Complete cytoreductive surgery plus HIPEC for peritoneal metastases from unusual cancer sites of origin: results from a worldwide analysis issue of the Peritoneal Surface Oncology Group International (PSOGI)

<p><b>Aim:</b> The aim of this study was to assess the outcomes of patients operated on for peritoneal metastases from unusual cancer sites of origin, meaning apart from peritoneal metastases (PM) from colorectal, gastric and epithelial ovarian carcinomas, pseudomyxoma peritonei and mesothelioma.</p> <p><b>Patients and methods:</b> A questionnaire concerning patients treated with cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) for PM arising from unusual cancer sites of origin was sent to all centres, which routinely performed HIPEC, through the Peritoneal Surface Oncology Group International and the RENAPE network.</p> <p><b>Results:</b> Between September 1990 and June 2016, 850 procedures for unusual cases were performed in 781 patients, in 53 centres worldwide. Nearly two-thirds of the procedures were performed for three indications: rare ovarian carcinoma (<i>n</i> = 224), sarcoma (<i>n</i> = 189) and neuroendocrine tumours (<i>n</i> = 127). The median PCI was 12 [0–39]. Grade III–IV postoperative complications occurred in 272 patients (41%). Nineteen patients (2.9%) died postoperatively. After a median follow-up of 46 months, median overall survival (OS) was 39 months [33.18–44.05]. Five-year OS rate was 38.7%. For the three main indications, 5-year OS was significantly greater in patients with PM from rare ovarian carcinoma (57.7%), than that of patients with PM from neuroendocrine tumours (39.9%), and from sarcoma (29.3%) (<i>p</i> < 0.0001).</p> <p><b>Conclusions:</b> CRS and HIPEC appear to be safe and effective in patients with peritoneal metastases from unusual cancer sites of origin, especially from rare ovarian carcinomas, PM from neuroendocrine tumours. The respective roles of CRS and HIPEC remain unclear and should be evaluated.</p