Retrospective Analysis of Patients with Signet Ring Subtype of Colorectal Cancer with Peritoneal Metastasis Treated with CRS & HIPEC

Signet ring cell subtype (SRC) of colorectal cancer (CRC) is a rare subtype and occurs in approximately 1% of all patients with CRC. Patients with peritoneal metastasis (PM) of SRC have a poor prognosis, and this subtype is frequently considered as a contra-indication for extensive surgical treatment. This retrospective study from two dedicated peritoneal surface malignancy centers in Japan included all patients treated with CRS ± hyperthermic intraperitoneal chemotherapy (HIPEC) between July 1994 and December 2017 from a prospectively maintained database. Preoperative, operative, and postoperative parameters were recorded, including complication rates and follow-up. Sixty of the 320 patients treated with CRS due to CRC were diagnosed with SRC subtype. The mean age of the patients was 51.4 years, and the mean peritoneal carcinomatosis index (PCI) was 13.1. Complete cytoreduction was achieved in 61.7% of cases. The postoperative morbidity rate was 25% and the mortality rate was 1.7%. The median overall survival (OS) was 14.4 months. Cox regression analysis revealed small bowel PCI > 2 (hazard ratio (HR) 6.5; p = 0.008) as the most important factor for OS. With accurate patient selection (e.g., PCI ≤ 12 or small bowel PCI ≤ 2), even patients with PM of CRC with SRC subtype may benefit from CRS and HIPEC, with median OS from 17.8 to 20.8 months and 5-year OS of 11.6%

Peritoneal mesothelioma

This review provides an overview of articles about peritoneal mesothelioma (PM) to analyze the effect of treatment modalities on response rates, post-treatment side effects, morbidity and mortality, and survival. Median survival in months following systemic chemotherapy (SC) ranged from 8.7 to 26.8 months. However, no patient was reported to have survived for more than five years with SC alone. In contrast, comprehensive treatment that included cytoreductive surgery (CRS) + perioperative chemotherapy (POC) showed a significantly longer median survival time than SC alone. Additionally, CRS + POC demonstrated 10-year survival rates of 12%-35%. Accordingly, CRS + POC is an innovative treatment that provides long-term survival in selected patients with PM. Selection criteria are performance status (ECOG PS ≤ 1), the absence of extraperitoneal metastasis, PCI less than cutoff levels (from < 10 to < 28), MIB-1 index (< 10), and histologic type (epithelioid type). Postoperative morbidity and mortality rates after CRS + POC were significantly higher than with more conventional operations. Accordingly, CRS and POC should be done at the specialized peritoneal surface malignancy centers

The Development of Peritoneal Metastasis from Gastric Cancer and Rationale of Treatment According to the Mechanism

In the present article, we describe the normal structure of the peritoneum and review the mechanisms of peritoneal metastasis (PM) from gastric cancer (GC). The structure of the peritoneum was studied by a double-enzyme staining method using alkaline-phosphatase and 5′-nucreotidase, scanning electron microscopy, and immunohistological methods. The fundamental structure consists of three layers, mesothelial cells and a basement membrane (layer 1), macula cribriformis (MC) (layer 2), and submesothelial connective tissue containing blood vessels and initial lymphatic vessels, attached to holes in the MC (layer 3). Macro molecules and macrophages migrate from mesothelial stomata to the initial lymphatic vessels through holes in the MC. These structures are characteristically found in the diaphragm, omentum, paracolic gutter, pelvic peritoneum, and falciform ligament. The first step of PM is spillage of cancer cells (peritoneal free cancer cells; PFCCs) into the peritoneal cavity from the serosal surface of the primary tumor or cancer cell contamination from lymphatic and blood vessels torn during surgical procedures. After PFCCs adhere to the peritoneal surface, PMs form by three processes, i.e., (1) trans-mesothelial metastasis, (2) trans-lymphatic metastasis, and (3) superficial growing metastasis. Because the intraperitoneal (IP) dose intensity is significantly higher when generated by IP chemotherapy than by systemic chemotherapy, IP chemotherapy has a great role in the treatment of PFCCs, superficial growing metastasis, trans-lymphatic metastasis and in the early stages of trans-mesothelial metastasis. However, an established trans-mesothelial metastasis has its own interstitial tissue and vasculature which generate high interstitial pressure. Accordingly, it is reasonable to treat established trans-mesothelial metastasis by bidirectional chemotherapy from both IP and systemic chemotherapy

Photodynamic Detection of Peritoneal Metastases Using 5-Aminolevulinic Acid (ALA)

In the past, peritoneal metastasis (PM) was considered as a terminal stage of cancer. From the early 1990s, however, a new comprehensive treatment consisting of cytoreductive surgery and perioperative chemotherapy has been established to improve long-term survival for selected patients with PM. Among prognostic indicators after the treatment, completeness of cytoreduction is the most independent predictors of survival. However, peritoneal recurrence is a main cause of recurrence, even after complete cytoreduction. As a cause of peritoneal recurrence, small PM may be overlooked at the time of cytoreductive surgery (CRS), therefore, development of a new method to detect small PM is desired. Recently, photodynamic diagnosis (PDD) was developed for detection of PM. The objectives of this review were to evaluate whether PDD using 5-aminolevulinic acid (ALA) could improve detection of small PM