Peritoneal metastases (PM) are observed in approximately 8% of patients diagnosed with colorectal cancer, either synchronously or metachronously during follow-up. PM often manifests as the sole site of metastasis. PM is associated with a poor prognosis and typically shows resistance to systemic chemotherapy. Consequently, there has been a search for alternative treatment strategies. This review focuses on the global evolution of the combined approach involving cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for the management of PM. It encompasses accepted clinical guidelines, principles for patient selection, surgical and physiological considerations, biomarkers, pharmacological protocols, and treatment outcomes. Additionally, it integrates the relevant literature and findings from previous studies. The role of CRS and HIPEC, in conjunction with other therapies such as neoadjuvant and adjuvant chemotherapy, is discussed, along with the management of patients presenting with oligometastatic disease. Furthermore, potential avenues for future development in this field are explored.

Background: The treatment for patients with colorectal cancer with metastases to the peritoneum is complex and may involve both surgery and chemotherapy. Circulating tumor cells (CTCs) have been poorly investigated in peritoneal metastatic colorectal cancer. The aim of the study is to examine the role of CTCs as a biomarker for monitoring disease progression, treatment response, and residual disease using CellMate – a new promising in vitro diagnostic platform technology. Materials and methods: The authors prospectively followed the clinical outcomes of 46 patients treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for colorectal cancer with peritoneal metastases and examined whether CTCs were present the week of surgery. The CTC measurements were made with the CellMate technology, which is a platform technology to detect CTCs based on the difference in biomechanical properties compared to blood resident cells. The study was registered online (ClinicalTrials.gov). Results: CTCs were detected in 17 (37%) patients. The presence of CTCs was associated with shorter recurrence-free survival and overall survival after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. Both recurrence-free survival (HR 4.00, 95% CI: 1.15–13.9; P=0.029) and overall survival (HR 5.91; 95% CI: 1.18–29.7; P=0.03) were significantly worse if CTCs were detected after neoadjuvant treatment. In the subgroup of patients with CTCs detected, adjuvant therapy tended to improve the prognosis while in CTC negative patients it did not. Conclusions: Pending a prospective multicenter trial to validate these findings, CTCs may in the future be used as a dynamic personalized biomarker for prognostication, predicting response to therapy, and for monitoring disease progression in colorectal cancer with metastases to the peritoneum.

Appendiceal tumors are uncommon and, at times, discovered incidentally during histological examination. The histopathological classification of the disease is complex and has generated some controversy. The analysis of circulating tumor cells can be used for the early detection of metastatic potential. The aim of the present study was to examine the prognostic value of circulating tumor cells in patients with appendiceal tumors and peritoneal metastases. To our knowledge, this is the first study to examine CTCs in appendiceal tumors. We performed a prospective cohort study of consecutive patients treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy between 2015 and 2019 at a HIPEC referral center. In total, 31 patients were included in the analysis, and circulating tumor cells were detected in 15 patients (48%). CTC positivity was not associated with overall or recurrence-free survival, nor was it correlated with PCI score or histopathological grading. Surprisingly, however, CTCs were found in almost half the patients. The presence or quantities of these cells did not, on their own, predict systemic metastatic potential during the observed time, and they did not appear to significantly correlate with the oncological outcomes recorded.

Purpose: Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRSH) or liver resection have led to increased survival in patients with peritoneal or liver metastases of colorectal cancer. Selected patients undergo concomitant CRSH and liver resection. Differences in survival and morbidity between patients who underwent concomitant surgery, CRSH or liver resection for peritoneal and/or liver metastases were compared. Methods: Patients who underwent liver resection and/or CRSH for colorectal liver and/or peritoneal metastases, 2006–2016, were included. Regression analysis was used to evaluate the associations between baseline characteristics and survival. Results: Overall, 634 patients were studied. Twenty-eight patients had peritoneal and liver metastases, 121 patients had peritoneal metastases only, and 485 patients had isolated liver metastases. Median survival after concomitant treatment was 23.8 months (95% CI 12.8–43.8), after CRSH 34.5 months (95% CI 27.1–41.9), and after liver resection 54.2 months (95% CI 47.4–61.0) (p < 0.001). Increased hepatic tumor burden (HR 3.2, 95% CI 1.8–5.8) and high-volume peritoneal disease (HR 6.0, 95% CI 3.7–9.8) were associated with decreased survival in multivariate analysis. Postoperative complications according to a Clavien–Dindo score > 3a were observed in 11% in the liver resection group, 15% in the CRSH group, and 11% in the concomitant treatment group (p = 0.945). Conclusions: Patients treated with concomitant surgery for liver and peritoneal metastases experienced a shorter median overall survival than patients treated for metastases at an isolated site but had a similar rate of severe postoperative complications. The extent of peritoneal spread seemed to impact survival more than the tumor burden in the liver.