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

Effect of histology on stereotactic body radiotherapy for non-small cell lung cancer oligometastatic pulmonary lesions

Background

Stereotactic body radiotherapy (SBRT) is commonly used to provide targeted treatment to metastatic lung disease. Investigation is needed to understand the influence of histology on treatment outcomes. We report how tumor histology affects local control (LC) in a cohort of patients with non-small cell lung cancer (NSCLC) receiving SBRT for oligometastatic and recurrent pulmonary lesions.

Methods

Patients who received SBRT to recurrent or oligometastatic NSCLC pulmonary lesions from 2015-2019 at our institution were included in this retrospective cohort study. Minimum follow-up was 2 months. Kaplan-Meier (KM) analysis was performed to assess local progression-free survival (LPFS). Local failure cumulative incidence curves using death as a competing risk factor were also generated.

Results

A total of 147 treated lesions from 83 patients were included: 95 lesions from 51 patients with lung adenocarcinoma and 52 lesions from 32 patients with lung squamous cell carcinoma (SqCC). Median follow-up was 23 [interquartile range (IQR): 9.5-44.5] months for adenocarcinoma, and 11.5 (6-32.25) months for SqCC. Two-year LC was 89% for adenocarcinoma and 77% for SqCC (P=0.04). Median overall survival (OS) was 24.5 (10-46.25) months for adenocarcinoma and 14.5 (7.75-23.25) months for SqCC. Adenocarcinoma had improved LPFS over SqCC (P=0.014). SqCC was associated with increased local failure risk that approached statistical significance (P=0.061) with death as a competing risk. Overall toxicity incidence was 8.2% with no G3+ toxicities.

Conclusions

For SBRT-treated oligometastatic or recurrent NSCLC pulmonary lesions, adenocarcinoma histology is associated with improved 2-year LC and LPFS compared to SqCC and reduced incidence of local recurrence (LR) with death as a competing risk.

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

Simple Summary

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

Abstract

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