Author of

• 11890

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  P2.19 - Poster Session 2 - Imaging (ID 180)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Imaging, Staging & Screening
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11898

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    P2.19-008 - The prognostic value of tumor metabolic volume in PET-CT study for unresectable non-small-cell lung cancer treated with definite radiotherapy (ID 1190)

    09:30 - 09:30  |  Author(s): B. Bobek-Billewicz
    • Abstract

    Background
    Over the recent years, PET-CT studies have become the golden standard for the planning of high-dose definite radiotherapy of non-small-cell lung cancer (NSCLC). This is justified by their proven superiority over computer tomography in both sensitivity and specifity to determine the location of all tumor sites, helping avoid underirradiation of active malignancy as well as using unnecessarily large field sizes. Numerous reviews have pointed out that the quantifiers of tumor metabolism, primarily the maximal Standard Uptake Value (SUVmax) of [18]F-deoxyglucose as measured in PET-CT studies can as well serve as a prognostic factor in NSCLC. As we were expecting this to be particularily significant for patients with unresectable tumors yet irradiated with intention to cure, we decided to retrospectively investigate the prognostic value of tumor metabolism quantification for this group.

    Methods
    The material of our study consists of 53 patients, treated with definite radiotherapy (with sequential chemotherapy in 50 cases) for locally advanced, unresectable NSCLC. The doses prescribed for radiotherapy ranged from 60 to 71,2 Gy; all patients completed the intended radiation treatment. We assessed the tumor metabolism on PET-CT studies used for radiotherapy planning; in addition to measuring the SUVmax value, we quantified the tumor metabolic volume (TMV) using three different algorithms varying by the threshold above which voxels within the tumor were considered its volume. Results were co-related to various clinical parameters and the therapeutic outcome, measured as progression-free and overall survival at 36 months of follow-up.

    Results
    Figure 1 Of all clinical variables as well as the tumor metabolism quantifiers, the TMV was found to be the only standalone statistically significant prognostic factor for both overall (log-rank test p=0,048) and progression-free survival (p=0,014). Its value was confirmed in both Kaplan-Meier (shown) and Cox models. No co-relation was found between TMV and SUVmax, tumor type, sex or the pattern of failure. Tumor stage in PET-CT studies (after or during chemotherapy) was co-related to TMV, yet its prognostic value was not significant.

    Conclusion
    TMV is a simple parameter to calculate during routine analysis of PET-CT study, which provides - independently on the clinical variables and more accurately than radiological re-staging - relatively reliable prognostic information for patients who are to be treated with definite radiotherapy for NSCLC. Prospective studies on larger number of patients need to be undertaken to answer whether and how to alter the treatment regime (dose escalation, hypofractionation) in order to improve the outcome for patients with unfavorably high TMV.