Preoperative volume-based PET parameter, MTV_2.5, as a potential surrogate marker for tumor biology and recurrence in resected pancreatic cancer

This study aims to evaluate the role of volume-based positron emission tomography parameters as potential surrogate markers for tumor recurrence in resected pancreatic cancer. Between January 2008 and October 2012, medical records of patients who underwent surgical resection for pancreatic ductal adenocarcinoma and completed 18¹⁸-fluorodeoxyglucose positron emission tomography/CT as a part of preoperative staging work-up were retrospectively reviewed. Not only clinicopathologic variables but also positron emission tomography parameters such as SUVmax, MTV_2.5 (metabolic tumor volume), and TLG (total lesion glycolysis) were obtained. Twenty-six patientswerewomen and 31were men with a mean age of 62.9-9.1 years. All patients were preoperatively determined to resectable pancreatic cancer except 1 case with borderline resectability. R0 resection was achieved in all patients and 45 patients (78.9%) received postoperative adjuvant chemotherapy with or without radiation therapy. Median overall disease-free survival was 12.8 months with a median overall disease-specific survival of 25.1 months. SUVmax did not correlate with radiologic tumor size (P=0.501); however,MTV_2.5 (P=0.001) and TLG(P=0.009)were significantly associatedwith radiologic tumor size. In addition, MTV_2.5 (P<0.001) and TLG (P<0.001) were significantly correlated with a tumor differentiation. There were no significant differences in TLG and SUVmax according to lymph node ratio; only MTV_2.5 was related to lymph node ratiowithmarginal significance (P=0.055). In multivariate analysis, lymph node ratio (Exp [b]=2.425, P=0.025) and MTV_2.5 (Exp[b]=2.273, P=0.034) were identified as independent predictors of tumor recurrence followingmargin-negative resection. Even after tumor size-matched analysis, MTV_2.5 was still identified as significant prognostic factor in resected pancreatic cancer (P<0.05). However, preoperative neoadjuvant treatment attenuated adverse oncologic impact of high preoperative MTV_2.5 (P=0.210). Preoperatively determined volume-based PET parameter, MTV_2.5, can potentially be used as a surrogate marker to estimate tumor biology and tumor recurrence. Individual treatment strategies for pancreatic cancer can be suggested based on patients' preoperative MTV_2.5.