Evolution of etiology, presentation, management and prognostic tool in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death worldwide, but its current status is unclear. We aimed to investigate the evolution of etiology, presentation, management and prognostic tool in HCC over the past 12 years. A total of 3349 newly diagnosed HCC patients were enrolled and retrospectively analyzed. The comparison of survival was performed by the Kaplan-Meier method with the log-rank test. Hepatitis B and C virus infection in HCC were continuously declining over the three time periods (2004–2007, 2008–2011, 2012–2015; p < 0.001). At diagnosis, single tumor detection rate increased to 73% (p < 0.001), whereas vascular invasion gradually decreased to 20% in 2012–2015 (p < 0.001). Early stage HCC gradually increased from 2004–2007 to 2012–2015 (p < 0.001). The probability of patients receiving curative treatment and long-term survival increased from 2004–2007 to 2012–2015 (p < 0.001). The Cancer of Liver Italian Program (CLIP) and Taipei Integrated Scoring (TIS) system were two more accurate staging systems among all. In conclusion, the clinical presentations of HCC have significantly changed over the past 12 years. Hepatitis B and C virus-associated HCC became less common, and more patients were diagnosed at early cancer stage. Patient survival increased due to early cancer detection that results in increased probability to undergo curative therapies.

Diagnosis and definitions. The diagnosis of HCC was based on the findings of typical radiological features contrast-enhanced dynamic computed tomography (CT) and magnetic resonance imaging (MRI) or histology confirmed if atypical radiological features 3,14 . The performance status was evaluated by using Eastern Cooperative Oncology Group (ECOG) scale: 0 (asymptomatic) to 4 (confined to bed) 18 . All clinical data analyzed in this study were recorded at the time of diagnosis.

Surveillance. Current practice guidelines from the American Association for the Study of Liver Diseases
(AASLD), European Association of the Study of Liver Diseases (EASL) and Asia-Pacific Association of the Study of Liver diseases (APASL) recommend surveillance for patients at high risk for hepatocellular carcinoma 2,3,5 . The combined use of serum ɑ-fetoprotein (AFP) level and abdominal sonography was regularly performed every 4-6 months for screening high-risk subjects including chronic hepatitis B and C, and subclinical or overt cirrhosis 2,19 . treatment. The newly diagnosed HCC patients at Taipei Veterans General Hospital were discussed in the multidisciplinary board for diagnosis confirmation and treatment recommendation. The criteria of surgical resection for HCC were (1) patients with tumor involving no more than three Healey's segments, (2) Child-Turcotte-Pugh (CTP) class A with less than 25% of retention of indocyanine green 15 min after injection, and (3) no main portal trunk invasion or distant metastasis 20 . Radiofrequency ablation (RFA) was indicated in patients who had preserved liver function but were not eligible for surgical resection 17,21 . Transarterial chemoembolization (TACE) was performed in patients who had unresectable lesions or unwilling to receive curative treatment in the absence of distant metastasis and hepatic decompensation 14 . Systemic therapy or targeted therapy was given to selected patients with adequate liver functional reserve 3,14 . For patients with poor liver functional reserve or decreased performance status, best supportive care was given. Shared-decisions were made between physicians and patients prior to initiation of any definite treatment. In this study, resection, ablation and liver transplantation were classified as curative treatments. Other managements were collectively labeled as non-curative treatments. cancer staging. According to the AASLD and EASL HCC management guidelines, the Barcelona Clínic of Liver Cancer (BCLC) is endorsed as the standard staging system for HCC 3,14 . In addition, the prognostic power for HCC among the Cancer of the Liver Italian Program (CLIP), tumor-node-metastasis (TNM) system, Tokyo score, Japan Integrated Scoring (JIS) system, Taipei Integrated Scoring (TIS) system, and Hong Kong Liver Cancer (HKLC) staging system was also compared in this study 22-25 . Statistics. The Chi-squared test and two-tailed Fisher exact test were used to compare categorical data. The Mann-Whitney ranked sum test or Kruskal-Wallis test was used to compare continuous variables between different groups. Data were expressed as the mean ± standard deviation (SD) and median with interquartile range (IQR). The comparison of survival distribution was performed by the Kaplan-Meier method with the log-rank test. Corrected Akaike information criteria (AICc) was obtained to reveal how the staging system correlated with patient's survival. The AICc was chosen over Akaike information criteria to compensate for the different number of parameters in each staging system. Homogeneity was measured by χ2 test to evaluate the differences in survival among patients in the same stage within each system 26 . The lower AIC, the more explanatory and informative the staging system is 27 . A p-value < 0.05 was considered statistically significant by 2-tailed tests. All statistical analyses were performed using IBM SPSS Statistics for Windows, Version 21.0 (IBM Corp., Armonk, NY, USA).

Results
Baseline characteristics and staging. A total of 3349 newly diagnosed HCC patients were consecutively identified during the study period. Their baseline characteristics and clinical information are shown in Table 1    www.nature.com/scientificreports www.nature.com/scientificreports/   www.nature.com/scientificreports www.nature.com/scientificreports/ 2008-2011 cohort, and 56%, 37%, 33% for 2012-2015 cohort, respectively, in patients beyond the Milan criteria. Significant survival distributions were found in three different periods of HCC patients for both groups (Fig. 4A,B; p < 0.001).

Discussion
Our study shows that there was 13.1% reduction and 20.3% further reduction in the incident cases of HCC from 2004-2007 (n = 1308) to 2008-2011 (n = 1136), and from 2008-2011 to 2012-2015 (n = 905), respectively. HBV is one of the etiologies of liver cirrhosis and HCC. The incidence of HBV-related HCC declined in this 12-year study period. Consistent with previous cohort studies 6,8,9 , HBV infection significantly decreased after the implementation of the vaccination program 8,9 . Notably, the impact of national HBV vaccination program not only reduced the carrier rate of HBsAg, but also decreased the incidence of HBV-related HCC.  High levels of serum HBsAg and DNA are tightly associated with the occurrence of HCC [28][29][30] . Antiviral therapy using nucleoside or nucleotide analogues may inhibit HBV replication, and leads to improvement in liver histology and reduced risk of HCC 12,31 . In addition to HBV, HCV is also another risk factor for HCC globally 32 . Antiviral therapy for hepatitis C with interferon and ribavirin results in improved clinical outcomes by decreasing the risk of hepatic decompensation and HCC 33 . Alternatively, the development of cirrhosis is associated with non-alcoholic steatohepatitis (NASH). In addition, metabolic syndrome such as diabetes and obesity, could increase the risk of HCC in NASH patients 2,3 . In our study, the percentage of cryptogenic cause of HCC increased from 14% in 2004-2007 to 20% in 2012-2015; suggesting NASH may play an important role in inducing HCC.
The changing incidence of HCC in the international setting revealed that the incidence of HBV-related HCC has declined in most Asian countries such as China, Philippines and South Korea after the implementation of HBV vaccination. The decreasing rate of HCV-related HCC was reported in Japan and Italy due to specific antiviral therapy, including direct acting antiviral agents. The increasing rates of cryptogenic HCC were observed in US, Western countries and some Asian countries possibly due to the emergence of metabolic syndrome and non-alocholic steatohepatitis (NASH) 34 . These results are mostly consistent with our single center study in Taiwan.
The diagnosis of early stage HCC increased from 33% in 2004-2007 to 37% in 2012-2015 in this survey. The percentage of patients receiving curative treatment also increased from 44% in 2004-2007 to 55% in 2012-2015. Previous studies suggested that serum AFP and abdominal sonography were useful screening tools in high risk patients 2,35 . Our data were consistent with previous study 36 , indicating that screening patients with known risk factors may result in early cancer detection. Consistently 37,38 , our results also show that there is increased long-term survival in HCC patients because of a higher rate of curative treatments, including surgical resection and local ablation therapy.
The key prognostic predictors for HCC are liver functional reserve, tumor burden and therapeutic strategy. We further performed a subgroup analysis to delineate the pattern and cause of a better long-term survival in the 2012-2015 cohort. Importantly, we found that such survival impact is independent of CTP class, Milan criteria and treatment modality. An overall improvement in antiviral therapy for chronic viral hepatitis, cancer detection and active anti-cancer therapy over the study period may greatly contribute to the survival advantage 36,37 .
To date, several HCC staging systems have been implemented for prognostic prediction. However, the optimal staging system has been in intense debate for a decade. Our results suggest that the CLIP score was the best staging system for prognostic prediction in the cohort of 2004-2007 and 2008-2011. However, TIS system is a better system in discriminating clinical outcomes than the other 6 models for the 2012-2015 cohort. This discrepancy could be due to the change in patient demographics and pattern of treatment strategy, and also well explains why published studies addressing this issue revealed discordant results.
Our study has some limitations. First, this is a single center study in an area where HBV is commonly seen, which is different from Western countries. Second, selection bias could not be completely avoided because of the retrospective nature of this study. Third, a direct causal relationship between the changes of disease presentation and patient outcome cannot be confidently confirmed. Further studies are needed to validate our result.
In conclusion, the characteristics of patients with HCC have significantly changed over the last 12 years. HBV-and HCV-associated HCC became less common and cryptogenic HCC, probably related to NASH, was increasing. Early cancer detection and implementation of active anti-cancer treatment become possible and can be expected to prolong the long-term survival of HCC patients further.