[Cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy for pseudomyxoma peritonei: results from a...

Objective: To evaluate long-term survival, perioperative severe adverse events, and prognostic factors in pseudomyxoma peritonei (PMP) treated with cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy (CRS+HIPEC) in a multicenter real-world cohort. Methods: This was a retrospective observational study. Based on a multicenter joint database, clinicopathological data were collected from 940 patients with PMP who underwent CRS+HIPEC between January 2004 and November 2025 across four hospitals in the Peritoneal Oncology Specialty Alliance: Beijing Shijitan Hospital, Capital Medical University (n=532), Beijing Tsinghua Changgung Hospital, Tsinghua University (n=388), Zhongnan Hospital of Wuhan University (n=18), and Shijiazhuang People's Hospital (n=2).Long-term survival and perioperative severe adverse events were documented in this PMP cohort. Cox regression was used to identify independent prognostic risk factors, and interaction tests as well as stratified joint-effect analyses were performed. Results: A total of 418 (44.5%) males and 522 (55.5%) females were included, among whom 348 (37.0%) patients were aged ≥60 years. Histopathological types were as follows: acellular mucin in 20 cases (2.1%), low-grade PMP in 511 cases (54.4%), high-grade PMP in 302 cases (32.1%), and high-grade PMP with signet ring cells in 107 cases (11.4%). A total of 587 patients (62.4%) received CRS+HIPEC for the first time. The median operative time was 592 (range, 120-1080) minutes. A total of 695 patients (73.9%) had a peritoneal cancer index (PCI) score ≥20, and 434 patients (46.2%) had a completeness of cytoreduction (CC) score of 2-3. The incidence of perioperative severe adverse events was 27.0% (254/940). The median follow-up duration of this cohort was 39.6 (0.5-254.6) months, and the median overall survival (OS) was 116.7 months (95%CI: 99.2-134.1). Multivariate Cox regression analysis revealed that body mass index (HR=0.92, P<0.01), history of abdominal surgery (HR=0.40, P<0.01), number of organ resections (HR=0.58, P<0.01), PCI score (HR=1.65, P=0.04), CC score (HR=1.37, P=0.03), intraoperative blood loss (HR=1.00, P=0.03), pathological subtype (HR=1.90, P<0.01), Ki-67 index (HR=1.67, P=0.01), preoperative carcinoembryonic antigen (CEA) (HR=1.45, P=0.03), preoperative carbohydrate antigen 125 (CA125) (HR=2.31, P<0.01), postoperative CEA (HR=1.45, P=0.03), and lymph node metastasis (HR=1.88, P<0.01) were independent prognostic factors. Interaction testing showed that the risk of death was significantly increased in patients with PCI ≥20 and CC score 2-3 (HR=2.32, 95%CI: 1.46-3.67, P<0.01); significantly decreased in patients with normal preoperative CEA and ≥2 organ resections (HR=0.31, 95%CI: 0.15-0.62, P<0.01); and significantly increased in patients with Ki-67 >15% and normal preoperative CEA (HR=6.34, 95%CI: 1.50-26.84, P=0.03). Conclusions: CRS+HIPEC can provide favorable long-term survival benefits for patients with PMP. Tumor burden, quality of cytoreduction, proliferation index, tumor markers, and number of organ resections are independently associated with prognosis.