Analysis of Prognostic Factors in Pancreatic Metastases: A Multicenter Retrospective Analysis

OBJECTIVES Pancreatic metastases (PMs) account for 1% to 2% of pancreatic tumors, and their prognostic significance is poorly defined. We evaluated the incidence and clinical characteristics of primary tumors and defined prognostic factors. METHODS This retrospective study of 39 Japanese tertiary referral hospitals (January 2005 to August 2015) analyzed patient and tumor characteristics and survival time. Kaplan-Meier analysis and Cox proportional hazards models were applied to evaluate overall survival and prognostic factors, respectively. RESULTS We enrolled 159 patients with a pathologic diagnosis of PM. The most common primary tumor was renal cell carcinoma (38.4%), followed by lung cancer (24.5%), colorectal cancer (11.3%), and sarcoma (6.3%). Eight patients were lost during follow-up, and 151 patients were included for statistical analysis. Median overall survival was 43.0 months, and the 5-year survival rate was 42.6%. Multivariate analysis identified 3 independent prognostic factors: extrapancreatic metastasis (hazard ratio, 2.13; 95% confidence interval, 1.11-4.07; P = 0.02), tumor-related symptoms at diagnosis (hazard ratio, 5.39; 95% confidence interval, 2.92-9.91; P < 0.001), and pathologic diagnosis of primary tumors (P < 0.001). CONCLUSIONS Treatment strategies and prognoses for PMs completely differ according to the primary tumor type. A definitive pathologic diagnosis of PMs is essential for selecting the appropriate treatment.