PARP1 and hepatocellular carcinoma: HCC tumours with increased PARP1/2 protein expression also exhibited a clinically poorer prognosis, with decreased overall and disease-free survival rates in addition to increased recurrence rates, tumour marker (alpha feto-protein) levels, invasion, metastases and tumour size, supporting a role for PARP1/2 in disease progression [64,66,67].