Pathological complete response in a patient with locally advanced pancreatic adenocarcinoma treated with neoadjuvant gemcitabine and S-1: a case report and literature review.

Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide. Radical resection is currently the only potential curative treatment. However, over 80% of patients present with unresectable tumor at the time of diagnosis. It is recommended that patients with unresectable pancreatic cancers be offered neoadjuvant treatment. A combination of gemcitabine and S-1 (GS-1) has been reported to be an effective regimen for unresectable pancreatic cancers, however, there have been no reports of pathological complete response up until now. Case Description: Herein, we present a 67-year-old male who presented with a 4-month history of upper abdominal and back pain, as well as unintentional weight loss. Abdominal computed tomography (CT) confirmed a hypovascular mass in the pancreas neck consistent with unresectable pancreatic cancer. Positron emission tomography (PET)/CT also revealed a high fludeoxyglucose (FDG)-avid lesion in the pancreas neck without evidence of distant metastasis. Pancreatic adenocarcinoma was confirmed with ultrasound-guided fine-needle aspiration cytology. The patient was recommended to undergo treatment with gemcitabine and S-1. After 5 cycles of neoadjuvant chemotherapy, CT and PET/CT both revealed the disappearance of the lesion and a pancreaticoduodenectomy was offered as a potentially curative treatment. Histological assessment revealed no evidence of residual adenocarcinoma [ypT0N0 (0/38)]. The tumor marker cancer antigen (CA)125 increased one month after the surgery, resulting in two additional cycles of GS-1. This patient remained disease-free for 21 months after surgery. Conclusions: This report is the first to present a case of a pathological complete response in a patient with locally advanced pancreatic cancer following GS-1 treatment, suggesting radical resection after GS-1 chemotherapy might be a potential curative treatment strategy for unresectable PDAC. 2022 Gland Surgery. All rights reserved.