Thrombocytosis is associated with worse survival in patients with hepatocellular carcinoma

Background & Aims: Thrombocytosis is associated with more aggressive tumour biology in many malignancies. There are limited data in patients with hepatocellular carcinoma (HCC), which often occurs in patients with cirrhosis and portal hypertension. We aimed to explore the prognostic value of thrombocytosis in two cohorts of patients with HCC. Methods: We included 3561 patients from Taiwan and 1145 patients from the USA. Thrombocytopenia was defined as platelet count < 150×10⁹/L and thrombocytosis as ≥ 300 × 10⁹/L at HCC diagnosis. We used multivariable Cox proportional hazard models to identify independent predictors of survival. Results: Thrombocytosis was present in 9.0% and 6.9% of Taiwan and USA patients respectively. Compared to patients with normal platelet counts and those with thrombocytopenia, patients with thrombocytosis had larger tumours, increased vascular invasion and a higher proportion had extrahepatic metastases in both cohorts. In multivariable analysis, thrombocytosis (aHR 1.40, 95% CI 1.23-1.60) and thrombocytopenia (aHR 1.13, 95% CI 1.04-1.23) were both associated with worse survival after adjusting for age, gender, liver disease aetiology, Child-Pugh score, maximal tumour size, tumour nodularity, vascular invasion, lymph node or distant metastasis, performance status and alpha-fetoprotein level. Patients with thrombocytosis had a median survival of 6 and 4 months in the Taiwan and USA cohorts, compared to 32 and 14 months for those with normal platelet counts and 38 and 16 months for thrombocytopenic patients. Conclusion: Thrombocytosis is independently associated with increased tumour burden and worse overall survival among HCC patients.