Insights into synchronous peritoneal metastases from hepatobiliary origin: Incidence, risk factors, treatment, and survival from a nationwide database

Introduction: – This population-based study aimed to investigate incidence, risk factors, treatment, and survival of synchronous peritoneal metastases (PM) of hepatobiliary origin. Methods: – All Dutch patients diagnosed with hepatobiliary cancer between 2009 and 2018 were selected. Factors associated with PM were identified with logistic regression analyses. Treatments for patients with PM were categorized into local therapy, systemic therapy, and best supportive care (BSC). Overall survival (OS) was investigated using log-rank test. Results: – In total, 12 649 patients were diagnosed with hepatobiliary cancer of whom 8% (n = 1066) were diagnosed with synchronous PM (12% [n = 882/6519] in biliary tract cancer [BTC] vs. 4% [n = 184/5248] in hepatocellular carcinoma [HCC]). Factors that were positively associated with PM were the female sex (OR 1.18, 95% CI 1.03–1.35), BTC (OR 2.93, 95% CI 2.46–3.50), diagnosis in more recent years (2013–2015: OR 1.42, 95% CI 1.20–1.68; 2016–2018: OR 1.48, 95% CI 1.26–1.75), T3/T4 stage (OR 1.84, 95% CI 1.55–2.18), N1/N2 stage (OR 1.31, 95% CI 1.12–1.53) and other synchronous systemic metastases (OR 1.85, 95% CI 1.62–2.12). Of all PM patients, 723 (68%) received BSC only. Median OS was 2.7 months (IQR 0.9–8.2) in PM patients. Conclusion: – Synchronous PM were found in 8% of all hepatobiliary cancer patients and occurred more often in BTC than in HCC. Most patients with PM received BSC only. Given the high incidence and dismal prognosis of PM patients, extended research in hepatobiliary PM is needed to achieve better outcome in these patients.