Conditional Survival Estimates Improve Over Time for Patients with Hepatocellular Carcinoma: An Analysis for Nationwide Korea Cancer Registry Database

PURPOSE: Conditional survival estimates (CSE) can provide additional useful prognostic information on the period of survival after diagnosis, which helps in counseling patients with cancer on their individual prognoses. This study aimed to analyze conditional survival (CS) for hepatocellular carcinoma (HCC) using a Korean national registry. MATERIALS AND METHODS: Patients with HCC, registered in the Korean cancer registry database, were retrospectively reviewed. Overall survival (OS) was calculated using the Kaplan-Meier method. The 1-year CS at X year or month after diagnosis were calculated as CS(1)=OS((X+1))/OS((X)). CS calculations were performed in each Barcelona Clinic Liver Cancer stage, after which patients at stage 0, A, and B underwent subgroup analysis using initial treatment methods. RESULTS: A total of 4,063 patients diagnosed with HCC from January 2008 to December 2010, and 2,721 who were diagnosed from January 2011 to December 2012, were separately reviewed. In 2008-2010, the 1-year CS of 1, 2, 3, 4, and 5-year survivors was 82.9%, 85.1%, 88.3%, 88.0%, and 88.6%, respectively. Patients demonstrated an increase in CSE over time in subgroup analysis, especially in the advanced stages. In 2011-2012, the 1-year CS of 6, 12, 18, 24, 30, and 36 months was 81.5%, 83.8%, 85.3%, 85.5%, 86.5%, and 88.8%, respectively. The subgroup analysis showed the same tendency towards increased CSE in the advanced stages. CONCLUSION: Overall, the CS improved with each additional year after diagnosis in both groups. CSE may therefore provide a more accurate prognosis and hopeful message to patients who are surviving with or after treatment.