Droplet Digital PCR Measurement of HBV DNA in On-Treatment Chronic HBV Patients: Association With HCC Development and Outcomes.

Low-level residual viremia can be present in chronic hepatitis B (CHB) patients on nucleos(t)ide analogues (NUCs). Due to the detection limits of current HBV DNA assays, the association between residual viremia and HBV-related HCC has not been well studied. This study included NUC-treated HBV-related HCC patients with unquantifiable serum HBV DNA by the conventional Cobas-Taqman assay (< 20 IU/mL) at HCC diagnosis. The HCC patients were matched in a 1:1 ratio with NUC-treated non-HCC controls. Serum samples at the time of HCC diagnosis, 1 year before, and 2 years before diagnosis were retrospectively retrieved and tested for residual viremia by a validated high-sensitivity droplet digital polymerase chain reaction assay (lower limit of detection 1.6 IU/mL). Among 208 patients (104 HCC vs. 104 controls; mean age 63.1, 80.8% male, 54.3% cirrhosis), residual viremia within 2 years was observed in 82.7% of HCC patients and 49.0% of controls (p < 0.001), and was independently associated with HCC occurrence (OR 7.243, 95% CI 1.862-28.170, p = 0.004). In HCC patients, residual viremia was associated with histological microvascular invasion (44.4% vs. 9.1% in patients without residual viremia, p = 0.033) and lower probability of presenting with Barcelona Clinic Liver Cancer stage 0 HCC (OR 0.281, 95% CI 0.094-0.838, p = 0.023). After median follow-up for 7.2 years, residual viremia within 2 years before HCC diagnosis was independently associated with liver-related mortality (HR 4.472, 95% CI 1.212-16.504, p = 0.025). Residual viremia in NUC-treated CHB patients is associated with a higher risk of HCC development, more advanced tumour staging and poorer outcomes. High-sensitivity HBV DNA assays may be utilized for monitoring in NUC treatment.