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Y. Pu



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    O29 - Cancer Control & Epidemiology IV (ID 132)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Prevention & Epidemiology
    • Presentations: 1
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      O29.06 - Prognostic Value of FDG-PET/CT Volumetric Prognostic Staging System in Non-small Cell Lung Caner (ID 2278)

      10:30 - 12:00  |  Author(s): Y. Pu

      • Abstract
      • Presentation
      • Slides

      Background
      Whole-body metabolic tumor volume (MTV~WB~) is a prognostic index independent of TNM staging, age, gender, performance status and treatment in non-small cell lung cancer (NSCLC). The current TNM staging system is also a prognostic index. However, it lacks advanced quantitative volumetric measurement in the 7[th] edition NSCLC TNM staging system. Integrating quantitative MTV~WB~ measurement into the current NSCLC staging system may make the staging system more quantitative and probably more prognostic. This study’s aim was to determine the utility of a FDG-PET volumetric prognostic (PVP) staging system based on univariate Cox regression models as a new prognostic index in NSCLC.

      Methods
      328 consecutive patients (156 males,172 females) with histologically proven NSCLC and median age of 68.3 years were identified for this retrospective analysis. The PET metabolic tumor volume in the whole body (MTV~WB~) was measured using a semi-automated 3D contouring program on baseline FDG PET/CT scans. The prognostic power for survival status of the PVP staging system was evaluated using the Kaplan–Meier method, Cox regression models, and compared with those of TNM staging system and ln(MTV~WB~) using C-statistic index (Gönen and Heller’s K concordance statistic).

      Results
      There were 46 cases with stage IA, 43 stage IB, 19 stage IIA, 18 stage IIB, 52 stage IIIA, 39 stage IIIB and 111 stage IV NSCLC. At the end of this investigation, 249 patients had died (88.4%). Median follow-up of 79 lost follow-up and known surviving patients was 58 months. On univariate survival analysis the HR of ln(MTV~WB~) was 1.56, and the HRs of TNM stages 2.25, 1.96, 2.89, 4.24, 4.93 and 7.63 for TNM stages IB, IIA, IIB, IIIA, IIIB and IV in reference to stage IA, respectively. These HRs were used for computing the PVP stage of each patient using following equation; PVP stage = [Hazard ratio of ln(MTV~WB~) × ln(MTV~WB~)] × [Hazard ratios of TNM stage]. There was a statistically significant association of better overall survival with lower PVP stage on both univariate [HR of 1.033 (95%CI =1.027 to1.039)] and multivariate [HR of 1.03 (95%CI =1.02 to1.04)] survival analyses. The range of the PVP stage were 0.06 to 87.57. For comparison with 7[th] edition of TNM stage and ln(MTV~WB~), the PVP stage and ln(MTV~WB~) were divided into 7 groups with similar numbers of patients. The C-statistic value of PVP staging system (mean±SE = 0.70±0.014) was statistically significantly higher than those of TNM stage (0.67 ±0.015, p=0.002) and ln(MTV~WB~) (0.67±0.015, p=0.02) on univariate survival analysis. In multivariate Cox regression models adjusted by patient’s age, gender, treatment types, tumor histology and tumor SUV~max~, the C-statistic value of PVP staging system (mean±SE=0.73±0.013) was also statistically significantly higher than that of TNM stage (0.71 ±0.015, p=0.036).

      Conclusion
      The PVP staging system from FDG-PET/CT has better prognostic ability and may prove to be a useful prognostic index in NSCLC. It can be treated as a complement to the TNM staging system.

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    P1.19 - Poster Session 1 - Imaging (ID 179)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Imaging, Staging & Screening
    • Presentations: 1
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      P1.19-010 - Prognostic Value of FDG-PET-based Metabolic Tumor Volume<br /> in Conjunction with Mathematical Classifiers<br /> in Non-small Cell Lung CancerPatients (ID 2983)

      09:30 - 16:30  |  Author(s): Y. Pu

      • Abstract

      Background
      The TNM staging system for prognostication in non-small cell lung cancer (NSCLC) is less than satisfactorily accurate. Previous research suggests that FDG-PET-based metabolic tumor volume (MTV) may be an independent prognostic marker in NSCLC when used in Cox-regression models. This study was to determine the potential prognostic utility of FDG-PET-based MTV used in mathematical classifiers for prognostication of NSCLC.

      Methods
      A consecutive cohort of 328 NSCLC patients (156 males, 172 females) with histologic confirmation and FDG-PET scans was identified for retrospective analysis. MTV measurements were made on baseline 18F-FDG PET/CT scans of the primary tumor (MTV~T~), metastatic lymph nodes (MTV~N~), and metastatic tumors (MTV~M~). Whole-body MTV (MTV~WB~) was defined as the sum of MTVs of primary tumor, metastatic lymph nodes, and metastatic tumors (MTV~WB~ = MTV~T~ + MTV~N~ + MTV~M~). A semi-automated 3D contouring program was used for obtaining the MTVs. Patient survival was determined from cancer registry data, and known survival length of living and lost-to-follow-up (i.e., censored) patients was recorded. Patient survival was determined at one year (189 survived, 129 did not) and two years (127 survived, 186 did not) after baseline FDG-PET scan, and survival status was known for most censored patients except for ten at one year and 15 at two years. Linear discriminant analysis classifiers were constructed on data of patient age, gender, histology, TNM stage, and MTVs. Cross-validation was done as follows: to predict a patient's survival status, a classifier was trained on data of all other patients of known survival status and not on the patient in question. Areas under receiver operating characteristic (ROC) curve (AUC), analogous to C concordance statistics, were compared statistically.

      Results
      The median patient age was 68.3 years and patient distribution by stage was 46 stage IA, 43 stage IB, 19 stage IIA, 18 stage IIB, 52 stage IIIA, 39 stage IIIB, and 111 stage IV. Median follow-up of living and lost-to-follow-up patients was 58 months and death confirmation was known in 249 (88.4%) patients. For one-year survival, the AUC (± standard error) value of the classifier based on age, gender, histology, and stage was 0.77±0.026 and that of the classifier based on age, gender, histology, stage, and MTVs was 0.82±0.023 (p < 0.01). For two-year survival, the corresponding AUC values were 0.75±0.028 and 0.79±0.026, respectively (p < 0.02). The AUC values were similar for classifiers based on age, gender, histology and MTVs and for classifiers based on age, gender, histology, and stage (p > 0.5). These results were consistent with previous results of statistically significantly better prognostic ability of multivariate Cox-regression models of MTV~WB~ compared with models not including MTV~WB~, after adjusting for age, gender, histology, treatment options, and whole-body tumor SUV~max~.

      Conclusion
      FDG-PET-based metabolic tumor volume can potentially increase prognostic accuracy for NSCLC patients beyond that of the TNM staging system at one and two years, and mathematical linear classifiers can potentially be used as an alternative to Cox-regression models for estimating survival probability.