Prognostic value of the PET/CT volumetric prognostic (PVP) index/stage and survival advantage of surgical patients over non-surgical patients in NSCLC (2016)

187 Objectives We have previously demonstrated the PET/CT volumetric prognostic (PVP) index is a more accurate metric of patient survival than the TNM staging of NSCLC patients, which may lead to better treatment decision-making and improvement of patient prognosis. This study was to further assess the prognostic value of the PVP index after controlling for age, gender, and tumor histology in a large patient population. We also evaluated whether overall survival is better in surgically treated patients than those treated non-surgically, across different values of the PVP index. Methods Quantitative metabolic tumor volume (MTVWB) was determined using PET/CT and combined with clinical TNM stage to determine the PVP index retrospectively in 882 biopsy proven NSCLC patients. The PVP index was grouped into 4 stages based on quartiles (PVP stages 1 to 4) and Kaplan-Meier curves of overall survival and log-rank tests within each PVP stage were generated. Cox regression analyses were also performed. The patients were selected and divided according to surgical or non-surgical treatment. MTVWB was measured with the PETedge tool of the MIM software with manual adjustment when needed. The PVP index was then generated based on the MTVWB and TNM stage using the following formula: 0.360[asterisk]ln(MTVWB) + 0.424[asterisk]I(TNM=III) + 0.890[asterisk]I(TNM = IV), with the indicator function I(·) yielding a value of 1 when its argument is true and 0 otherwise. Results The median age was 68 years (range 17-92), and 54% were women. Median follow-up among survivors was 38 months (25th to 75th percentile 24 - 66 months). The most common histology was adenocarcinoma (47%), followed by squamous (27%) and not otherwise specified (17%). The majority of patients had advanced disease (Stage I/II/III/IV: 28%/11%/ 30%/31%). 34% of patients received surgical treatment +/- additional therapies. Of the remaining patients, 42% received chemotherapy and radiation therapy, 26% received chemotherapy, 17% received radiation therapy, and 15% received no cancer specific treatment. The median MTVWB was 41 ml (25%’ile = 9, 75%’ile = 149 ml). A lower PVP index was significantly associated with better overall survival (univariate Cox regression p Conclusions Selection of optimal treatment options in NSCLC based on the TNM staging system can be improved since it provides no dimensional measurement of nodal and distant metastases, and there are substantial variations in patient survival even within the same TNM stage following standard treatment. This study demonstrated the prognostic value of the PVP index independent of age, gender and tumor histology and surgical status. The PVP index also demonstrated better overall survival of surgically treated patients than those treated without surgery across different PVP stages, which may be due to benefit of surgery and/or potential difference of other prognostic factors (such as performance status) between surgical and non-surgically treated patients not adjusted in the multivariate cox regression model.
Research Support: This work was supported in part by a grant (R21 CA181885) from the National Cancer Institute of the National Institutes of Health.