Pretreatment lab values to predict overall survival in patients with primary unresectable pancreatic adenocarcinoma treated with SBRT.

Abstract

433 Background: This study investigates which pre-treatment hematologic and tumor marker values can predict for overall survival (OS) in patients with unresectable pancreatic adenocarcinoma treated with stereotactic body radiotherapy (SBRT) using data from the past 11 years from a single institution. Methods: Clinical data from 196 patients with primary unresectable pancreatic adenocarcinoma treated with SBRT at our institution from 2002 to 2013 was collected. Of these, 161 (82.1%) had locally advanced disease, 12 (6.1%) had borderline resectable disease, 21 (10.7%) were medically inoperable, and 2 (1.0%) had resectable disease but refused surgery. Prior to the start of treatment, lab values were collected for 191 of these patients including: hemoglobin, platelets, albumin, red blood cell (RBC) count, white blood cell (WBC) count, absolute lymphocyte count, absolute neutrophil count, and neutrophil to lymphocyte ratio (NLR). Additionally, tumor markers CA 19-9 and CEA were collected. Background clinical and demographic data was also available for the entire cohort. Results: The median follow-up for the entire cohort following SBRT was 7.7 months. Median OS from the start of treatment was 7.88 months (IQR 4.96-12.72). Prior radiation therapy (p = 0.0462), lower RBC (p = 0.0307), higher pre-treatment CEA (p = 0.0166), and higher NL ratio (p < 0.0001) correlated with worse OS on univariate analysis. WBC, platelet counts, and CA 19-9 did not predict for OS on univariate analysis. On multivariate analysis, higher NL ratio (p = 0.0455) and higher CEA (p = 0.0148) were both correlated with decreased OS, while RBC and prior radiation therapy had no association. Conclusions: Review of pre-treatment hematologic and tumor marker values serves as a valuable predictor of overall survival in patients with unresectable pancreatic adenocarcinoma treated with SBRT. Higher pre-treatment NL ratio and CEA values are associated with poorer OS, which may help to stratify patients into different risk categories.