This study investigated the oncologic impact of loss of SMAD4 expression in resected left-sided pancreatic cancer and its correlation with tumor metabolism.From 2005 to 2011, the medical records of patients who underwent radical distal pancreatectomy for resectable pancreatic cancer were retrospectively reviewed. Formalin-fixed, paraffin embedded tissue from 32 patients was investigated. Clinicopathological characteristics, immunostaining of SMAD4, and positron emission tomography-based parameters were analyzed in relation to oncologic outcomes.Thirteen patients were women and 19 were men, with a mean age of 63 ± 9.4 years. Mean resected tumor size was 3.3 ± 1.5 cm. Ten patients (31.3%) showed loss of SMAD4 expression. No significant clinicopathological differences were noted according to SMAD4 expression (P > 0.05); however, patients with loss of SMAD4 showed significantly poorer disease-free survival (mean 57.4 months vs mean 17.6 months, P = 0.006). As a cut-off value, a SUVmax of 4.5 was found to be predictive of loss of SMAD4 with a sensitivity of 75% and a specificity of 84.6%. In logistic regression analysis, SUVmax>4.5 was found to infer a 16-fold higher risk for loss of SMAD4 in resected left-sided pancreatic cancers (Exp[β] = 16.5, P = 0.012, 95% confidence interval: 1.832-148.606).Loss of SMAD4 is associated with poor oncologic outcomes. SUVmax can predict loss of SMAD4 in resected left-sided pancreatic cancer. SUVmax may be a clinical biomarker for detecting loss of SMAD4 expression and predicting early systemic metastasis.