Authors’ Reply to Wu et al. “Comment on: Repeat Cytoreductive Surgery and Intraperitoneal Chemotherapy for Colorectal Cancer Peritoneal Recurrences is Safe and Efficacious”

Abstract

We would like to thank Wu et al. for their interest in our work and their insightful comments, and we also thank the editors of Annals of Surgical Oncology for an opportunity to reply to their comments. First, we would like to address the issue of completeness of cytoreduction, presence of additional non-peritoneal metastasis, and additional treatment strategies on oncological outcomes. We examined our cohorts of initial and repeat procedures and they were indeed similar in regard to these factors; complete cytoreduction (CC0) was 91.6% and 100% in our initial and repeat cohorts, respectively. In regard to extraperitoneal disease, 21.8% and 16.7% of patients had liver metastasis along with their peritoneal disease in the initial and repeat cohorts, respectively. In terms of preoperative chemotherapy, the groups were again similar, with 91.3% and 100% of patients receiving preoperative chemotherapy in the initial and repeat groups, respectively. Unfortunately, we do not have sufficient data to compare the number of cycles and types of preoperative chemotherapy received. Thus, while we agree that these factors are important in assessing the outcomes of patients after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) for colorectal peritoneal metastasis (CRPM), our groups were sufficiently similar in these regards and we do not believe that this affected our results in a significant manner. In terms of patients with high Peritoneal Cancer Index (PCI), being a peritoneal malignancy center of excellence and quaternary referral center, we are often presented with complex patients with significant disease burden and high PCI. After multidisciplinary tumor board evaluation, some patients with higher PCI (12–20) are offered exploration and potentially CRS/HIPEC. As noted in most large CRS/ HIPEC series, surgical PCI often differs significantly from radiological PCI, and, in appropriate patients where suitable CC0 can still be obtained, we will proceed with treatment and results are favorable. Furthermore, as has been previously described, we often find that clinical operative PCI differs significantly from pathological PCI and those patients may benefit despite high operative PCI. Yet, it is clear from our multivariable analysis that indeed high PCI has a negative prognostic effect on overall survival and should be carefully considered in selection. We believe that the fact that these patients were included, and the data still suggest a positive effect of CRS/HIPEC, only further strengthens our conclusions. Wu et al. expressed interest in the overall survival (OS) of both the isolated and repeat CRS/HIPEC groups, and expressed a desire for more clarification about patient selection. The reason OS was not included in the manuscript is that comparing the OS of a group of patients with initial disease with a very highly selected group of patients, all of whom had already recurred, is an unfair comparison given that the latter group clearly have worse biology. In all isolated CRS/HIPEC, the median OS was 62 months, while in the repeat CRS/HIPEC group, the median OS was 38 months (p = 0.049). A more accurate comparison, which we included, is between the OS in all patients who had a peritoneal-only recurrence and compare those who did versus did not undergo repeat CRS/HIPEC. In this Society of Surgical Oncology 2021