Patterns of peritoneal dissemination and response to systemic chemotherapy in common and rare peritoneal tumors treated by cytoreductive surgery: Study protocol of a prospective, multi-center, observational study

Introduction Despite optimal patient selection and surgical effort, recurrence is seen in over 70% of patients undergoing cytoreductive surgery(CRS) for peritoneal metastases (PM). Apart from the peritoneal cancer index(PCI), completeness of cytoreduction and tumor grade, there are other factors like disease distribution in the peritoneal cavity, pathological response to systemic chemotherapy(SC), lymph node metastases and morphology of PM which may have prognostic value. One reason for the underutilization of these factors is that they are known only after surgery. Identifying clinical predictors, specifically radiological predictors, could lead to better utilization of these factors in clinical decision making and the extent of peritoneal resection performed for different tumors. This study aims to study these factors, their impact on survival and identify clinical and radiological predictors. Methods and analysis There is no therapeutic intervention in the study. All patients with biopsy proven PM from colorectal, appendiceal, gastric and ovarian cancer and peritoneal mesothelioma undergoing CRS will be included. The demographic, clinical, radiological, surgical and pathological details will be collected according to a pre-specified format that includes details regarding distribution of disease, morphology of PM, regional node involvement and pathological response to SC. In addition to the absolute value of PCI, the structures bearing the largest tumor nodules and a description of the morphology in each region will be recorded. A correlation between the surgical, radiological and pathological findings will be performed and the impact of these potential prognostic factors on progression-free and overall survival determined. The practices pertaining to radiological and pathological reporting at different centers will be studied. Ethics and dissemination The study protocol has been approved by the Zydus Hospital ethics committee (27 th July, 2020) and Lyon-sud ethics committee (A15-128). It is registered with the clinical trials registry of India (CTRI/2020/09/027709). The results will be published in peer-reviewed scientific journals. Strength and limitations A prospective correlation between the radiological, surgical and pathological findings in patients undergoing CRS will be performed which has not been done before. Being prospective in nature it will also enable us to evaluate the impact of the current treatment practices on the clinical end-points There is fixed protocol for radiological and pathological evaluation for which there are no specific guidelines The data collection format will capture all the relevant data but this may affect compliance. Despite the large sample size planned for each primary site, the heterogeneity of treatment protocols may be a limiting factor while evaluating the impact on survival.