Systemic Chemotherapy in Colorectal Peritoneal Metastases Treated with Cytoreductive Surgery: Systematic Review and Meta-Analysis

Simple Summary There is little evidence about the optimal timing of systemic chemotherapy (SC) in patients treated with cytoreductive surgery (CRS) and HIPEC for colorectal peritoneal metastases (CRC-PM). Due to the lack of evidence in this field, a systematic literature search and a meta-analysis of relevant studies were performed. Twenty-one studies were included in the systematic review and fifteen in the quantitative analysis (4523 patients). Postoperative SC was associated with increased overall survival compared to no SC or a preoperative SC regimen, whereas SC (pre or post) and pre-SC compared to surgery alone were not. Similar results were found for disease-free survival. Preoperative SC was not associated with an increased risk of severe surgical complications.Abstract Background. For patients with colorectal cancer (CRC) peritoneal metastases (PM) who are eligible for cytoreductive surgery (CRS), the indication and timing of systemic chemotherapy (SC) are still under debate. This study aims to analyze the role of pre, post or perioperative SC on the survival and surgical complications of patients treated with CRS-HIPEC. Methods. After a systematic search in MEDLINE, Cochrane Database of Systematic Reviews, Scopus, Web of Science and Embase, a meta-analysis was performed to compare postoperative complications, disease-free survival (DFS) and overall survival (OS) according to SC administration and timing. PROSPERO: CRD42023478977. Results. Of 1203 studies screened, 15 were included in the meta-analysis (4523 patients). Post-operative SC was associated with increased overall survival (post-SC vs. no post-SC: HR 0.81, p = 0.00001, I2 = 0%; pre-SC vs. post-SC: HR 0.65, p = 0.01, I2 = 28%), whereas SC (pre or post) or pre-SC compared to surgery alone was not (SC vs. no SC: p = 0.29, I2 = 80%; pre-SC vs. no pre-SC: p = 0.59, I2 = 58%). Similar results were seen for DFS. SC was not associated with an increased complication rate (p = 0.47, I2 = 64%). Conclusions. Systemic chemotherapy administration in patients undergoing radical surgery for colorectal peritoneal metastases is associated with increased survival only in the adjuvant/post-operative setting. Considering the limitations of the included studies, further trials are needed to answer this unresolved question.