Extra-thoracic tumor burden but not thoracic tumor burden on (18)F-FDG PET/CT is an independent prognostic biomarker for extensive-disease small cell lung cancer

Lung Cancer. 2013 Aug;81(2):218-25. doi: 10.1016/j.lungcan.2013.05.001. Epub 2013 May 31.

Abstract

Purpose: The aim of this study was to evaluate the relationship and difference in prognostic significance between whole-body tumor burden, thoracic tumor burden, and extra-thoracic tumor burden on (18)F-FDG PET/CT for patients with extensive-disease small cell lung cancer (ED-SCLC).

Materials and methods: We performed a retrospective, two-center analysis for patients with ED-SCLC who underwent pretreatment (18)F-FDG PET/CT. Metabolic tumor burden was estimated using whole-body metabolic tumor volume (MTV(WB)), thoracic metabolic tumor volume (MTV(TRX)), extra-thoracic metabolic tumor volume (MTV(EXT)), and the number of extra-thoracic tumor foci. Uni- and multivariate analyses were performed using various clinical factors and the metabolic indices.

Results: A total of 91 patients were eligible for this study. MTV(WB) showed stronger correlation with MTV(EXT) than MTV(TRX) (r(2) = 0.804 vs. 0.132, p < 0.001, both), whereas no correlation was observed between MTV(EXT) and MTV(TRX) (r(2) = 0.007, p = 0.428). Patients with smaller MTV(WB), MTV(EXT), and extra-thoracic tumor foci showed longer survival than patients with larger MTV(WB), MTV(EXT), and extra-thoracic tumor foci, respectively, whereas the survival difference between patients with smaller MTV(TRX) and those with larger MTV(TRX) was not significant. Results of uni- and multivariate analyses showed that ECOG performance status (HR = 2.31, p = 0.015), initial chemotherapy cycles (HR = 0.24, p < 0.001), and the number of extra-thoracic tumor foci (HR = 2.75, p < 0.001) were independent prognostic factors for overall survival, and initial chemotherapy cycles (HR = 0.25, p < 0.001), and MTV(EXT) (HR = 2.04, p = 0.013) were independent prognostic factors for progression-free survival.

Conclusion: These data provide evidence indicating that extra-thoracic tumor burden but not thoracic tumor burden is an independent prognostic biomarker for ED-SCLC, and support further exploration of novel treatment strategies targeting extra-thoracic tumor burden in order to improve the clinical outcomes of patients with ED-SCLC.

Keywords: (18)F-FDG PET/CT; Biomarker; Extensive disease small cell lung cancer; Metabolic tumor volume; Oligometastases; Prognosis.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Disease-Free Survival
  • Female
  • Fluorodeoxyglucose F18
  • Humans
  • Lung Neoplasms / diagnosis*
  • Lung Neoplasms / diagnostic imaging*
  • Lung Neoplasms / pathology
  • Male
  • Middle Aged
  • Positron-Emission Tomography / methods
  • Prognosis
  • Radiopharmaceuticals
  • Retrospective Studies
  • Small Cell Lung Carcinoma / diagnosis*
  • Small Cell Lung Carcinoma / diagnostic imaging*
  • Small Cell Lung Carcinoma / pathology
  • Thoracic Neoplasms / diagnosis*
  • Thoracic Neoplasms / diagnostic imaging*
  • Thoracic Neoplasms / pathology
  • Tomography, X-Ray Computed / methods
  • Tumor Burden

Substances

  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18