re-tested in Round 3.

RESULTS

Response rate was 74 % in Round 1 (n = 23/31; 17 oncologists, 6 pulmonologists); 82 % in Round 2 (n = 19/23; 15 oncologists, 4 pulmonologists); and 100 % in Round 3 (n = 19/19). Thirty-nine of 65 Round 2 statements achieved consensus; a further 10 of 26 statements achieved consensus in Round 3. In Round 2, there was agreement that risk stratification/mitigation includes patient factors; optimal treatment planning; the basis for diagnosis of RP; and that oncologists and pulmonologists should be involved in treatment. For uncomplicated radiation pneumonitis, an equivalent to 60 mg oral prednisone per day, with consideration of gastroprotection, is a typical initial regimen. However, in this study, no consensus was achieved for dosing recommendation. Initial steroid dose should be administered for a duration of 2 weeks, followed by a gradual, weekly taper (equivalent to 10 mg prednisone decrease per week). For severe pneumonitis, IV methylprednisolone is recommended for 3 days prior to initiating oral corticosteroids. Final consensus statements included that the treatment of RP should be multidisciplinary, the uncertainty of whether pneumonitis is drug versus radiation-induced, and the importance risk stratification, especially in the scenario of interstitial lung disease.

CONCLUSIONS

This Delphi study achieved consensus recommendations and provides practical guidance on diagnosis and management of RP.

A population-based analysis of the management of symptoms of depression among patients with stage IV non-small cell lung cancer (NSCLC) in Ontario, Canada

PURPOSE

Patients with lung cancer can experience significant psychological morbidities including depression. We characterize patterns and factors associated with interventions for symptoms of depression in stage IV non-small cell lung cancer (NSCLC).

METHODS

We conducted a population-based cohort study using health services administrative data in Ontario, Canada of stage IV NSCLC diagnosed from January 2007 to September 2018. A positive symptom of depression score was defined by reporting at least one ESAS (Edmonton Symptom Assessment System) depression score ≥ 2 following diagnosis until the end of follow-up (September 2019). Patient factors included age, sex, comorbidity burden, rurality of residence, and neighbourhood income quintile. Interventions included psychiatry assessment, psychology referral, social work referral and anti-depressant medical therapy (for patients ≥ 65 years with universal drug coverage). Multivariable modified Poisson regression models were used to examine the association between patient factors and intervention use for patients who reported symptoms of depression.

RESULTS

In the cohort of 13,159 patients with stage IV NSCLC lung cancer, symptoms of depression were prevalent (71.4%, n = 9,397). Patients who reported symptoms of depression were more likely to receive psychiatry assessment/psychology referral (7.8% vs 3.5%; SD [standardized difference] 0.19), social work referral (17.4% vs 11.9%; SD 0.16) and anti-depressant prescriptions (23.8% vs 13.8%; SD 0.26) when compared to patients who did not report symptoms of depression respectively. In multivariable analyses, older patients were less likely to receive any intervention. Females were more likely to obtain a psychiatry assessment/psychology referral or social work referral. In addition, patients from non-major urban or rural residences were less likely to receive psychiatry assessment/psychology referral or social work referral, however patients from rural residences were more likely to be prescribed anti-depressants.

CONCLUSIONS

There is high prevalence of symptoms of depression in stage IV NSCLC. We identify patient populations, including older patients and rural patients, who are less likely to receive interventions that will help identifying and screening for symptoms of depression.

Delphi consensus on stereotactic ablative radiotherapy for oligometastatic and oligoprogressive renal cell carcinoma-a European Society for Radiotherapy and Oncology study endorsed by the European Association of Urology

The purpose of this European Society for Radiotherapy and Oncology (ESTRO) project, endorsed by the European Association of Urology, is to explore expert opinion on the management of patients with oligometastatic and oligoprogressive renal cell carcinoma by means of stereotactic ablative radiotherapy (SABR) on extracranial metastases, with the aim of developing consensus recommendations for patient selection, treatment doses, and concurrent systemic therapy. A questionnaire on SABR in oligometastatic renal cell carcinoma was prepared by a core group and reviewed by a panel of ten prominent experts in the field. The Delphi consensus methodology was applied, sending three rounds of questionnaires to clinicians identified as key opinion leaders in the field. At the end of the third round, participants were able to find consensus on eight of the 37 questions. Specifically, panellists agreed to apply no restrictions regarding age (25 [100%) of 25) and primary renal cell carcinoma histology (23 [92%] of 25) for SABR candidates, on the upper threshold of three lesions to offer ablative treatment in patients with oligoprogression, and on the concomitant administration of immune checkpoint inhibitor. SABR was indicated as the treatment modality of choice for renal cell carcinoma bone oligometatasis (20 [80%] of 25) and for adrenal oligometastases 22 (88%). No consensus or major agreement was reached regarding the appropriate schedule, but the majority of the poll (54%-58%) retained the every-other-day schedule as the optimal choice for all the investigated sites. The current ESTRO Delphi consensus might provide useful direction for the application of SABR in oligometastatic renal cell carcinoma and highlight the key areas of ongoing debate, perhaps directing future research efforts to close knowledge gaps.

Safety and Efficacy of Stereotactic Body Radiation Therapy for Ultra-central Thoracic Tumors: A Single Center Retrospective Review

PURPOSE

We sought to evaluate the toxicity and efficacy of stereotactic body radiation therapy (SBRT) for ultracentral thoracic tumors at our institution.

METHODS AND MATERIALS

Patients with ultracentral lung tumors or nodes, defined as having the planning target volume (PTV) overlapping or abutting the central bronchial tree and/or esophagus, treated at our institution with SBRT between 2009 and 2019 were retrospectively reviewed. All SBRT plans were generated with the goal of creating homogenous dose distributions. The primary endpoint was incidence of SBRT-related grade ≥3 toxicity, defined using the Common Terminology Criteria for Adverse Events (V5.0). Secondary endpoints included local failure (LF), progression-free survival (PFS), and overall survival. Competing risk analysis was used to estimate incidence and identify predictors of severe toxicity and LF, while the Kaplan-Meier method was used to estimate PFS and OS.

RESULTS

A total of 154 patients receiving 162 ultracentral courses of SBRT were included. The most common prescription was 50 Gy in 5 fractions (42%), with doses ranging from 30 to 55 Gy in 5 fractions (BED10 range, 48-115 Gy). The incidence of severe toxicity was 9.4% at 3 years. The most common severe toxicity was pneumonitis (n = 4). There was 1 possible treatment-related death from pneumonitis/pneumonia. Predictors of severe toxicity included increased PTV size, decreased PTV V95%, lung V5 Gy, and lung V20 Gy. The incidence of LF was 14% at 3 years. Predictors of LF included younger age and greater volume of overlap between the PTV and esophagus. The median PFS was 8.8 months, while the median overall survival was 44.0 months.

CONCLUSIONS

In the largest case series of ultracentral thoracic SBRT to date, homogenously prescribed SBRT was associated with relatively low rates of severe toxicity and LF. Predictors of toxicity should be interpreted in the context of the heterogeneity in toxicities observed.

Stereotactic Radiation for Ultra-Central Non-Small Cell Lung Cancer: A Safety and Efficacy Trial (SUNSET)

PURPOSE

The use of stereotactic body radiation therapy for tumors in close proximity to the central mediastinal structures has been associated with a high risk of toxicity. This study (NCT03306680) aimed to determine the maximally tolerated dose of stereotactic body radiation therapy for ultracentral non-small cell lung carcinoma, using a time-to-event continual reassessment methodology.

METHODS AND MATERIALS

Patients with T1-3N0M0 (≤6 cm) non-small cell lung carcinoma were eligible. The maximally tolerated dose was defined as the dose of radiation therapy associated with a ≤30% rate of grade (G) 3 to 5 prespecified treatment-related toxicity occurring within 2 years of treatment. The starting dose level was 60 Gy in 8 daily fractions. The dose-maximum hotspot was limited to 120% and within the planning tumor volume; tumors with endobronchial invasion were excluded. This primary analysis occurred 2 years after completion of accrual.

RESULTS

Between March 2018 and April 2021, 30 patients were enrolled at 5 institutions. The median age was 73 years (range, 65-87) and 17 (57%) were female. Planning tumor volume was abutting proximal bronchial tree in 19 (63%), esophagus 5 (17%), pulmonary vein 1 (3.3%), and pulmonary artery 14 (47%). All patients received 60 Gy in 8 fractions. The median follow-up was 37 months (range, 8.9-51). Two patients (6.7%) experienced G3-5 adverse events related to treatment: 1 patient with G3 dyspnea and 1 G5 pneumonia. The latter had computed tomography findings consistent with a background of interstitial lung disease. Three-year overall survival was 72.5% (95% CI, 52.3%-85.3%), progression-free survival 66.1% (95% CI, 46.1%-80.2%), local control 89.6% (95% CI, 71.2%-96.5%), regional control 96.4% (95% CI, 77.2%-99.5%), and distant control 85.9% (95% CI, 66.7%-94.5%). Quality-of-life scores declined numerically over time, but the decreases were not clinically or statistically significant.

CONCLUSIONS

Sixty Gy in 8 fractions, planned and delivered with only a moderate hotspot, has a favorable adverse event rate within the prespecified acceptability criteria and results in excellent control for ultracentral tumors.

Utility of molecular markers in predicting local control specific to lung cancer spine metastases treated with stereotactic body radiotherapy

BACKGROUND AND PURPOSE

We report outcomes following spine stereotactic body radiotherapy (SBRT) in metastatic non-small cell lung cancer (NSCLC) and the significance of programmed death-ligand 1 (PD-L1) status, epidermal growth factor receptor (EGFR) mutation and timing of immune check point inhibitors (ICI) on local failure (LF).

MATERIALS AND METHODS

165 patients and 389 spinal segments were retrospectively reviewed from 2009 to 2021. Baseline patient characteristics, treatment and outcomes were abstracted. Primary endpoint was LF and secondary, overall survival (OS) and vertebral compression fracture (VCF). Multivariable analysis (MVA) evaluated factors predictive of LF and VCF.

RESULTS

The median follow-up and OS were: 13.0 months (range, 0.5-95.3 months) and 18.4 months (95% CI 11.4-24.6). 52.1% were male and 76.4% had adenocarcinoma. Of the 389 segments, 30.3% harboured an EGFR mutation and 17.0% were PD-L1 ≥ 50%. The 24 months LF rate in PD-L1 ≥ 50% vs PD-L1 < 50% was 10.7% vs. 38.0%, and in EGFR-positive vs. negative was 18.1% vs. 30.0%. On MVA, PD-L1 status of ≥ 50% (HR 0.32, 95% CI 0.15-0.69, p = 0.004) significantly predicted for lower LF compared to PD-L1 < 50%. Lower LF trend was seen with ICI administration peri and post SBRT (HR 0.41, 95% CI 0.16-1.05, p = 0.062). On MVA, polymetastatic disease (HR 3.28, 95% CI 1.84-5.85, p < 0.0001) and ECOG ≥ 2 (HR 1.87, 95% CI 1.16-3.02, p = 0.011) significantly predicted for worse OS and absence of baseline VCF predicted for lower VCF rate (HR 0.20, 95% CI 0.10-0.39, p < 0.0001).

CONCLUSION

We report a significant association of PD-L1 ≥ 50% status on improved LC rates from spine SBRT in NSCLC patients.

Stereotactic Radiation Therapy in Early Non-Small Cell Lung Cancer and Interstitial Lung Disease: A Nonrandomized Clinical Trial

Importance

Patients with interstitial lung disease (ILD) and early-stage non-small cell lung cancer (NSCLC) have been reported to be at high risk of toxic effects after stereotactic ablative radiotherapy (SABR), but for many patients, there are limited alternative treatment options.

Objective

To prospectively assess the benefits and toxic effects of SABR in this patient population.

Design, Setting, and Participants

This prospective cohort study was conducted at 6 academic radiation oncology institutions, 5 in Canada and 1 in Scotland, with accrual between March 7, 2019, and January 12, 2022. Patients aged 18 years or older with fibrotic ILD and a diagnosis of T1-2N0 NSCLC who were not candidates for surgical resection were enrolled.

Intervention

Patients were treated with SABR to a dose of 50 Gy in 5 fractions every other day.

Main Outcomes and Measures

The study prespecified that SABR would be considered worthwhile if median overall survival-the primary end point-was longer than 1 year, with a grade 3 to 4 risk of toxic effects less than 35% and a grade 5 risk of toxic effects less than 15%. Secondary end points included toxic effects, progression-free survival (PFS), local control (LC), quality-of-life outcomes, and changes in pulmonary function. Intention-to-treat analysis was conducted.

Results

Thirty-nine patients enrolled and received SABR. Median age was 78 (IQR, 67-83) years and 59% (n = 23) were male. At baseline, 70% (26 of 37) of patients reported dyspnea, median forced expiratory volume in first second of expiration was 80% (IQR, 66%-90%) predicted, median forced vital capacity was 84% (IQR, 69%-94%) predicted, and median diffusion capacity of the lung for carbon monoxide was 49% (IQR, 38%-61%) predicted. Median follow-up was 19 (IQR, 14-25) months. Overall survival at 1 year was 79% (95%, CI 62%-89%; P < .001 vs the unacceptable rate), and median overall survival was 25 months (95% CI, 14 months to not reached). Median PFS was 19 months (95% CI, 13-28 months), and 2-year LC was 92% (95% CI, 69%-98%). Adverse event rates (highest grade per patient) were grade 1 to 2: n = 12 (31%), grade 3: n = 4 (10%), grade 4: n = 0, and grade 5: n = 3 (7.7%, all due to respiratory deterioration).

Conclusions and Relevance

In this trial, use of SABR in patients with fibrotic ILD met the prespecified acceptability thresholds for both toxicity and efficacy, supporting the use of SABR for curative-intent treatment after a careful discussion of risks and benefits.

Trial Registration

ClinicalTrials.gov Identifier: NCT03485378.

Detection of Circulating Tumor DNA After Stereotactic Ablative Radiotherapy in Patients With Unbiopsied Lung Tumors (SABR-DETECT)

For patients with stage I/IIA non-small-cell lung cancer (NSCLC), surgical resection is the standard treatment. However, some of these patients are not candidates for surgery or refuse a surgical option. Definitive stereotactic ablative radiotherapy (SABR) is a standard approach in these patients. Approximately 15% of patients undergoing SABR for localized NSCLC will experience a recurrence within 2 years. Furthermore, many of these patients are deemed appropriate for SABR without a tissue diagnosis, based on the likelihood of malignancy which can be calculated by validated models. A liquid biopsy, detecting ctDNA, would be useful in early detection of recurrences, and documenting a cancer diagnosis in patients without a biopsy. This is a multi-institutional study enrolling patients with suspected stage I/IIA NSCLC and a pretreatment likelihood of malignancy of ≥60% using the validated models for patients without a tissue diagnosis, in cohort 1 (n = 45). The second cohort will consist of biopsied patients (n = 30-60). SABR will be delivered as per risk-adapted protocol. Plasma will be collected for ctDNA analysis prior to the first fraction of SABR, 24 to 72 hours after first fraction, and at 3, 6, 9, 12, 18, and 24-months. The patients will be followed up with imaging at 3, 6, 9, 12, 18, and 24-months. The primary objective is to assess whether a cancer detection liquid biopsy platform can predict recurrence of NSCLC. The secondary objectives are to assess the impact of SABR on detection rates of ctDNA in patients undergoing SABR and to correlate ctDNA positivity and pretreatment probability of malignancy (NCT05921474).

Stereotactic Body Radiotherapy for Extracranial Oligometastatic Disease from Head and Neck Primary Cancers: A Systematic Review and Meta-Analysis

INTRODUCTION

Stereotactic body radiotherapy (SBRT) is increasingly used to treat disease in the oligometastatic (OM) setting due to mounting evidence demonstrating its efficacy and safety. Given the low population representation in prospective studies, we performed a systematic review and meta-analysis of outcomes of HNC patients with extracranial OM disease treated with SBRT.

METHODS

A systematic review was conducted with Cochrane, Medline, and Embase databases queried from inception to August 2022 for studies with extracranial OM HNC treated with stereotactic radiotherapy. Polymetastatic patients (>five lesions), mixed-primary cohorts failing to report HNC separately, lack of treatment to all lesions, nonquantitative endpoints, and other definitive treatments (surgery, conventional radiotherapy, and radioablation) were excluded. The meta-analysis examined the pooled effects of 12- and 24-month local control (LC) per lesion, progression-free survival (PFS), and overall survival (OS). Weighted random-effects were assessed using the DerSimonian and Laird method, with heterogeneity evaluated using the I2 statistic and Cochran Qtest. Forest plots were generated for each endpoint.

RESULTS

Fifteen studies met the inclusion criteria (639 patients, 831 lesions), with twelve eligible for quantitative synthesis with common endpoints and sufficient reporting. Fourteen studies were retrospective, with a single prospective trial. Studies were small, with a median of 32 patients (range: 6-81) and 63 lesions (range: 6-126). The OM definition varied, with a maximum of two to five metastases, mixed synchronous and metachronous lesions, and a few studies including oligoprogressive lesions. The most common site of metastasis was the lung. Radiation was delivered in 1-10 fractions (20-70 Gy). The one-year LC (LC1), reported in 12 studies, was 86.9% (95% confidence interval [CI]: 79.3-91.9%). LC2 was 77.9% (95% CI: 66.4-86.3%), with heterogeneity across studies. PFS was reported in five studies, with a PFS1 of 43.0% (95% CI: 35.0-51.4%) and PFS2 of 23.9% (95% CI: 17.8-31.2%), with homogeneity across studies. OS was analyzed in nine studies, demonstrating an OS1 of 80.1% (95% CI: 74.2-85.0%) and OS2 of 60.7% (95% CI: 51.3-69.4%). Treatment was well tolerated with no reported grade 4 or 5 toxicities. Grade 3 toxicity rates were uniformly below 5% when reported.

CONCLUSIONS

SBRT offers excellent LC and promising OS, with acceptable toxicities in OM HNC. Durable PFS remains rare, highlighting the need for effective local or systemic therapies in this population. Further investigations on concurrent and adjuvant therapies are warranted.

Single vs. multiple fraction non-inferiority trial of stereotactic ablative radiotherapy for the comprehensive treatment of oligo-metastases/progression: SIMPLIFY-SABR-COMET

BACKGROUND

Radiotherapy delivery regimens can vary between a single fraction (SF) and multiple fractions (MF) given daily for up to several weeks depending on the location of the cancer or metastases. With limited evidence comparing fractionation regimens for oligometastases, there is support to explore toxicity levels to nearby organs at risk as a primary outcome while using SF and MF stereotactic ablative radiotherapy (SABR) as well as explore differences in patient-reported quality of life and experience.

METHODS

This study will randomize 598 patients in a 1:1 ratio between the standard arm (MF SABR) and the experimental arm (SF SABR). This trial is designed as two randomized controlled trials within one patient population for resource efficiency. The primary objective of the first randomization is to determine if SF SABR is non-inferior to MF SABR, with respect to healthcare provider (HCP)-reported grade 3-5 adverse events (AEs) that are related to SABR. Primary endpoint is toxicity while secondary endpoints include lesional control rate (LCR), and progression-free survival (PFS). The second randomization (BC Cancer sites only) will allocate participants to either complete quality of life (QoL) questionnaires only; or QoL questionnaires and a symptom-specific survey with symptom-guided HCP intervention. The primary objective of the second randomization is to determine if radiation-related symptom questionnaire-guided HCP intervention results in improved reported QoL as measured by the EuroQoL-5-dimensions-5levels (EQ-5D-5L) instrument. The primary endpoint is patient-reported QoL and secondary endpoints include: persistence/resolution of symptom reporting, QoL, intervention cost effectiveness, resource utilization, and overall survival.

DISCUSSION

This study will compare SF and MF SABR in the treatment of oligometastases and oligoprogression to determine if there is non-inferior toxicity for SF SABR in selected participants with 1-5 oligometastatic lesions. This study will also compare patient-reported QoL between participants who receive radiation-related symptom-guided HCP intervention and those who complete questionnaires alone.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT05784428. Date of Registration: 23 March 2023.

Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma: Meta-Analysis and International Stereotactic Radiosurgery Society Practice Guidelines

This systematic review and meta-analysis reports on outcomes and hepatic toxicity rates after stereotactic body radiation therapy (SBRT) for liver-confined hepatocellular carcinoma (HCC) and presents consensus guidelines regarding appropriate patient management. Using the Preferred Reporting Items for Systemic Review and Meta-Analyses guidelines, a systematic review was performed from articles reporting outcomes at ≥5 years published before October 2022 from the Embase, MEDLINE, Cochrane, and Scopus databases with the following search terms: ("stereotactic body radiotherapy" OR "SBRT" OR "SABR" OR "stereotactic ablative radiotherapy") AND ("hepatocellular carcinoma" OR "HCC"). An aggregated data meta-analysis was conducted to assess overall survival (OS) and local control (LC) using weighted random effects models. In addition, individual patient data analyses incorporating data from 6 institutions were conducted as their own subgroup analyses. Seventeen observational studies, comprising 1889 patients with HCC treated with ≤9 SBRT fractions, between 2003 and 2019, were included in the aggregated data meta-analysis. The 3- and 5-year OS rates after SBRT were 57% (95% confidence interval [CI], 47%-66%) and 40% (95% CI, 29%-51%), respectively. The 3- and 5-year LC rates after SBRT were 84% (95% CI, 77%-90%) and 82% (95% CI, 74%-88%), respectively. Tumor size was the only prognostic factor for LC. Tumor size and region were significantly associated with OS. Five-year LC and OS rates of 79% (95% CI, 0.74-0.84) and 25% (95% CI, 0.20-0.30), respectively, were observed in the individual patient data analyses. Factors prognostic for improved OS were tumor size <3 cm, Eastern region, Child-Pugh score ≤B7, and the Barcelona Clinic Liver Cancer stage of 0 and A. The incidence of severe hepatic toxicity varied according to the criteria applied. SBRT is an effective treatment modality for patients with HCC with mature follow-up. Clinical practice guidelines were developed on behalf of the International Stereotactic Radiosurgery Society (ISRS).

Referred molecular testing as a barrier to optimal treatment decision making in metastatic non-small cell lung cancer: Experience at a tertiary academic institution in Canada

BACKGROUND

Molecular testing is critical to guiding treatment approaches in patients with metastatic non-small cell lung cancer (mNSCLC), with testing delays adversely impacting the timeliness of treatment decisions. Here, we aimed to evaluate the time from initial mNSCLC diagnosis to treatment decision (TTD) following implementation of in-house EGFR, ALK, and PD-L1 testing at our institution.

METHODS

We conducted a retrospective chart review of 165 patients (send-out testing, n = 92; in-house testing, n = 73) with newly diagnosed mNSCLC treated at our institution. Data were compared during the send-out (March 2017-May 2019) and in-house (July 2019-March 2021) testing periods. We performed a detailed workflow analysis to provide insight on the pre-analytic, analytic, and post-analytic intervals that constituted the total TTD.

RESULTS

TTD was significantly shorter with in-house testing (10 days vs. 18 days, p < 0.0001), driven largely by decreased internal handling and specimen transit times (2 days vs. 3 days, p < 0.0001) and laboratory turnaround times (TAT, 3 days vs. 8 days, p < 0.0001), with 96% of in-house cases meeting the international guideline of a ≤ 10-day intra-laboratory TAT (vs. 74% send-out, p < 0.001). Eighty-eight percent of patients with in-house testing had results available at their first oncology consultation (vs. 52% send-out, p < 0.0001), and all patients with in-house testing had results available at the time of treatment decision (vs. 86% send-out, p = 0.57).

CONCLUSION

Our results demonstrate the advantages of in-house biomarker testing for mNSCLC at a tertiary oncology center. Incorporation of in-house testing may reduce barriers to offering personalized medicine by improving the time to optimal systemic therapy decision.

Enhancing Symptom Screening and Patient Education Among Patients with Metastatic Lung Cancer: a Qualitative Analysis

We explored perspectives of patients with metastatic non-small cell lung cancer (mNSCLC) on symptom screening and population-level patient-reported outcome (PRO) data regarding common symptom trajectories in the year after diagnosis. A qualitative study of patients with mNSCLC was conducted at a Canadian tertiary cancer centre. English-speaking patients diagnosed ≥ 6 months prior to study invitation were recruited, and semi-structured one-on-one interviews were conducted. Patient and treatment characteristics were obtained via chart review. Anonymized interview transcripts underwent deductive-inductive coding and thematic content analysis. Among ten participants (5 (50%) females; median (range) age, 68 (56-77) years; median (range) time since diagnosis, 28.5 (6-72) months; 6 (60%) with smoking histories), six themes were identified in total. Two themes were identified regarding symptom screening: (1) screening is useful for symptom self-monitoring and disclosure to the healthcare team, (2) screening of additional quality-of-life (QOL) domains (smoking-related stigma, sexual dysfunction, and financial toxicity) is desired. Four themes were identified regarding population-level symptom trajectory PRO data: (1) data provide reassurance and motivation to engage in symptom self-management, (2) data should be disclosed after an oncologic treatment plan is developed, (3) data should be communicated via in-person discussion with accompanying patient-education resources, and (4) communication of data should include reassurance about symptom stabilization, acknowledgement of variability in patient experience, and strategies for symptom self-management. The themes and recommendations derived from the patient experience with mNSCLC provide guidance for enhanced symptom screening and utilization of population-level symptom trajectory data for patient education.

Stereotactic body radiotherapy for primary renal cell carcinoma: a systematic review and practice guideline from the International Society of Stereotactic Radiosurgery (ISRS)

Surgery is the standard of care for patients with primary renal cell carcinoma. Stereotactic body radiotherapy (SBRT) is a novel alternative for patients who are medically inoperable, technically high risk, or who decline surgery. Evidence for using SBRT in the primary renal cell carcinoma setting is growing, including several rigorously conducted prospective clinical trials. This systematic review was performed to assess the safety and efficacy of SBRT for primary renal cell carcinoma. Review results then formed the basis for the practice guidelines described, on behalf of the International Stereotactic Radiosurgery Society. 3972 publications were screened and 36 studies (822 patients) were included in the analysis. Median local control rate was 94·1% (range 70·0-100), 5-year progression-free survival was 80·5% (95% CI 72-92), and 5-year overall survival was 77·2% (95% CI 65-89). These practice guidelines addressed four key clinical questions. First, the optimal dose fractionation was 25-26 Gy in one fraction, or 42-48 Gy in three fractions for larger tumours. Second, routine post-treatment biopsy is not recommended as it is not predictive of patient outcome. Third, SBRT for primary renal cell carcinoma in a solitary kidney is safe and effective. Finally, guidelines for post-treatment follow-up are described, which include cross-axial imaging of the abdomen including both kidneys, adrenals, and surveillance of the chest initially every 6 months. This systematic review and practice guideline support the practice of SBRT for primary renal cell carcinoma as a safe and effective standard treatment option. Randomised trials with surgery and invasive ablative therapies are needed to further define best practice.

Radiation therapy options in kidney cancer

PURPOSE OF REVIEW

In this review, the authors discuss the use of stereotactic body radiation therapy (SBRT) for the treatment of primary and metastatic renal cell carcinoma (RCC).

RECENT FINDINGS

For primary RCC treated with SBRT, local control is estimated at >95%, and grade 3-4 toxicity is limited at ≤5%. The difference in glomerular filtration rate pretreatment versus posttreatment was about 7.7 ml/min. For metastatic RCC treated with SBRT, the 1-year local control is ~90%. The incidence of any grade 3-4 toxicity is ~1%. Several ongoing trials are evaluating SBRT in combination or in lieu of systemic therapy. There are many unknowns remaining in the treatment of RCC, including tumor prognostication, treatment selection, and treatment delivery.

SUMMARY

Stereotactic body radiation therapy is a safe and effective treatment option for patients with primary and metastatic RCC.

Palliative Care Among Lung Cancer Patients With and Without COPD: A Population-Based Cohort Study

CONTEXT

Lung cancer patients with chronic obstructive pulmonary disease (COPD) may have greater palliative care needs due to poor prognosis and symptom burden.

OBJECTIVES

We sought to compare the provision of timely palliative care and symptom burden by COPD status.

METHODS

We performed a retrospective, population-based cohort study of individuals diagnosed with lung cancer in Ontario, Canada (2009-2019) using health administrative databases and cancer registries. The impact of COPD on the probability of receiving palliative care was determined accounting for dying as a competing event, overall and stratified by stage. The provision of palliative care for patients with severe symptoms (Edmonton Symptom Assessment Scale score ≥ 7), location of the first palliative care visit and symptom severity were compared by COPD status.

RESULTS

A total of 74,993 patients were included in the study (48% of patients had available symptom data). At the time of lung cancer diagnosis, 50% of patients had COPD. Stage I-III patients with COPD were more likely to receive palliative care (adjusted Hazard Ratio (HR)s: 1.05-1.31) with no difference for stage IV (1.02, 95% CI: 1.00-1.04). Despite having severe symptoms, very few patients with early-stage disease received palliative care (Stage I: COPD-23% vs. no COPD-18%, SMD = 0.12). Most patients (84%) reported severe symptoms and COPD worsened symptom burden, especially among early-stage patients.

CONCLUSION

COPD impacts the receipt of palliative care and symptom burden for patients with early-stage lung cancer. Many patients with severe symptoms did not receive palliative care, suggesting unmet needs among this vulnerable population.

Unanticipated Radiation Replanning for Stage III Non-small Cell Lung Cancer

Purpose

The purpose of this study was to identify factors associated with unanticipated radiation therapy (RT) replanning in stage III non-small cell lung cancer (NSCLC).

Methods and Materials

Patients from a single institution with newly diagnosed stage III NSCLC treated with radical RT from January 1, 2016, to December 31, 2019, were retrospectively analyzed. The frequency and reasons for replanning were determined. Logistic regression analysis was used to identify factors associated with replanning.

Results

Of 144 patients included in this study, 11% (n = 16) required replanning after the start of RT. The reason for replanning in these 16 patients was changes in the target detected by cone beam computed tomography (shift in 10 patients, shrinkage in 5 patients, and growth in 1 patient). Larger planning target volume (primary and nodal) was statistically predictive of replanning (odds ratio, 2.5; 95% CI, 1.2-5.4; P = .02). The actuarial median overall survival was 33.3 months (95% CI, 10.3-43.9) for the 16 patients who were replanned and 36.3 months (95% CI, 27.4-66.5) for the remaining 128 patients (P = .96). The median time to local recurrence was 25.0 months (95% CI, 10.3-41.3) for those patients who underwent replanning, which was similar to those patients who did not undergo replanning (19.5 months; 95% CI, 11.8-23.2; P = .28).

Conclusions

In this study, 11% of patients treated with radical RT for NSCLC required replanning due to changes in the target detected by cone beam computed tomography. A larger planning target volume predicts a higher likelihood of requiring adaptive RT. Overall survival and local control were similar between patients who were replanned compared with those who were not replanned.

Uncovering the Armpit of Axillary SBRT

PURPOSE/OBJECTIVE(S)

The growing use of stereotactic body radiotherapy (SBRT) in metastatic cancer has led to applications in new and unique anatomic locations, highlighting the importance of effective, safe, reproducible treatment delivery. The objective of this study was to review our institutional SBRT experience for axillary metastases (AM), focusing on outcomes, safety and process.

MATERIALS/METHODS

In this ethics approved single-institution retrospective review, patients treated with SBRT to AM from 2014-2022 had tumor, treatment planning, and dosimetric variables abstracted. Toxicity was assessed per Common Terminology for Adverse Events V5.0. Cumulative incidence functions were used to estimate the incidence of local failure (LF), with death as competing risk. Kaplan-Meier method was used to estimate progression-free (PFS) and overall survival (OS).

RESULTS

We analyzed 37 patients with 39 AM who received SBRT. Patients were predominantly female (60%), Eastern Cooperative Oncology Group performance status 0-1 (62%), and elderly (median age: 72), with a median follow-up of 14.6 months. Common primary sites included breast (n = 16, 43%), skin (n = 7, 19%), and lung (n = 5, 14%). Treatment indication included oligoprogression (n = 18, 46%), oligometastases (n = 14, 36%) and symptomatic progression (n = 7, 18%). A minority had prior overlapping radiation (n = 7, 18%) or regional surgery (n = 4, 11%), while most had prior systemic therapy (n = 26, 70%). Significant heterogeneity in simulation, planning and treatment was identified. Immobilization included 5-point thermoplastic mask (n = 12, 32%), Vacloc (n = 12, 32%) arms-up thorax bag (n = 11, 30%). 4-D CT scans were obtained in 46%, MR simulation in 21%, and intravenous contrast in 10%. Median dose was 40 Gy (interquartile range (IQR): 35-40) in 5 fractions, (BED10 = 72 Gy), over a median of 12 days (IQR: 9-14). Seventeen cases (44%) utilized a low-dose elective volume to cover remaining axilla; 14% used a high dose clinical target volume. Median planning target volume margin was 5mm (range: 3-10mm), and plans were generated with 5 different dose constraint protocols. At first radiographic assessment, 87% had partial or complete response, with a single progression. Of symptomatic patients (n = 14), 57% had complete symptom resolution and 21% had improvement. One and 2-year LF rate were 19% and 31%, respectively. Median OS was 21.0 months (95% [Confidence Interval (CI)] 17.3-not reached) and median PFS was 7.0 months (95% [CI] 4.3-11.3). Acute and late toxicities were uncommon, with two grade 3 events (1 plexopathy in a case with tumor involving brachial plexus, 1 skin ulceration) identified, and no grade 4/5.

CONCLUSION

In this series of AM SBRT, low rates of toxicity, and good rates of LF and symptom improvement were observed. As treatment was delivered with a variety of individual treatment differences, an institutional protocol is under development to standardize technique, optimize efficiency and improve evaluability.

All that Glitters is Not Gold: Examining Cost Effectiveness Analyses in Radiation Oncology

PURPOSE/OBJECTIVE(S)

Cost effectiveness analyses (CEA) provide data for health policy decisions in resource constrained environments. These are important in Radiation Oncology as infrastructure and delivery costs increase and indications expand. The purpose of this study was to systematically review methodologic quality and trends in CEAs involving radiotherapy (RT).

MATERIALS/METHODS

A systematic review was performed on cost effectiveness/utility studies involving RT, querying PubMed and Embase from inception to September 2020. Non-English, reviews, abstracts and cost-only studies were excluded. Independent reviewers screened and abstracted study demographics, economic parameters and methodological details.

RESULTS

After screening 1652 abstracts, 214 met criteria. The first publication was in 1995, and more than half (n = 113, 53%) were published after 2014. Author institutions were from North America (n = 128, 60%), Europe (n = 49, 23%) and Asia (n = 30, 14%) with most reporting in US$ (n = 143, 67%). A majority utilized a decision model (n = 164, 77%), healthcare payer perspective (n = 171, 80%) and a finite time horizon (n = 108, 50%). Publications spanned 96 unique journals, most commonly International Journal of Radiation and Oncological Biology and Physics (n = 35, 16%). Treatment intent was curative in 171 studies. Disease sites included breast (n = 34, 16%), genitourinary (n = 31, 14%), and gastrointestinal (n = 31, 14%). RT was mostly used as primary treatment (n = 144, 67%), followed by adjuvant (n = 70, 33%) and neoadjuvant (n = 10, 5%). Emerging topics included stereotactic RT (n = 45, 21%), immunotherapy (n = 6, 3%), oligometastasis (n = 4, 2%), and heavy particles (n = 23, 11%). RT was compared to other RT (n = 136, 64%), surgery (n = 43, 20%), drugs (n = 14, 7%) and observation (n = 31, 17%). Incomplete reporting was common. Missing elements included analysis perspective (n = 13, 6%), time horizon (n = 38, 18%), discounting of utilities (n = 71, 33%) or costs (n = 54, 25%), and willingness-to-pay threshold (n = 59, 28%). Furthermore, 27 studies did not perform sensitivity analyses, 36 did not evaluate incremental cost-effectiveness ratio and only 60 explicitly utilized recognized reporting guidelines. Conflict of interest statements were found in 63%, with sponsor statements in 59%; 25% were industry sponsors. Outcome parameters were obtained from primary (author institution/trial data) sources in 33%, including randomized trials (RCTs) (n = 20, 9%), retrospective data (n = 20, 9%) and population data (n = 9, 4%). The remainder utilized secondary sources including RCTs (n = 71, 33%), retrospective data (n = 35, 16%) or meta-analyses (n = 11, 5%). Outcomes included quality adjusted life years (n = 158, 74%), life-years (n = 30, 14%) or toxicity (n = 26,12%). 31% utilized author generated utilities; of literature derived only 49% were matched to disease and clinical context.

CONCLUSION

While CEAs are increasingly common in RT, reporting and methodologic rigor must improve. Greater use of published guidelines will improve data quality for decision makers.

Long-Term Toxicity in Patients Receiving Radiotherapy for Ultracentral Stage I Non-Small Cell Lung Cancer - A Secondary Analysis of the LUSTRE Randomized Trial

PURPOSE/OBJECTIVE(S)

Hypofractionated and stereotactic body radiotherapy (SBRT) are increasingly used in the treatment of centrally located, early-stage non-small cell lung cancer (NSCLC), though there are concerns of increased morbidity and mortality in patients with ultracentral tumors (UC). We report on the long-term toxicity of patients with UC lung cancer treated on a prospective randomized clinical trial of SBRT versus conventionally hypofractionated radiotherapy (CRT) for stage I NSCLC (NCT01968941).

MATERIALS/METHODS

Patients with UC tumors, defined as those where the planning target volume directly overlaps with the proximal bronchial tree (PBT), were identified from the larger cohort of patients treated on the trial. These patients received either SBRT with 60 Gy in 8 fractions or CRT with 60 Gy in 15 fractions. The primary endpoint of this secondary analysis was development of any grade 3 or higher toxicity defined using CTCAE version 3.0. Secondary endpoints included local control, as well as dosimetric analysis of the PBT, using EQD2 with α/β ratio of 3 to assess the relationship between dose to the PBT and toxicity.

RESULTS

Twenty-nine patients were identified with UC tumors; 21 received SBRT and 8 received CRT. Median age was 72 years (range 55-88 years) and 59% were female. Median FEV1 was 1.46L (range 0.64-2.37L). Patients had either T1 (59%) or T2 (41%) lesions, with median tumor size 2.5cm (range 1.1-4.9cm). Most patients had histologically confirmed disease (squamous cell, n = 10; adenocarcinoma, n = 8; radiographically suspicious, n = 11). The median follow-up was 2.9 years (range 0.7-5.2 years). The 3-year local control rate of all patients was 88.3% (95% confidence interval: 75.7-100%). There were 3 patients with late (>3 months) grade 3 toxicity (bronchial stricture, chest pain, and atelectasis) and 1 patient with late grade 5 toxicity (bleeding/hemorrhage), all treated in the SBRT arm. Median EQD2 dose to PBT in patients with grade ≥3 late toxicity compared to the rest of the cohort was: Dmax, 132 vs 129 Gy; D0.1cc, 129 vs 119 Gy; D1cc, 124 vs 80 Gy; and D5cc, 83 vs 41 Gy. Median EQD2 volumetric doses in grade ≥3 patients (compared to the rest) to PBT were: V65 Gy, 9.7 vs 2.2cc; V80 Gy, 7.9 vs 1.1cc; V90 Gy, 6.2 vs 0.4cc; and V100 Gy, 4.8 vs 0.3cc. The single patient with grade 5 toxicity had the highest D5cc (116 Gy) and V100 Gy (7cc) among all patients.

CONCLUSION

Stereotactic radiation with 60 Gy in 8 fractions for UC lung cancer provides good local control but carries an approximately 15-20% rate of late grade ≥3 toxicity. There appears to be a dosimetric association between toxicity and dose to the PBT. It may be more important to minimize volumetric PBT dose rather than maximum point dose to reduce risk of severe late toxicity.

Molecular Status Predicts for Local Control in Patients with Non-Small Cell Lung Cancer Spinal Metastases Following Spine Stereotactic Body Radiotherapy

PURPOSE/OBJECTIVE(S)

We report outcomes after spine stereotactic body radiotherapy (SBRT) in patients with metastatic non-small cell lung cancer (NSCLC), to determine the significance of programmed death-ligand 1 (PD-L1) status and epidermal growth factor (EGFR) mutation on local failure (LF) rate.

MATERIALS/METHODS

A total of 165 patients and 389 spinal segments were retrospectively reviewed from 2009 to 2021. Baseline patient characteristics, treatment and outcomes were abstracted. Primary endpoint was LF and secondary outcomes included overall survival (OS) and vertebral compression fracture (VCF) rates. OS was estimated using the Kaplan-Meier method. Cumulative LF and VCF rates were calculated using competing risk analysis method. Multivariable analysis (MVA) evaluated factors predictive of LF and VCF.

RESULTS

Median follow-up was 13 months (range, 0.5-95 months). Median OS was 18.4 months (95% CI 11.4-24.6). Median age was 67 years (range, 28.2-89.9). 52% were female, 76% had an adenocarcinoma histology and 61% had a smoking history. 49/165 (29%) had an EGFR mutation. PD-L1 status was analyzed in 109/165 (66%) patients with 16% PD-L1 ≥ 50%, 20% PD-L1 1-49% and 35% PD-L1 <1%. Of 389 segments, 79% were de novo and 21% were previously radiated. At baseline, 35% had a VCF, 27% had epidural disease, 27% had paraspinal extension, and 49% were Spinal Instability in Neoplasia Score (SINS) stable. 239/389 (61%) were treated with either 24 or 28 Gy in 2 SBRT fractions. Within 1 month of SBRT, 39/165 (24%) had a tyrosine kinase inhibitor, 27/165 (16%) immunotherapy (IO) with or without chemotherapy, and 31/165 (19%) chemotherapy alone. LF cumulative incidence at 1- and 2-years was 16.3% (95% CI 12.8-20.3%) and 25.4% (95% CI 20.9%-30%), respectively. EGFR positivity (p<0.0001), PD-L1≥50% (p = 0.013) and treatment with IO within 1 month of SBRT (p = 0.004) predicted for improved local control on MVA. The 1- and 2-year LF rate in EGFR-positive vs. negative patients were 12.9% vs. 16.6% and 17.7% vs. 28.8%, respectively, and in those PD-L1 ≥50% vs PD-L1<50% were 7.8% vs. 19.6% and 7.8% vs. 38.1% respectively. Cumulative incidence of VCF at 1- and 2-years were 6.6% (95% CI 4.4-9.4%) and 8.8% (95% CI 6.1-12.0%). MVA identified prior SBRT to the same treated segment (P<0.0001) and a baseline VCF (p<0.0001) as significant predictors. 18/389 (4.6%) had radiation-induced radiculopathy and no radiation myelopathy events detected.

CONCLUSION

We identify the predictive utility of EGFR mutation and PD-L1 ≥50% status on local control in NSCLC patients with spinal metastases treated with spine SBRT, and a therapeutic benefit with peri-SBRT IO.

Outcomes for oligometastatic head and neck cancer treated with stereotactic body radiotherapy: Results from an international multi-institutional consortium

BACKGROUND

We report the results of an international multi-institutional cohort of oligometastatic (OMD) head and neck cancer (HNC) patients treated with SBRT.

METHODS

Patients with OMD HNC (≤5 metastases) treated with SBRT between 2008 and 2016 at six institutions were included. Treated metastasis control (TMC), progression-free survival (PFS), and overall survival (OS) were analyzed by multivariable analysis (MVA).

RESULTS

Forty-two patients with 84 HNC oligometastases were analyzed. The TMC rate at 1 and 2 years were 80% and 66%, with a median time to recurrence of 10.1 months. The median PFS and OS were 4.7 and 23.3 months. MVA identified a PTV point maximum (BED)10 > 100 Gy as a predictor of improved TMC (HR = 0.31, p = 0.034), and a cumulative PTV > 48 cc as having worse PFS (HR = 2.99, p < 0.001).

CONCLUSION

Favorable TMC and OS was observed in OMD HNCs treated with SBRT.

5-Year Renal Function Outcomes after SABR for Primary Renal Cell Carcinoma: A Report from the International Radiosurgery Oncology Consortium of the Kidney (IROCK)

PURPOSE/OBJECTIVE(S)

Renal cell carcinoma (RCC) presents uncommonly in patients with a congenital solitary kidney or prior contralateral nephrectomy. The objective of this study was to compare renal function outcomes of stereotactic ablative body radiotherapy (SABR) in patients with solitary vs. bilateral kidneys.

MATERIALS/METHODS

Patients with primary RCC with ≥2 years of follow-up at 12 participating International Radiosurgery Consortium for Kidney (IROCK) institutions were included. Patients with upper tract urothelial carcinoma or metastatic disease were excluded. Renal function was measured by estimated glomerular filtration rate (eGFR). For patients where eGFR was not recorded, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was used to estimate eGFR based on known creatinine. Baseline characteristics and renal function outcomes were compared between solitary vs. bilateral kidneys. Multivariable logistic regression was used to identify factors predictive of eGFR decline ≥ 15 mL/min and any eGFR increase evaluated at 1-year post-SABR.

RESULTS

One hundred and ninety patients with solitary (n = 56) or bilateral kidneys (n = 134) underwent SABR and were followed for a median of 5.0 years (IQR: 3.4-6.8). Pre-SABR eGFR (mean ± SD) was similar in patients with solitary (61.1 ± 23.2 mL/min) vs. bilateral kidneys (58.0 ± 22.3 mL/min, p = 0.324). Mean tumor size was 3.70 ± 1.40 cm in solitary and 4.35 ± 2.50 cm in bilateral kidneys (p = 0.026). After SABR, an initial compensatory increase in eGFR was observed in both cohorts (22.7% solitary and 17.7% bilateral at 1 year). This compensatory increase persisted in patients with bilateral but not a solitary kidney (10.3% vs. 0% at 3-years and 21.1% vs. 0% at 5-years, respectively). At 5-years post-SABR, eGFR decreased by -14.5 ± 7.6 in solitary and -13.3 ± 15.9 mL/min in bilateral kidneys (p = 0.665). At all timepoints assessed, there were no significant differences in eGFR decline between solitary vs. bilateral cohorts (all p > 0.05). There were also no significant differences in post-SABR end-stage renal disease (7.1% vs. 6.7%) or dialysis (3.6% vs. 3.7%) in solitary vs. bilateral, respectively. Multivariable analysis demonstrated that increasing tumor size (OR per 1 cm: 1.57; 95% CI: 1.14-2.16, p = 0.006) and baseline eGFR (OR per 10 mL/min: 1.30; 95% CI: 1.02-1.66, p = 0.034) was more likely to be associated with eGFR decline ≥ 15 mL/min. There was no significant association between solitary vs. bilateral kidney and eGFR decline (OR: 1.22; 95% CI: 0.45-3.34, p = 0.693).

CONCLUSION

There was no observed difference between renal function outcomes in patients with a solitary vs. bilateral kidneys. While larger tumor size may increase the risk of eGFR decline post-SABR, treatment of a solitary kidney does not appear to increase the risk of renal dysfunction long-term.

Safety and Efficacy of Stereotactic Body Radiotherapy for Ultra-Central Thoracic Tumors

PURPOSE/OBJECTIVE(S)

Stereotactic body radiotherapy (SBRT) is increasingly utilized in the management of ultra-central thoracic tumors, although concerns regarding significant toxicity remain. We sought to evaluate the toxicity and efficacy of SBRT to these tumors at our institution.

MATERIALS/METHODS

Patients with ultra-central lung tumors or nodes treated at our institution with SBRT between 2009 and 2019 were retrospectively reviewed. Ultra-central was defined as having the planning target volume (PTV) overlapping or abutting the central bronchial tree and/or esophagus. All SBRT plans were generated with homogenous dose distributions using target coverage objectives of ITV V100% >99%, PTV V95% >99%, and an ideal PTV Dmax <105% (strict <120%). All plans were reviewed in quality assurance rounds by a team of dosimetrists, physicists, and radiation oncologists. The primary endpoint was incidence of severe toxicity (ST), defined as SBRT-related grade ≥3 toxicities, graded using the Common Terminology Criteria for Adverse Events V5.0. Secondary endpoints included local failure (LF), progression-free survival (PFS) and overall survival (OS). Competing risk analysis was used to estimate incidence and predictors of ST and LF, with death as a competing risk. Kaplan-Meier method was used to estimate PFS and OS.

RESULTS

A total of 154 patients who received 162 ultra-central courses of SBRT were included, with a median follow-up of 21.5 months. Treatment intent was most commonly for oligoprogression (46%), oligometastasis (30%), followed by curative (20%). The most frequent tumor histologies were NSCLC (41%) and RCC (26%). SBRT prescription doses ranged from 30-55 Gy in 5 fractions (BED10 range 48-115 Gy). The most common prescription was 50 Gy in 5 fractions (42%). The cumulative incidence of ST was 8.9% at 3-years. The most common ST was pneumonitis (n = 4). Notable toxicities included bronchopleural fistula (n = 2, grade 3 and 4), bronchial stricture (n = 1, grade 3), and esophagitis leading to bleeding (n = 1, grade 4). There were no esophageal strictures or perforations, and no bronchial bleeds. There was 1 possible treatment related death from pneumonitis/pneumonia. Predictors of any ST included increased lung V5 Gy, decreased PTV V95%, and not having prior radiation therapy to the chest. The cumulative incidence of LF was 4.8%, 11% and 14% at 1-, 2-, and 3-years respectively. Predictors of LF included younger age, and greater volume of overlap between the PTV and esophagus. Median PFS was 8.4 months, while median OS was 3.7 years.

CONCLUSION

In one of the largest case series of ultra-central thoracic SBRT reported to date, homogenously prescribed SBRT plans were associated with relatively low rates of ST and LF across a variety of treatment indications. Predictors of ST should be interpreted recognizing the heterogeneity in toxicities observed. Identified predictors of both ST and LF can contribute to future work to optimize the therapeutic ratio in treatment of ultra-central thoracic tumors.