PET-detected pneumonitis following curative-intent chemoradiation in non-small cell lung cancer (NSCLC): recognizing patterns and assessing the impact on the predictive ability of FDG-PET/CT response assessment

Amir Iravani, Guy Anne Turgeon, Tim Akhurst, Jason W. Callahan, Mathias Bressel, Sarah J. Everitt, Shankar Siva, Michael S. Hofman, Rodney J. Hicks, David L. Ball, Michael P. Mac Manus

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Purpose: Inflammatory FDG uptake in the lung (PET-pneumonitis) following curative-intent radiotherapy (RT)/chemo-RT (CRT) in non-small cell lung cancer (NSCLC) can pose a challenge in FDG-PET/CT response assessment. The aim of this study is to describe different patterns of PET-pneumonitis to guide the interpretation of FDG-PET/CT and investigate its association with tumor response and overall survival (OS). Methods: Retrospective analysis was performed on 87 NSCLC patients in three prospective trials who were treated with radical RT (n = 7) or CRT (n = 80), with baseline and post-treatment FDG-PET/CT. Visual criteria were performed for post-treatment FDG-PET/CT response assessment. The grading of PET-pneumonitis was based on relative lung uptake intensity compared to organs of reference and classified as per Deauville score from grade 1–5. Distribution patterns of PET-pneumonitis were defined as follows: A) patchy/sub-pleural; B) diffuse (involving more than a segment); and C) peripheral (diffusely surrounding a photopenic region). Results: Follow-up FDG-PET/CT scans were performed approximately 3 months (median, 89 days; interquartile range, 79–93) after RT. Overall, PET-pneumonitis was present in 62/87 (71%) of patients, with Deauville 2 or 3 in 12/62 (19%) and 4 or 5 in 50/62 (81%) of patients. The frequency of patterns A, B and C of PET-pneumonitis was 19/62 (31%), 20/62 (32%) and 23/62 (37%), respectively. No association was found between grade or pattern of PET-pneumonitis and overall response at follow-up PET/CT (p = 0.27 and p = 0.56, respectively). There was also no significant association between PET-pneumonitis and OS (hazard ratio [HR], 1.3; 95% confidence interval [CI], 0.6–2.5; p = 0.45). Early FDG-PET/CT response assessment, however, was prognostic for OS (HR, 1.7; 95% CI, 1.2–2.2; p < 0.001). Conclusion: PET-pneumonitis is common in early post-CRT/RT, but pattern recognition may assist in response assessment by FDG-PET/CT. While FDG-PET/CT is a powerful tool for response assessment and prognostication, PET-pneumonitis does not appear to confound early response assessment or to independently predict OS.

Original languageEnglish
Pages (from-to)1869-1877
Number of pages9
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume46
Issue number9
DOIs
StatePublished - Aug 1 2019

Keywords

  • FDG-PET/CT
  • Non-small cell lung cancer (NSCLC)
  • PET response assessment
  • PET-pneumonitis
  • Radiation pneumonitis

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