Areas of High 18F-FDG Uptake on Preradiotherapy PET/CT Identify Preferential Sites of Local Relapse After Chemoradiotherapy for Non–Small Cell Lung Cancer

Journal of Nuclear Medicine

Sébastien Thureau¹  Luc Thiberville¹  Bernard Dubray¹  Isabelle Gardin¹  Jérémie Calais¹  Romain Modzelewski¹  Pierre Vera¹ 

关键词: ¹⁸F-FDG PET/CT;    lung cancer;    radiotherapy;    target volume;    ¹⁸F-FDG uptake;    local relapse;   

DOI  :  10.2967/jnumed.114.144253

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

The high rates of failure in the radiotherapy target volume suggest that patients with stage II or III non–small cell lung cancer (NSCLC) should receive an increased total dose of radiotherapy. Areas of high 18F-FDG uptake on preradiotherapy 18F-FDG PET/CT have been reported to identify intratumor subvolumes at high risk of relapse after radiotherapy. We wanted to confirm these observations on a cohort of patients included in 3 sequential prospective studies. Our aim was to assess an appropriate threshold (percentage of maximum standardized uptake value [SUVmax]) to delineate subvolumes on staging 18F-FDG PET/CT scans assuming that a smaller target volume would facilitate isotoxic radiotherapy dose escalation. Methods: Thirty-nine patients with inoperable stage II or III NSCLC, treated with chemoradiation or with radiotherapy alone, were extracted from 3 prospective studies (ClinicalTrials.gov identifiers NCT01261585, NCT01261598, and RECF0645). All patients underwent 18F-FDG PET/CT at initial staging, before radiotherapy, during radiotherapy, and during systematic follow-up in a single institution. All 18F-FDG PET/CT acquisitions were coregistered on the initial scan. Various subvolumes in the initial acquisition (30%, 40%, 50%, 60%, 70%, 80%, and 90% SUVmax thresholds) and in the 3 subsequent acquisitions (40% and 90% SUVmax thresholds) were pasted on the initial scan and compared. Results: Seventeen patients had a local relapse. The SUVmax measured during radiotherapy was significantly higher in locally relapsed tumors than in locally controlled tumors (mean, 6.8 vs. 4.6; P = 0.02). The subvolumes delineated on initial PET/CT scans with 70%–90% SUVmax thresholds were in good agreement with the recurrent volume at a 40% SUVmax threshold (common volume/baseline volume, 0.60–0.80). The subvolumes delineated on initial PET/CT scans with 30%–60% SUVmax thresholds were in good to excellent agreement with the core volume of the relapse (90% SUVmax threshold) (common volume/recurrent volume and overlap fraction indices, 0.60–0.93). The agreement was moderate (>0.51) when a 70% SUVmax threshold was used to delineate on initial PET/CT scans. Conclusion: High 18F-FDG uptake areas on pretreatment PET/CT scans identify tumor subvolumes at greater risk of relapse in patients with NSCLC treated by concomitant chemoradiation. We propose a 70% SUVmax threshold to delineate areas of high 18F-FDG uptake on initial PET/CT scans as the target volumes for potential radiotherapy dose escalation.

【 授权许可】

Unknown