Scoring of tumour response after neoadjuvant therapy in resected pancreatic cancer: systematic review

BACKGROUND: Preoperative chemo(radio)therapy is used increasingly in pancreatic cancer. Histological evaluation of the tumour response provides information on the efficacy of preoperative treatment and is used to determine prognosis and guide decisions on adjuvant treatment. This systematic review aimed to provide an overview of the current evidence on tumour response scoring systems in pancreatic cancer.METHODS: Studies reporting on the assessment of resected pancreatic ductal adenocarcinoma following neoadjuvant chemo(radio)therapy were searched using PubMed and EMBASE. All original studies reporting on histological tumour response in relation to clinical outcome (survival, recurrence-free survival) or interobserver agreement were eligible for inclusion. This systematic review followed the PRISMA guidelines.RESULTS: The literature search yielded 1453 studies of which 25 met the eligibility criteria, revealing 13 unique scoring systems. The most frequently investigated tumour response scoring systems were the College of American Pathologists system, Evans scoring system, and MD Anderson Cancer Center system, investigated 11, 9 and 5 times respectively. Although six studies reported a survival difference between the different grades of these three systems, the reported outcomes were often inconsistent. In addition, 12 of the 25 studies did not report on crucial aspects of pathological examination, such as the method of dissection, sampling approach, and amount of sampling.CONCLUSION: Numerous scoring systems for the evaluation of tumour response after preoperative chemo(radio)therapy in pancreatic cancer exist, but comparative studies are lacking. More comparative data are needed on the interobserver variability and prognostic significance of the various scoring systems before best practice can be established.