Efficacy of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in cases of peritoneal carcinomatosis secondary to gastrointestinal system tumors

Background Peritoneal carcinomatosis is a condition characterized by the presence of tumor implants of various sizes in the visceral and parietal peritoneum, and is a condition that occurs in the advanced stage of gastrointestinal system malignancies or as one of the forms of recurrence after treatment. The effect of systemic chemotherapy in this situation is low, and it is predicted that locoregional treatments will be more effective, and the effectiveness of cytoreductive surgery (SRC) and hyperthermic intraperitoneal chemotherapy (HIPEC) method, which has been developed in studies conducted in various centers since the 1980s, has been demonstrated in many case series. In this study, it was aimed to retrospectively examine the cases of SRC and HIPEC performed in our unit, to evaluate the progression-free and overall survival times, and to examine the prognostic factors. Material and methods In our study, 89 patients who underwent CRS + HIPEC with the diagnosis of peritoneal carcinomatosis between January 2011 and September 2022 in the Istanbul Medical Faculty General Surgery Clinic were retrospectively analyzed. Patients were evaluated based on age, gender, tumor location, drug used for intraperitoneal chemotherapy, cytoreduction score (CC), systemic chemotherapy history, peritoneal cancer index (PCI), lymph node metastasis, early and late complications, progression-free survival (PFS), and overall survival (OS). Complications were grouped according to the Clavien-Dindo classification. Grade 3 and above were considered as major complications. Deaths in the first 30 days after surgery were considered as early postoperative mortality. SPSS version 25.0 was used for statistical analysis. Survival calculations were made using the Kaplan-Meier analysis method. The effects of various prognostic factors related to tumor and patient characteristics on progression-free and overall survival were investigated by log-rank test. The effects of multiple prognostic factors on progression-free and overall survival were investigated using the multivariate Cox regression test. Categorical comparisons between groups were calculated by Chi-square tests. The results were evaluated at the 95% confidence interval and the significance level of p<0.05. Results The median age of 89 patients who underwent CRS + HIPEC was 55 years (range 18- 75). 50 patients are female, 39 patients are male. Peritoneal carcinomatosis was caused by 4 appendiceal neoplasia in 18 patients, colorectal cancer in 38, gastric cancer in 20, and primary peritoneal tumor in 13 patients. The ECOG performance score of all patients was 0-1. Seventy nine (79%) of the patients received perioperative systemic chemotherapy. Lymph node metastasis was detected in 54 patients (61%). The median PCI score of the patients was 14 (range 0-30). Complete cytoreduction (CC-0 or 1) could be performed in 62 patients (70%). Mortality due to surgical complications in the first 30 days after surgery was seen in 5 patients (6%). Complications related to surgery or HIPEC were seen in 32 (36%) patients. Major complications developed in 16 (18%) patients. The postoperative follow-up period of the patients ranged from 1 month to 140 months (11.5 years), and the median follow-up period was 23.2 months. For the whole group (89 patients), 1-year overall survival was 56%, and 3-year survival was 36.%. Progression-free survival (PFS) rates were 80% for 1 year and 43% for 3 years. When PFS was evaluated according to subgroups, PFS was found to be significantly longer in cases of appendiceal and peritoneal PC (p=0.004). In the subgroup analysis performed according to the cytoreduction score, an increase in the CC score resulted in a significantly shorter progression-free survival (p<0.001). In multivariate analysis, cytoreduction score was observed to affect PFS as an independent factor. The median overall survival time (24.1 months) was found to be longer in appendiceal and peritoneal tumors compared to colorectal (10.9 months) and gastric (7.2 months) tumors (p<0.001). While the median overall survival time was 37.9 months in CC-0 patients, 9.2 months in CC-1 patients, 7.8 months in CC-2 patients and 2.2 months in CC-3 patients; It was determined that the patients who received CC-0 had longer overall survival (p<0.001). In the Cox regression analysis, gastric tumors and an increase in the CC score were found to negatively affect overall survival as independent factors. Conclusion In peritoneal carcinomatosis due to gastrointestinal system malignancies, SRC + HIPEC treatment can be applied regardless of the extent of the disease in appendiceal and peritoneal tumors, if the PCI is 20 and below in colorectal cancers, and complete cytoreduction is achieved in gastric tumors in limited carcinomatosis (PCI<10). SRC + HIPEC contributes significantly to progression-free and overall survival in these patients, and long-term survival is observed in 15-20% of patients. Larger, prospective and randomized studies are needed to determine how HIPEC treatment contributes to complete cytoreduction and which of the HIPEC methods will be more effective.