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V.J. Nair



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    P1.08 - Poster Session 1 - Radiotherapy (ID 195)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Radiation Oncology + Radiotherapy
    • Presentations: 1
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      P1.08-027 - Is there a benefit of lung stereotactic ablative radiotherapy (SABR) in our patients with multiple co-morbidities?: Age-adjusted Charlson Comorbidity Index (ACCI) as a predictor of survival in medically inoperable early stage Non Small Cell Lung Cancer patients treated with definitive radiotherapy (ID 3392)

      09:30 - 16:30  |  Author(s): V.J. Nair

      • Abstract

      Background
      The Age-adjusted Charlson Comorbidity Index (ACCI) was originally developed as a tool to predict survival for a wide range of patients based on their co-morbidities. As a growing proportion of Stage I non-small cell lung cancer (NSCLC) patients are treated with radiotherapy alone, in part due to extensive comorbidities, we hypothesize that a) ACCI is a useful prognostic tool for this understudied group of patients and b) the advent of stereotactic ablative radiotherapy (SABR) has lead to a redistribution of patients such that more patients of the poorest class are now treated, with similar or better survival.

      Methods
      A single institution, ethics-approved database with outcome data for 406 Stage I NSCLC patients treated with curative radiotherapy alone from 2001 to 2011 was queried. 283 patients were treated with conventional radiotherapy and 123 with SABR. Conventional doses ranged from 50-60Gy over 15-30 fractions, SABR 48-60Gy over 3-8 fractions. For each patient the ACCI score was retrospectively calculated and then arbitrarily stratified into 3 groups based on score ( ≤3, 4-5, ≥6) (higher score indicates higher number of comorbidities). Log rank test and Kaplan-Meier survival analyses was performed and the relationship between ACCI and survival was assessed using proportional hazards analysis.

      Results
      Median follow up was 26.4 months (22.8 months in the SABR group). The median patient age at treatment was 75 (range 41 to 92) for the entire cohort and for the SABR subset 74 (range 54-89). Percentage of patients by ACCI grouping was 22% (≤3), 48% (4-5) and 30% (≥6) for the entire cohort and for the SABR subset was 21% (≤3), 59% (4-5) and 20% (≥6) (p> 0.05). The median overall survival (OS) from time of diagnosis was 39.6 months (95% CI 34.8-44.4) and by ACCI groupings (≤3, 4-5, ≥6) was 51.6, 39.6 and 30 months (log rank test p=0.023) with hazard ratios for survival of 1.00, 1.45 (p = 0.049) and 1.73 (p = 0.0067) respectively. In the subset of patients treated with SABR, median OS was 46.8 months however there is lack of power to demonstrate any OS difference between ACCI groups.

      Conclusion
      The ACCI is predictive of overall survival in medically inoperable Stage I NSCLC patients irradiated with curative intent. The benefit of radiation is evident in even the poorest of patients (CMI ≥6) with a median survival of 30 months exceeding what one would expect without any treatment at all. Further follow up will be required to comment on any increased benefit with SABR.

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    P2.12 - Poster Session 2 - NSCLC Early Stage (ID 205)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Medical Oncology
    • Presentations: 1
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      P2.12-023 - Pre-treatment 18FDG-PET SUV<sub>max </sub>As A Predictor of Distant Metastasis in Early Stage NSCLC Treated with Definitive Radiotherapy (ID 3442)

      09:30 - 16:30  |  Author(s): V.J. Nair

      • Abstract

      Background
      Positron emission tomography (PET) using [[18]F]-fluoro-2-deoxy-glucose (FDG) is a standard staging investigation for patients with non-small cell lung cancer (NSCLC). The maximum standardized uptake value (SUV~max~) is a semi-quantitative measure of FDG uptake that correlates with tumor doubling time and proliferation rates, which in turn are known to correlate with tumor aggressiveness. The aim of this study was to determine whether the pre-radiation SUV~max~ of the primary tumor for FDG has a prognostic significance in patients with T1 or T2N0 NSCLC treated with curative radiation therapy.

      Methods
      Between April 1993 and December 2011, a total of 406 patients with medically inoperable histologically proven T1 or T2N0 NSCLC treated with radiotherapy (either conventional fractionation or stereotactic ablative radiotherapy (SABR)) were entered in an ethics-approved database. Minimum radiation dose delivered was 50Gy. 180 tumors (163 patients) with pre-treatment FDG-PET/CT scan satisfied the eligibility criteria. We stratified the patients above and below the median SUV~max~ value on the pre-treatment PET/CT scan and analysed the survival data, measured from date of diagnosis. Statistical analysis (including multivariate) was done using SPSS v15. Survival data was analysed using Kaplan-Meier method, and comparisons of survival were done using Mantel-Cox log-rank test.

      Results
      Of the 180 tumors, 68.9 % were T1; 24.6% centrally located (RTOG definition); 64.4% of treated with SABR. Median follow-up time was 15 months. Overall survival (OS) at 2 and 3 years for the entire cohort was 76% and 67% respectively. Mean and median SUVmax were 8.1 and 7 respectively. Progression free survival at 3 years with SUVmax < 7 was approximately double that of those patients with tumor SUVmax ≥ 7 (55% vs. 28%; p=0.0096). Tumors with SUVmax ≥ 7 were associated with a worse regional recurrence free survival but no difference was seen for local recurrence. In the multivariate analysis SUVmax≥7 was an independent prognostic factor for distant metastasis free survival (DMFS) [Figure 1], in addition to a higher T status being an independent prognostic factor for worse overall survival. Figure 1: Results of univariate and multivariate analysis demonstrating the prognostic factors associated with DMFS Figure 1

      Conclusion
      In early stage NSCLC managed with radiation alone, patients with high SUV~max~ ≥7 on FDG-PET/CT scan have poorer outcomes and high risk of progression, possibly due to aggressive biology. Pre-treatment FDG-PET/CT is an effective and non-invasive method to identify patients with higher risk of distant metastasis and possible candidates for adjuvant therapy studies.

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

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Radiation Oncology + Radiotherapy
    • Presentations: 1
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      P3.08-007 - Stereotactic Ablative Radiotherapy (SABR) of Centrally Located Early Stage Lung Cancer Accrued to RTOG 0813: Novel Scoring System to Compare Plan Quality of Volumetric Modulated Arc Therapy (VMAT) versus Robotic Radiosurgery (ID 1068)

      09:30 - 16:30  |  Author(s): V.J. Nair

      • Abstract

      Background
      Central lung tumours pose a challenge for stereotactic ablative radiotherapy (SABR) due to proximity to vital organs and risk of potentially fatal toxicity. RTOG 0813 is an attempt to determine a safe dose for these tumours in an era where many institutions have multiple technologies that can deliver lung SABR. The purpose of this study is to use a novel scoring system to compare two different SABR platforms, robotic radiosurgery (RRS) and linac-based volumetric modulated arc therapy (VMAT), in a cohort of patients actually treated on 0813. The comparison is limited to target coverage and organ-at-risk (OAR) sparing capability for this technically challenging group of patients.

      Methods
      All 5 patients from our institution accrued to RTOG 0813 were selected for this study. Eight planners (4 VMAT, 4 RRS) with combined experience of >500 lung SABR cases re-planned each case for 60 Gy in 5 fractions. Patient setup, contouring details, and planning constraints were as per 0813. Monte Carlo planning was performed on Monaco v3.20 (Elekta Inc., MI, USA) for VMAT and Multiplan v4.5.0 (Accuray Inc., Sunnyvale, USA) for RRS on CyberKnife. An objective scoring system was designed that included each dose-volume 0813 protocol criterion. For each target requirement or OAR constraint a “structure score” was assigned whereby [Actual Plan parameter /Expected 0813 parameter] X priority factor = structure score. Priority factors (high 0.9, intermediate 0.6, and low 0.3) were assigned by 3 experienced lung SABR radiation oncologists for each of the 5 patients given that different OARs were of greater concern depending on exact target location. A ‘final plan score’ was the sum of all structure scores, with a lower overall score indicating a plan that best achieved target coverage and OAR avoidance in keeping with radiation oncologist priority. To reduce inter-planner bias more than one plan was created for each of the 5 patients using both modalities and only the best plans were selected for comparison.

      Results
      A total of 15 VMAT and 10 RRS plans were submitted for analysis, each satisfying the minimum 0813 protocol requirements. Using the scoring system, a final plan score was obtained for all 25 plans with a median VMAT score of 8.02 (range 5.52 to 10.09) and RRS score of 7.1 (range 4.98 to 12.41). The lowest scoring VMAT plan was then compared with the lowest scoring RRS plan for each patient. Analysis of target coverage parameters showed that both modalities had similar scores, indicating an equivalent ability to conformally cover the target. RRS plans had lower OAR scores (mean reduction of 1.3) compared to VMAT plans. Overall the plan scores for each patient (RRS: VMAT) were: Patient 1 (6.74:9.2), Patient 2 (6.69:7.32), Patient 3 (4.98:5.94), Patient 4 (7.69:8.92), Patient 5 (5.78:7.36).

      Conclusion
      When using a scoring system based on RTOG 0813 planning criteria to compare patient plans from two different lung SABR delivery systems, 5 of 5 patients planned using a robotic radiosurgery system had more favourable overall scores compared to VMAT linac delivery for centrally located tumours.