18F-Fludeoxyglucose PET/CT in SCLC: Analysis of the CONVERT Randomized Controlled Trial

Prakash Manoharan,Ahmed Salem,Hitesh Mistry,Michael Gornall,Susan Harden,Peter Julyan,Imogen Locke,Jonathan Mcaleese,Rhona Mcmenemin,Nazia Mohammed,Michael Snee,Sarah Woods,Thomas Westwood,Corinne Faivre-Finn

doi:10.1016/j.jtho.2019.03.023

Abstract

IntroductionWe used phase-3 CONVERT trial data to investigate the impact of fludeoxyglucose F 18 (18F-FDG) positron emission tomography (PET)/computed tomography (CT) in SCLC. MethodsCONVERT randomized patients with limited-stage SCLC to twice-daily (45 Gy in 30 fractions) or once-daily (66 Gy in 33 fractions) chemoradiotherapy. Patients were divided into two groups in this unplanned analysis: those staged with conventional imaging (contrast-enhanced thorax and abdomen CT and brain imaging with or without bone scintigraphy) and those staged with 18F-FDG PET/CT in addition. ResultsData on a total of 540 patients were analyzed. Compared with patients who underwent conventional imaging (n = 231), patients also staged with 18F-FDG PET/CT (n = 309) had a smaller gross tumor volume (p = 0.003), were less likely to have an increased pretreatment serum lactate dehydrogenase level (p = 0.035), and received more chemotherapy (p = 0.026). There were no significant differences in overall (hazard ratio = 0.87, 95% confidence interval: 0.70–1.08, p = 0.192) and progression-free survival (hazard ratio = 0.87, 95% confidence interval: 0.71–1.07], p = 0.198) between patients staged with or without 18F-FDG PET/CT. In the conventional imaging group, we found no survival difference between patients staged with or without bone scintigraphy. Although there were no differences in delivered radiotherapy dose, 18F-FDG PET/CT–staged patients received lower normal tissue (lung, heart, and esophagus) radiation doses. Apart from a higher incidence of late esophagitis in patients staged with conventional imaging (for grade ≥1, 19% versus 11%; [p = 0.012]), the incidence of acute and late radiotherapy-related toxicities was not different between the two groups. ConclusionIn CONVERT, survival outcomes were not significantly different in patients staged with or without 18F-FDG PET/CT. However, this analysis cannot support the use or omission of 18F-FDG PET/CT owing to study limitations.

Highlights

We used phase-3 CONVERT trial data to investigate the impact of fludeoxyglucose F 18 (18F-FDG) positron emission tomography (PET)/computed tomography (CT) in SCLC
In CONVERT, survival outcomes were not significantly different in patients staged with or without 18F-FDG PET/CT. This analysis cannot support the use or omission of 18F-FDG PET/CT owing to study limitations
The modified intention-to-treat survival analysis in CONVERT included 543 patients, of whom 540 with data on staging investigations were eligible for this analysis

Summary

Introduction

We used phase-3 CONVERT trial data to investigate the impact of fludeoxyglucose F 18 (18F-FDG) positron emission tomography (PET)/computed tomography (CT) in SCLC. Devised by the Veterans Administration Lung Cancer Study, this system classifies SCLC into limited- or extensive-stage disease according to whether the tumor is localized to one hemithorax.[4] In 2009, the Union for International Cancer Control/American Joint Committee on Cancer, based on an analysis by the International Association for the Study of Lung Cancer, recommended the use of TNM staging in SCLC, as it provides additional prognostic information.[5] This recommendation was recently confirmed in a CONVERT trial subgroup analysis.[6] Treatment and outcome vary according to stage, highlighting the importance of accurate staging in SCLC to guide therapeutic decisions and provide prognostication. The addition of atezolizumab to chemotherapy was recently shown to improve survival in the first-line setting.[13]

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Results

Conclusion