Author of

• 12544

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  P3.08 - Poster Session 3 - Radiotherapy (ID 199)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 12547

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    P3.08-003 - FDG-PET parameters as predictors for outcome in Non Small Cell Lung Cancer NSCLC treated with Stereotactic Ablative Radiotherapy (SABR) at the St James's Institute of Oncology (ID 771)

    09:30 - 09:30  |  Author(s): M. Subesinghe
    • Abstract

    Background
    Background: To identify predictive FDG-PET imaging factors for outcomes following Stereotactic Ablative Radiotherapy in early stage Non Small Cell Lung Cancer

    Methods
    Patients with inoperable T1 and T2 NSCLC and a baseline FDG PET-CT at a single centre (St James Institute of Oncology) treated with SABR for a single tumour between 2009 and 2012 were included. Prospective data was collected on a range of FDG-PET parameters (Tumour SUVmean, SUVmax, Tumour:Liver SUVmax and SUVmean ratios, Tumour:Mean Blood Pool SUVmax and SUVmean ratios and TLG –Total lesion glycolysis). Patient characteristics and outcome variables including stage, histology, PTV volume, performance status, dose, time interval between PET and SABR, response to treatment and patterns of failure collected and analysed. The PET parameters were analysed initially as a continuous variable.

    Results
    125 patients (72 female, 53 male), median age 75, 94 were T1 and 31 T2. Median follow-up 1.2yrs (range 0.28-3.3). Histology confirmation was possible in 40 patients. Relapse free survival at 2 years was 55%. Local (LR), regional (RR) and distant relapse (DR)-free rates were 94%, 89% and 83% respectively. Overall (OS) and cause-specific survival at 2 years was 57% and 81% respectively. On multivariate analysis, pre-treatment SUVmax was the only PET parameter that consistently predicted for recurrence (p<0.01), DR (p=0.012) and OS (p=0.026). This was consistent amongst patients with and without diagnostic pathology and no statistical difference was found between the two groups. Patients with SUVmax > 17.9 had significantly worse DR and OS (HR 9.99 and 6.68 respectively). SUVmax however did not correlate with LR or RR rates. The only other PET parameter with any statistically significant correlation was the TLG20 which showed some association with RR (p=0.038). Once SUVmax was established as the strongest predictor for outcome this was assessed as a dichotomised variable to assess predictability for DR. Patients with an SUVmax above17.9 were found to have significantly higher rates of DR (p=0.03)

    Conclusion
    In our population SUVmax is the strongest FDG-PET parameter to correlate with outcome following SABR for NSCLC. Number of events of DR were small and a cut off point predicting for this is difficult to interpret. This is consistent with previously published data. With SABR an emerging treatment modality for early stage disease, this may have future implications on the use of adjuvant chemotherapy.