ESTRO ACROP consensus guideline on implementation and practice of stereotactic body radiotherapy for peripherally located early stage non-small cell lung cancer

Abstract

Background

Stereotactic body radiotherapy (SBRT) has become the standard of care for medically inoperable patients with peripherally located, early stage non-small cell lung cancer (NSCLC), and for those refusing surgical resection. Despite the availability of national and international guidelines, there exists substantial variability in many aspects of SBRT practice.

Methods

The ESTRO ACROP guideline is based on a questionnaire covering all aspects of SBRT implementation and practice (n = 114 items). The questionnaire was answered by the 11 faculty members of the ESTRO course “Clinical practice and implementation of image-guided SBRT” and their 8 institutions.

Results

Agreement by >50% of the institutions was achieved in 72% of all items. Only 8/57 technologies and techniques were identified as mandatory for SBRT while 32/57 were considered as optional. In contrast, quality-assurance related elements were considered as mandatory in 12/24 items. A consensus of risk-adapted SBRT fractionation was achieved with 3 × 15 Gy for peripherally located lesions and 4 × 12 Gy (PTV D95-D99; D_max <125% to <150%) for lesions with broad chest wall contact. For patients free from severe comorbidities and with favourable long-term OS expectancy, use of the maximum tolerated dose of 3 × 18 Gy should be considered.

Conclusions

This ACROP guideline achieved detailed recommendations in all aspects of SBRT implementation and practice, which will contribute to further standardization of SBRT for peripherally located early stage NSCLC.

Introduction

Stereotactic body radiotherapy (SBRT) has become the standard of care for patients with medically inoperable early stage non-small cell lung cancer (NSCLC), and for those refusing surgical resection [1]. International, multi-disciplinary guidelines (ESMO, NCCN) support the superiority of SBRT over conventionally fractionated radiotherapy, and SBRT is preferred to other ablative methods [2], [3], [4]. As a consequence, SBRT for early stage NSCLC is today practiced by the majority of radiotherapy centers in Europe, Canada and the US [5], [6], [7], [8].

Despite the availability of multi-disciplinary guidelines recommending SBRT as the standard of care, and despite rapid and broad adoption of SBRT within the radiotherapy community, there exists substantial variability in many aspects of SBRT [9], [10], [11]. Such variations are observed in patient selection, staging, equipment used and methodology of SBRT planning and delivery, quality assurance and patient follow-up schedules. This lack of standardization can be explained by several factors and their interactions [12]: (1) rapid developments in new radiotherapy technologies; (2) lack of large scale studies comparing different workflows, procedures and devices; (3) adaptation of SBRT practice to the local situation and available equipment; 4) lack of comprehensive guidelines.

Several guidelines have been published by national and international bodies aiming to standardize and homogenize the practice of SBRT for early stage NSCLC: American Society for Radiation Oncology (ASTRO) and American College of Radiology (ACR) on image-guided radiotherapy and SBRT in general [13], [14]; European Organisation for Research and Treatment of Cancer (EORTC) on high precision radiotherapy [15]; American Association of Physicists in Medicine (AAPM) on SBRT in general [16]; UK National Radiotherapy Implementation Group Report on implementation of SBRT in general [17]; Canadian Association of Radiation Oncology (CARO) on practice guideline for lung, liver and spine SBRT [18]; German Society for Radiotherapy and Oncology (DEGRO) on SBRT practice for early stage NSCLC [19]; and Canadian Comité de l’évolution des pratiques en oncologie (CEPO) on SBRT for early stage NSCLC [20].

This Advisory Committee on Radiation Oncology Practice (ACROP) Guideline on SBRT for peripherally located early stage NSCLC aims to address unmet needs in current practice guidelines in radiation oncology. Co-authors of this guideline are faculty members of the European Society for Radiotherapy and Oncology (ESTRO) teaching course “Clinical practice and implementation of image-guided SBRT”, and were motivated by the needs and questions of course participants especially in areas where variations in practice exist and strong evidence is lacking. Radiation oncologists and medical physicists contributed equally and comprehensively to the development of this multi-professional practice guideline.

It is evident that the therapeutic ratio of SBRT is favorable despite the observed variations in clinical practice. Nevertheless, we believe that this guideline is worthwhile for several reasons: (1) setting minimum requirements may ensure consistent clinical outcomes as the use of SBRT continues to expand; (2) the availability of minimum requirements may facilitate a more rapid adoption of SBRT; (3) result in SBRT practice being more efficient, and thus cost effective; (4) decreased variability of SBRT will improve comparability of outcome between different protocols and studies.