Lymph node yield during surgery after neoadjuvant therapy compared to surgery without neoadjuvant therapy in patients with esophageal, gastric, pancreatic, or rectal carcinoma: systematic review and meta-analysis (Preprint)

BACKGROUND The lymph node yield is an important surrogate parameter for assessing the oncological radicality of the resection of gastrointestinal carcinomas and a prognostic factor in these diseases. It remains unclear if and to what extent neoadjuvant chemotherapy, radiotherapy or chemoradiotherapy, which have become established treatments for carcinoma of the esophagus, stomach, and rectum and are increasingly used in pancreatic carcinoma, affect the lymph node yield. OBJECTIVE This systematic review with meta-analysis is conducted with the aim of summarizing the available evidence regarding the oncological surrogate marker lymph node yield in patients with gastrointestinal carcinomas undergoing surgery after neoadjuvant treatment compared to those operated without neoadjuvant therapy. METHODS Studies comparing oncological resection of esophageal, stomach, pancreatic and rectal carcinoma with and without prior neoadjuvant therapy are eligible for inclusion regardless of study design. Publications will be identified with a defined search strategy in the electronic databases PubMed and Cochrane Library. The primary endpoint of the analysis is the number of lymph nodes identified in the resected specimen. Secondary endpoints include number of harvested metastatic lymph nodes, operation time, postoperative complications, pTNM staging, and overall and recurrence-free survival time. Using suitable statistical methods, the endpoints between patients with and without neoadjuvant therapy as well as in defined subgroups (neoadjuvant chemotherapy, neoadjuvant radiotherapy, neoadjuvant chemoradiotherapy, and esophageal, gastric, pancreatic, and rectal cancer) will be compared. RESULTS As of October 2021, we started with the data collection. CONCLUSIONS This systematic review with meta-analysis is conducted with the aim of summarizing the available evidence regarding the oncological surrogate marker lymph node yield in patients with gastrointestinal carcinomas undergoing surgery after neoadjuvant treatment compared to those operated without neoadjuvant therapy. CLINICALTRIAL This systematic review is registered at PROSPERO, ID: 218459.