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J Nucl Med. 2015 Feb;56(2):196-203. doi: 10.2967/jnumed.114.144253. Epub 2015 Jan 8.

Areas of high 18F-FDG uptake on preradiotherapy PET/CT identify preferential sites of local relapse after chemoradiotherapy for non-small cell lung cancer.

Author information

1
Nuclear Medicine Department, Henri Becquerel Cancer Center and Rouen University Hospital, Rouen, France QuantIF-LITIS (EA [Equipe d'Accueil] 4108-FR CNRS [Fédération de Recherche-Centre National pour la Recherche Scientifique] 3638), Faculty of Medicine, University of Rouen, Rouen, France.
2
Nuclear Medicine Department, Henri Becquerel Cancer Center and Rouen University Hospital, Rouen, France QuantIF-LITIS (EA [Equipe d'Accueil] 4108-FR CNRS [Fédération de Recherche-Centre National pour la Recherche Scientifique] 3638), Faculty of Medicine, University of Rouen, Rouen, France Department of Radiotherapy and Medical Physics, Henri Becquerel Cancer Centre and Rouen University Hospital, Rouen, France; and.
3
QuantIF-LITIS (EA [Equipe d'Accueil] 4108-FR CNRS [Fédération de Recherche-Centre National pour la Recherche Scientifique] 3638), Faculty of Medicine, University of Rouen, Rouen, France Department of Radiotherapy and Medical Physics, Henri Becquerel Cancer Centre and Rouen University Hospital, Rouen, France; and.
4
QuantIF-LITIS (EA [Equipe d'Accueil] 4108-FR CNRS [Fédération de Recherche-Centre National pour la Recherche Scientifique] 3638), Faculty of Medicine, University of Rouen, Rouen, France Department of Pneumology, Rouen University Hospital, Rouen, France.
5
Nuclear Medicine Department, Henri Becquerel Cancer Center and Rouen University Hospital, Rouen, France QuantIF-LITIS (EA [Equipe d'Accueil] 4108-FR CNRS [Fédération de Recherche-Centre National pour la Recherche Scientifique] 3638), Faculty of Medicine, University of Rouen, Rouen, France pierre.vera@chb.unicancer.fr.

Abstract

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 (18)F-FDG uptake on preradiotherapy (18)F-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 (18)F-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 (18)F-FDG PET/CT at initial staging, before radiotherapy, during radiotherapy, and during systematic follow-up in a single institution. All (18)F-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 (18)F-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 (18)F-FDG uptake on initial PET/CT scans as the target volumes for potential radiotherapy dose escalation.

KEYWORDS:

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

PMID:
25572091
DOI:
10.2967/jnumed.114.144253
[Indexed for MEDLINE]
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