The Role of Cytoreductive Surgery Plus Hyperthermic Intraperitoneal Chemotherapy (HIPEC) in Peritoneal Metastases...

Background/Objectives: Peritoneal metastases from breast cancer (PMBC) are rare, aggressive, and lack standardized management. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) has emerged as a potential locoregional strategy for highly selected patients. This PRISMA-informed narrative review used a structured and reproducible search and study-selection process, SWiM-guided narrative synthesis, and descriptive pooled individual-patient data (IPD) analysis to evaluate the feasibility, safety, and reported oncologic outcomes of CRS plus HIPEC in PMBC. Methods: The English-language literature was searched in PubMed/MEDLINE, Embase, and Google Scholar up to 31 December 2025. Eligible peer-reviewed full-text articles reported PMBC patients treated with CRS plus HIPEC and at least one perioperative or oncologic outcome. Patient-level data were extracted when explicitly reported and were summarized descriptively; no inferential survival analysis was performed. Risk of bias was assessed using JBI checklists for case reports/series and ROBINS-I for the multicenter cohort. Results: Six peer-reviewed studies were included (66 PMBC patients); 30 patients underwent CRS plus HIPEC. Five studies provided sufficient patient-level data for descriptive pooled IPD analysis (n = 17). Median age at CRS/HIPEC was 56 years (n = 13 with reported age), and the median interval between breast cancer diagnosis and PMBC was 12 years (range 0-30 years; available-case analysis). Median PCI was 21.5 (n = 16), and complete cytoreduction (CC-0) was achieved in 9 of 17 patients. Major postoperative morbidity occurred in 17.6%, while no in-hospital or 30-day mortality was reported. Reported disease-control and survival outcomes were heterogeneous and are therefore summarized only descriptively. In the multicenter cohort, curative-intent CRS with or without HIPEC was associated with a median overall survival of 61.5 months measured from diagnosis of peritoneal metastases; however, HIPEC-specific baseline characteristics and oncologic outcomes were not separately stratified. Conclusions: CRS plus HIPEC appears feasible in highly selected PMBC patients and may be associated with favorable outcomes when complete cytoreduction is achievable. However, the evidence is sparse, heterogeneous, and highly prone to selection and publication bias. Therefore, no causal inference regarding the independent benefit of HIPEC can be drawn, and this approach should be considered investigational pending prospective multicenter registries.