HPB P12 Do Chemotherapy Factors or Treatment Intervals Influence Pathological Tumour Response during Neoadjuvant Chemotherapy for Pancreatic Ductal Adenocarcinoma? A Bi-Institutional Study

Abstract

Abstract Background Pathological response of pancreatic ductal adenocarcinoma (PDAC) to neoadjuvant chemotherapy (NAT) can be assessed using grading systems such as the College of American Pathologists (CAP) system, with favourable regression being associated with improved oncological outcomes. The aim of the study was to investigate factors associated with favourable tumour regression in patients undergoing pancreatoduodenectomy (PD) for PDAC. Methods Patients who received NAT before undergoing PDAC resection at two institutions in the United Kingdom between 2013 and 2021 were reviewed. Interactions between chemotherapy regimens, tumour staging, carbohydrate antigen 19-9 (Ca19-9) levels, perioperative factors and tumour regression grading (TRG) were explored. Results 54 patients were identified who were suitable for inclusion. 12 (22%) patients had a favourable response to NAT according to the CAP grading system. A significantly greater reduction in Ca19-9 observed in the favourable TRG group [mean -2359 U/mL] compared to the unfavourable TRG group [mean -569 U/mL (p<0.001). The type of chemotherapy agent received, the number of cycles or whether the patient had a dose reduction during their NAT course did not differ significantly between the groups. The time from diagnosis to chemotherapy and time from end of chemotherapy to surgery were also similar between the groups. Conclusions In this bi-institutional retrospective study, neither chemotherapy factors nor treatment intervals were not found to be significantly related to pathological tumour response to NAT in PDAC patients undergoing resection. Given that a favourable pathological response has been related to improved oncological outcomes, future research should concentrate on further mechanisms that may influence the response of PDAC tumours to NAT, such as gene expression and the tumour microbiome. Given that NAT is also a relatively new approach, further multicentre collaboration should be encouraged to increase numbers of patients for study.