Neoadjuvant and Adjuvant Chemotherapy for Pancreatic Adenocarcinoma: Literature Review and Our Experience of NAC-GS.

In addition to established evidence of the efficacy of adjuvant chemotherapy (AC) for pancreatic ductal adenocarcinoma (PDAC), evidence of the effects of neoadjuvant treatments (NATs), including chemotherapy and chemoradiotherapy, has also been accumulating. Recent results from prospective studies and meta-analyses suggest that NATs may be beneficial not only for borderline resectable PDAC, but also for resectable PDAC, by increasing the likelihood of successful R0 resection, decreasing the likelihood of the development of lymph node metastasis, and improving recurrence-free and overall survival. In addition, response to NAT may be informative for predicting the clinical course after preoperative NAT followed by surgery; in this way, the postoperative treatment strategy can be revised based on the effect of NAT and the post-neoadjuvant therapy/surgery histopathological findings. On the other hand, the response to NAT and AC is also influenced by the tumor biology and the patient's immune/nutritional status; therefore, planning of the treatment strategy and meticulous management of NAT, surgery, and AC is required on a patient-by-patient basis. Our experience of using gemcitabine plus S-1 showed that this NAT regimen achieved tumor shrinkage and decreased the levels of tumor markers but failed to provide a survival benefit. Our results also suggested that response/adverse events to NAT may be predictive of the efficacy of AC, as well as survival outcomes.