The Prognostic Role of FDG PET/CT in Locally Advanced Gastric Cancer Receiving Neoadjuvant Chemotherapy

Abstract

Introduction: Neoadjuvant chemotherapy (NAC) is the one of treatment option for the patients with locally advanced gastric cancer (LAGC). Recent studies showed metabolic parameters of F-18 FDG PET/CT had correlation with prognosis in gastric cancer patients. This study aimed to evaluate the prognostic significance of metabolic parameters using FDG PET/CT in LAGC patients receiving NAC. Methods: This is a retrospective study with the patients diagnosed with locally advanced gastric cancer from January 2006 to January 2015. 39 consecutive patients (mean age 59 ± 10, range 40 ˜ 79, male 27, female 12) underwent baseline PET/CT prior to NAC, and restaging PET/CT for response evaluation after NAC. We measured SUVmax of primary tumor on baseline PET/CT (SUV1), and SUVmax for primary tumor on restaging PET/CT (SUV2), and calculated percentage change (SUVΔ%). SUV1, SUV2, SUVΔ%, age, sex, staging, histologic grade, peritoneal washing cytology were analyzed for association with overall survival (OS). Results: The mean SUV1, SUV2 and SUVΔ% were 11.1 ± 5.8 (range 2.9˜28.5), 6.5 ± 4.0 (1.8˜17.2) and 42.0 ± 33.2 (-24.0˜85.0), respectively. SUV1, SUV2 and SUVΔ% were dichotomized by median value (11.0, 6.0 and 42.0, respectively). Higher SUV2 (≥6) showed inferior OS compared to lower SUV2 (p=0.044, hazard ratio (HR)=5.21). Female gender (p=0.007, HR=3.31) and positive washing cytology (p=0.032, HR=3.17) were significantly associated with inferior OS. Conclusion: NAC in patients with LAGC can increase R0 resection rate and provide survival benefit. To find out prognostic factor is important for guiding treatment plan. Aggressive treatment is needed to the patients with poor prognostic factor. Among the multiple metabolic parameters, high SUVmax of primary tumor after NAC indicates inferior OS in LAGC patients. Further study with large sample size and single regimen of NAC is needed.