Background: Interferon-free direct-acting antivirals (DAA) have markedly increased the sustained virological response (SVR) rate among patients with hepatitis C. Although DAA inhibit the development of hepatocellular carcinoma (HCC), predictive factors remain unclear. The aims of the present study were to investigate predictive factors for HCC occurrence and recurrence after SVR by DAA in prospectively followed patients with hepatitis C (HCV).
Methods: One hundred and eighty-three HCV-infected patients treated with DAA and achieving SVR were prospectively followed up for more than one year. Among these patients, 166 had no history of HCC before DAA therapy, while 17 had a history of being treated for HCC by radiofrequency ablation or resection before the initiation of DAA. Liver stiffness (LS) measurements were conducted using transient elastography, and LS was assessed at the initiation of DAA (LS0), 24 weeks after the initiation of DAA (LS24), 48 weeks after (LS48), and every year after that.
Results: HCC occurred in 7 out of 166 patients without a history of HCC (4.2%), and recurred in 9 out of 17 with a history of HCC (52.9%). Patients with a history of HCC were significantly older, mainly males, had higher alpha-fetoprotein (AFP) levels before DAA and at SVR24, higher Fib-4 levels, and higher LS0, 24, and 48 than those without a history of HCC. Age (p = 0.013) and AFP at SVR24 (p = 0.036) correlated with occurrence. LS48 (p = 0.043) correlated with recurrence.
Conclusions: Predictive factors differed between HCC occurrence and recurrence after SVR by DAA in HCV patients. High recurrence rates were due to fibrosis in the liver being more advanced in patients with than in those without a history of HCC. Age and AFP at SVR24 were identified as predictive factors of HCC occurrence and LS48 of HCC recurrence.
Predictive Factor HCC Occurrence and Recurrence SVR DAA1. Introduction
Chronic hepatitis C (HCV) is an important risk factor for the development of hepatocellular carcinoma (HCC). Interferon (IFN)-free direct-acting antivirals (DAA) have markedly increased the sustained virological response (SVR) rate to more than 90% in patients with HCV [1] [2] [3] [4] [5]. Previous studies reported that SVR by DAA effectively reduced the risk of HCC [6] [7] [8]. On the other hand, DAA has been reported to increase the risk of HCC in patients with HCV, particularly in those receiving DAA after the treatment of HCC, namely, HCC recurrence [9]. HCC may develop after SVR by DAA because it has been reported to occur even after SVR by IFN-based therapy. Risk factors for the development of HCC need to be identified in recent DAA therapies. Some risk factors after SVR by IFN-based therapy in patients without HCC, namely, HCC occurrence, include an older age, male gender, severe fibrosis, diabetes mellitus, and elevated alpha-fetoprotein levels (AFP) [10] - [17]. While AFP [18], Wisteria floribunda agglutinin-positive Mac-2 binding protein [19], and TLL1 [20] are known prognostic factors of HCC occurrence and recurrence in HCV-positive patients after SVR by DAA, there may be other prognostic factors that are yet to be identified. The aims of the present study were to investigate predictive factors for HCC occurrence and recurrence after SVR by DAA in prospectively followed patients with HCV.
2. Materials and Methods
In the present study, 201 HCV-infected patients treated with DAA between September 2014 and July 2018 and achieving SVR were prospectively followed up for more than one year at Department of Gastroenterology, National Hospital Organization Nagoya Medical Center, Nagoya, Japan. These patients were treated with daclatasvir plus asunaprevir 39, sofosbuvir plus ledipasvir 55, sofosbuvir plus ribavirin 42, ombitasvir plus paritaprevir with ritonavir 6, elbasvir plus grazoprevir 9, and pibrentasvir plus glecaprevir 32. Patients with decompensated cirrhosis, autoimmune hepatitis, primary biliary cirrhosis, and co-infection with hepatitis B virus were not included in the present study. Patients co-infected with human immunodeficiency virus (HIV) were also excluded because HIV co-infection increases the severity of hepatitis C [21]. Therefore, 183 patients were enrolled and prospectively followed up for more than one year (Figure 1). Among the 183 patients, 166 had no history of HCC before DAA therapy and 17 had a history of being treated for HCC by radiofrequency ablation (RFA) or resection and achieved complete responses before the initiation of DAA.
Blood chemistry examinations for all patients were conducted every two weeks after the initiation of DAA to detect adverse events and every 6 months after DAA therapy. Virological responses were assessed 24 weeks after the completion of treatment. SVR24 was defined as undetectable serum HCV RNA 24 weeks after the completion of treatment. All patients were confirmed to have no HCC tumor using abdominal contrast-enhanced computed tomography (CT) or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MR) and ultrasound (US) before the initiation of DAA. CT or MR was performed every 6 months before DAA and during the follow-up. HCC was diagnosed by a positive result for vascular patterns, as shown in CT or MR. Transient elastography (Fibroscan®) with liver stiffness (LS) measurements was performed using the M probe at a skin-liver capsule distance of less than 20 mm and XL probe of more than 20 mm [22]. Ten validated measurements were performed on each patient and a success rate of least 60% was considered to be reliable. LS were measured at the initiation of DAA (LS0), 24 weeks after the start of DAA (LS24), 48 weeks after (LS48), and every year after that (LS2y, LS3y, and LS4y).
Statistical analysis
Quantitative variables were shown as medians (minimum-maximum). Laboratory data were compared using the Student’s t-test (parametric data) and
chi-squared test. p < 0.05 was considered to be significant. The HCC development rate was calculated using the Kaplan-Meier technique. LS0, LS24, LS48, LS2y, and LS3y were compared using the Mann-Whitney U test. To identify factors associated with HCC occurrence and recurrence, gender was compared by the chi-squared test and age, AFP before DAA, AFP at VR24, Fib-4, LM0, LS24, and LS48 by a logistic regression analysis. According to a Diagnostic performance plot (DP-plot) analysis [23], an optical common cut-off value was selected by Youden’s index of receiver operating characteristic (ROC) curve analysis. Sensitivity, specificity, and accuracy were calculated at the common cut-off point for each factor. Statistical analyses were performed using the Statistical Package for Social Science software v.22 (SPSS, Chicago, IL) in the Sugimoto Data Analysis Service.
3. Results
Profiles of patients with and without a history of HCC
The baseline characteristics of patients included in the present study are shown in Table 1.
Patients with a history of HCC were significantly older (median age, 71 vs. 65 years, p < 0.001), mainly males (p < 0.001), had higher AFP levels before DAA and at SVR24 (9.0 vs. 4.0 ng/ml and 6.0 vs. 3.0 ng/ml, p < 0.001), higher Fib-4 levels (4.35 vs. 2.52, p < 0.001), and higher LS0, 24, and 48 (16.1 vs. 7.5 kPa, 14.8 vs. 5.8 kPa, 12.0 vs. 5.0 kPa, p < 0.001) than those without a history of HCC. Thus, fibrosis in the liver was more advanced in patients with than in those without a history of HCC.
HCC was detected in 7 out of 166 patients without a history of HCC (4.2%), and recurred in 9 out of 17 with a history of HCC (52.9%).
HCC development
One-, 2-, 3-, and 4-year HCC development rates were 35%, 53%, 53%, and 53%, respectively, for recurrence and 1.4%, 3.0%, 5.4%, and 6.8%, respectively, for occurrence. Figure 2(a) shows the clinical course of HCC occurrence in 7 patients without a history of HCC before the DAA treatment. HCC was detected 12 - 36 months between DAA therapy and occurrence. HCC nodules were diagnosed by CT or MR and were 23 - 20 mm in diameter. Figure 2(b) shows a patient with a history of HCC before DAA, but without recurrence for 29 - 57 months. The period between previous HCC therapy and DAA therapy was 3 - 12 months. Only one HCC nodule was present in each patient at previous HCC and was diagnosed by CT or MR. Previous HCC ranged between 12 and 30 mm in diameter. HCC therapies were RFA for five patients and hepatic resection for three. Figure 2(c) shows a patient with a history of HCC before DAA and recurrence was detected 4 - 16 months after DAA therapy. The period between previous HCC therapy and DAA therapy was 3 - 87 months. Only one HCC nodule was present in each patient at previous HCC and was diagnosed by CT or MR. Previous HCC ranged between 13 and 25 mm in diameter. HCC therapies were
*Median (range), NS: not significant, LS0: LS at the initiation of DAA, LS24, 48: LS 24, 48 months after DAA, DCV/ASV: daclatasvir plus asunaprevir, SOF/RBV: sofosbuvir plus ribavirin, SOF/LDV: sofosbuvir plus ledipasvir, OBV/PTV/rit: ombitasvir plus paritaprevir with ritonavir, EBR/GZR: elbasvir plus grazoprevir, PIB/GLE: pibrentasvir plus glecaprevir, RFA: radiofrequency ablation.
RFA for four patients and hepatic resection for five. Three patients died of HCC.
Analysis to identify factors associated with HCC occurrence and recurrence
We examined factors associated with HCC occurrence and recurrence. Gender was not significant for occurrence or recurrence (Table 2). Age (p = 0.013) and AFP at SVR24 (p = 0.036) correlated with occurrence, whereas AFP before DAA, Fib-4, LM0, LS24, and LS48 did not. LS48 (p = 0.043) correlated with recurrence, whereas age, AFP before DAA, AFP at SVR24, Fib-4, LM0, and LS24 did not (Table 3).
Since the univariate analysis identified factors associated with HCC occurrence and recurrence, we assessed their cut-off values for predicting HCC occurrence and recurrence using a DP-plot analysis. Regarding HCC occurrence, cut-off values for age and AFP at SVR24 were 70.1 years and 4.6 ng/ml, respectively (Figure 3(a)). Concerning HCC recurrence, LS0, LS24, and LS48 cut-off values were 16.2, 14.8, and 11.4 kPa, respectively (Figure 3(b)).
Analysis to identify factors associated with HCC occurrence and recurrence (the chi-squared test)
Characteristics
Occurrence p
Recurrence p
Gender
0.415
0.299
Analysis to identify factors associated with HCC occurrence and recurrence (a logistic regression analysis)
Characteristics
Occurrence
Recurrence
p
p
partial regression coefficient (95% CI)
partial regression coefficient (95% CI)
Age
0.013
0.177
0.050
−0.077
(0.050 - 10.039)
(−0.189 - 0.828)
AFP before DAA
0.760
0.442
−0.005
0.034
(−0.041 - 0.960)
(−0.038 - 0.963)
AFP at SVR24
0.036
0.105
0.126
0.267
(0.008 - 1.008)
(−0.056 - 0.945)
Fib-4
0.795
0.173
−0.049
0.339
(−0.421 - 0.657)
(−0.149 - 0.862)
LS0
0.287
0.067
0.050
0.224
(−0.041 - 0.960)
(−0.014 - 0.987)
LS24
0.413
0.068
0.053
0.200
(−0.074 - 0.929)
(−0.014 - 0.986)
LS48
0.092
0.043
0.104
0.519
(−0.017 - 0.983)
(0.016 - 1.016)
LS0: LS at the initiation of DAA, LS24, 48: LS 24, 48 months after DAA.
Variations in LSM during the follow-up
Figure 3 shows the courses of LSM in all patients.
The course of LS in 159 patients without a history of HCC before DAA and who did not develop HCC is shown in Figure 4(a). LS0, LS24, LS48, LS2y, LS3y, and LS4y median values were 7.1, 5.8, 4.8, 4.7, 4.3, and 4.6 kPa, respectively, showing significant improvements. Seven out of 166 patients subsequently developed HCC, and their LS0, LS24, LS48, and LS2y median values were 10.4, 8.7, 6.8, and 5.8 kPa respectively (closed squares), as shown in Figure 4(b). The course of LS in eight patients with a previous history of HCC treatments and no recurrence is shown in Figure 4(c). Their LS median values also significantly improved: LS0, LS24, LS48, LS2y, and LS3y values were 12.3, 14.8, 8.1, 8.0, and 6.1 kPa, respectively. Nine out of 17 patients subsequently developed HCC, and LS0, LS24, LS48, and LS2y median values were 19.1, 16.9, 16.0, and 14.4 kPa, respectively (closed circle), as shown in Figure 4(d).
4. Discussion
IFN-free DAA therapy has markedly increased the SVR rate among patients with HCV to more than 90%, even under unfavorable conditions, such as elderly patients and those with advanced fibrosis [1] [2] [3] [4] [5]. However, a high rate of HCC recurrence after DAA therapy in patients with a previous history of HCC treatments has been reported [9]. The effects of DAA therapy after SVR on HCC occurrence and recurrence have been unclear; however, Nagata et al. concluded in 2017 that post-SVR HCC occurrence and recurrence were similar between IFN-based and IFN-free treatments [8]. Some patients after SVR by DAA therapy develop HCC. We hypothesized that LS, as an indicator of liver fibrosis, may be involved in HCC occurrence and recurrence and investigated the predictive factors of HCC occurrence and recurrence after SVR by DAA in prospectively followed patients with HCV.
Our patients with a history of HCC were significantly older, had higher AFP and Fib-4 levels, and higher LS values than those without a history of HCC. These results indicate fibrosis in the liver was more advanced in patients with than in those with a history of HCC. LS48 values correlated with recurrence. Although LS0 and LS24 values were not significantly correlated with recurrence, the association we observed (p = 0.067 and 0.067, respectively) may become significant with a larger sample size for patients with a history of HCC. Regarding HCC recurrence, LS0, LS24, and LS48 cut-off values were 16.2, 14.8, and 11.4 kPa, respectively, showing a poor regression. Patients who achieved SVR by IFN-based treatments showed the significant regression of LS [24]. LS values in patients who achieved SVR by DAA also significantly decreased during the follow-up period [25] [26]. This early improvement in LS (from LS0 to LS24) was attributed to a decrease in inflammation in liver tissue. Even in patients with and without a history of HCC, LS values significantly decreased during the follow-up. Since increases in LS due to artifacts associated with liver inflammation were no longer observed at LS24 and LS48, decreases at LS24 and LS48 were considered to reflect the true attenuation of liver fibrosis. However, LS0, 24, and 48 values were significantly higher in patients with than in those without a history of HCC, and the regression of LS in patients with HCC recurrence was lower. (Figure 4) Previous HCC treatments in the present study were limited to RFA and hepatic resection because of curative therapy (Figure 2), and recurrent HCC tumors were distinct from previous tumors. High recurrence rates may be due to fibrosis in the liver being more advanced in patients with than in those without a history of HCC.
On the other hand, LS values did not correlate with HCC occurrence in the present study. Therefore, fibrosis in the liver may have been less advanced in patients without than in those with a history of HCC; however, one patient (* in Figure 4(a)) had a history of variceal bleeding. Indeed, a previous study on liver cirrhosis demonstrated that patients with grade 2 - 3 esophageal varices had higher mean LS values than those without varices or with grade 1 varices (45 versus 26 kPa) [27]. The other patient (** in Figure 4(a)) had a history of heart failure after DAA therapy. LS values were previously reported to be high in patients with elevated central venous pressure [28]. Thus, it is not impossible to estimate the association between LS values and the initial occurrence of HCC in patients with portal and venous hypertension. Although LS values did not correlate with HCC occurrence, a relationship was observed for age and AFP at SVR24. An older age, male gender, severe fibrosis, and AFP were identified as risk factors after SVR by IFN-based therapy in patients without the treatment of HCC [10] - [17]. AFP was recently identified as a risk factor after SVR by DAA therapy [29]. Predictive factors differed between HCC occurrence and recurrence after SVR by DAA in patients with HCV.
This study has several limitations. Since the numbers of patients who developed HCC without a previous history of HCC and those with a previous a history of HCC were small, we were unable to perform a multivariate analysis to identify the factors associated with HCC occurrence and recurrence in a logistic regression analysis. Furthermore, the observation period was only 33.4 months. HCC occurrence after achieving SVR on IFN-based therapy was previously reported to be less than 2.0% within three years [30]. Therefore, a longer follow-up is needed.
5. Conclusion
In conclusion, predictive factors differed between HCC occurrence and recurrence after SVR by DAA in patients with HCV. The high recurrence rate was attributed to fibrosis in the liver being more advanced in patients with than in those without a history of HCC. Age and AFP at SVR24 are predictive factors of HCC occurrence and LS48 of HCC recurrence.
Acknowledgements
The authors would like to thank Mr. Norio Sugimoto at Sugimoto Data Analysis Service for his excellent advice on data analyses.
Ethics Approval and Consent to Participate
The present study was approved by the Ethics Committee of the National Hospital Organization Nagoya Medical Center in accordance with the Helsinki Declaration. Informed consent was obtained from all individual participants included in this study.
Availability of Data and Material
Our data are available at the National Hospital Organization Nagoya Medical Center.
Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this paper.
Authors’ Contributions
All authors contributed to the conception, writing, and checking of this manuscript.
Cite this paper
Hirashima, N., Shimada, M., Urata, N., Tsunekawa, T., Unita, S., Kondo, T., Tanaka, D., Kondo, H., Saito, M. and Iwase, H. (2020) Predictive Factors Differ between Hepatocellular Carcinoma Occurrence and Recurrence after Sustained Virological Responses by Direct-Acting Antivirals in Patients with Hepatitis C. Open Journal of Gastroenterology, 10, 1-13. https://doi.org/10.4236/ojgas.2019.101001
ReferencesLawitz, E., Gane, E., Pearlman, B., Tam, E., Ghesquiere, W., Guyader, D., Alric, L., et al. (2015) Efficacy and Safety of 12 Weeks versus 18 Weeks of Treatment with Grazoprevir (MK-5172) and Elbasvir (MK-8742) with or without Ribavirin for HCV Virus Genotype 1 Infection in Previously Untreated Patients with Cirrhosis and Patients with Previous Null Response with or without Cirrhosis (C-WORTHY): A Randomized, Open-Label Phase 2 Trial. The Lancet, 385, 1075-1086.https://doi.org/10.1016/S0140-6736(14)61795-5Afdhal, N., Reddy, K.R., Nelson, D.R., Lawitz, E., Gordon, S.C., Schiff, E., Nahass, R., et al. (2014) Ledipasvir and Sofosbuvir for Previously Treated HCV Genotype 1 Infection. The New England Journal of Medicine, 370, 1483-1493. https://doi.org/10.1056/NEJMoa1316366Kumada, H., Suzuki, Y., Ikeda, K., Toyota, J., Karino, Y., Chayama, K., Kawakami, Y., et al. (2014) Daclatasvir plus Asunaprevir for Chronic HCV Genotype 1b Infection. Hepatology, 59, 2083-2091.Chayama, K., Notsumata, K., Kurosaki, M., et al. (2015) Randomized Trial of Interferon- and Ribavirin-Free Ombitasvir/Paritaprevir/Ritonavir in Treatment-Experienced Hepatitis c Virus-Infected Patients. Hepatology, 61, 1523-1532.Zeuzem, S., Dusheiko, G.M., Salupere, R., et al. (2014) Sofosbuvir and Ribavirin in HCV Genotype 2 and 3. The New England Journal of Medicine, 370, 1993-2001.https://doi.org/10.1056/NEJMoa1316145Waziry, R., Hajarizadeh, B., Grebly, J., et al. (2017) Hepatocellular Carcinoma Risk Following Direct-Acting Antiviral HCV Therapy: A Systematic Review, Meta-Analysis, and Meta-Regression. Journal of Hepatology, 67, 1204-1212.https://doi.org/10.1016/j.jhep.2017.07.025Ioannou, G.N., Green, P.K. and Berry, K. (2017) HCV Eradication Induced by Direct-Acting Antiviral Agents Reduces the Risk of Hepatocellular Carcinoma. Journal of Hepatology, 68, 25-32. https://doi.org/10.1016/j.jhep.2017.08.030Nagata, H., Nakagawa, M., Asahina, Y., et al. (2017) Effect of Interferon-Based and -Free Therapy on Early Occurrence and Recurrence of Hepatocellular Carcinoma in Chronic Hepatitis C. Journal of Hepatology, 67, 933-939. https://doi.org/10.1016/j.jhep.2017.05.028Reig, M., Marino, Z., Perello, C., et al. (2016) Unexpected High Rate of Early Tumor Recurrence in Patients with HCV-Related HCC Undergoing Interferon-Free Therapy. Journal of Hepatology, 65, 719-726. https://doi.org/10.1016/j.jhep.2016.04.008Makiyama, A., Itoh, Y., Kasahara, A., Imai, Y., Kawata, S., Yoshioka, K., et al. (2004) Characteristics of Patients with Chronic Hepatitis C Who Develop Hepatocellular Carcinoma after a Sustained Response to Interferon Therapy. Cancer, 101, 1616-1622.Chang, K.C., Hung, C.H., Lu, S.N., Wang, J.H., Lee, C.M., Chen, C.H., et al. (2012) A Novel Predictive Score for Hepatocellular Carcinoma Development in Patients with Chronic Hepatitis C after Sustained Response to Pegylated Interferon and Ribavirin Combination Therapy. Journal of Antimicrobial Chemotherapy, 67, 2766- 2772. https://doi.org/10.1093/jac/dks269Sato, A., Sata, M., Ikeda, K., Kumada, T., Izumi, N., Asahina, Y., et al. (2013) Clinical Characteristics of Patients Who Developed Hepatocellular Carcinoma after Hepatitis C Virus Eradication with Interferon Therapy: Current Status in Japan. Internal Medicine, 52, 2701-2706.Arase, Y., Kobayashi, M., Suzuki, F., Suzuki, Y., Kawamura, Y., Akuta, N., et al. (2013) Effect of Type 2 Diabetes on Risk for Malignancies Includes Hepatocellular Carcinoma in Chronic Hepatitis C. Hepatology, 57, 964-973.El-Serag, H.B., Kanwal, F., Richardson, P. and Kramer, J. (2016) Risk of Hepatocellular Carcinoma after Sustained Virological Response in Veterans with Hepatitis C Virus Infection. Hepatology, 64, 130-137.Ogawa, E., Furusyo, N., Kajiwara, E., Takahashi, K., Nomura, H., Maruyama, T., et al. (2013) Efficacy of Pegylated Interferon Alpha-2b and Ribavirin Treatment on the Risk of Hepatocellular Carcinoma in Patients with Chronic Hepatitis C: A Prospective, Multicenter Study. Journal of Hepatology, 58, 495-501. https://doi.org/10.1016/j.jhep.2012.10.017Asahina, Y., Tsuchiya, K., Nishimura, T., Muraoka, M., Suzuki, Y., Tamaki, N., et al. (2013) Alpha-Fetoprotein Levels after Interferon Therapy and Risk of Hepatocarcinogenesis in Chronic Hepatitis C. Hepatology, 58, 1253-1262.Oze, T., Hiramatsu, N., Yakushijin, T., Miyazaki, M., Yamada, A., Oshita, M., et al. (2014) Post-Treatment Levels of Alpha-Fetoprotein Predict Incidence of Hepatocellular Carcinoma after Interferon Therapy. Clinical Gastroenterology and Hepatology, 12, 1186-1195. https://doi.org/10.1016/j.cgh.2013.11.033Ikeda, K., Kawamura, Y., Kobayashi, M., et al. (2017) Direct-Acting Antivirals Dcraseed Tumor Recurrence after Initial Treatment of Hepatitis C Virus-Related Hepatocellular Carcinoma. Digestive Diseases and Sciences, 62, 2932-2942.https://doi.org/10.1007/s10620-017-4739-zYasui, Y., Kurosaki, M., Komiyama, Y., Takada, H., Tamaki, N., Watakabe, K., et al. (2018) Wisteria Floribunda Agglutinin-Positive Mac-2 Binding Protein Predicts Early Occurrence of Hepatocellular Carcinoma after SVR by Direct Acting Antivirals for HCV. Hepatology Research, 48, 1131-1139.Iio, E., Matsuura, K., Shimada, N., et al. (2019) TLL1 Variant Associated with Development of Hepatocellular Carcinoma after Eradication of Hepatitis C Virus by Interferon-Free Therapy. Journal of Gastroenterology, 54, 339-346.https://doi.org/10.1007/s00535-018-1526-3Merchante, N., Rivero-Juárez, A., Téllez, F., et al. (2012) Liver Stiffness Predicts Outcome in Human Immunodeficiency Virus/Hepatitis C Virus-Coinfected Patients with Compensated Cirrhosis. Hepatology, 56, 228-238.Durango, E., Dietrich, C., Seitz, H.K., et al. (2013) Direct Comparison of the FibroScan XL and M Probes for Assessment of Liver Fibrosis in Obese and Nonobese Patients. Hepatic Medicine, 5, 43-52. https://doi.org/10.2147/HMER.S45234Nakamura, A., Kaneko, N., Villemagne, V.L., et al. (2018) High Performance Plasma Amyloid-β Biomarkers for Alzheimer’s Disease. Nature, 554, 249-254.Masias, J., Rivero, A., Cifucentes, C., et al. (2013) Sustained Viral Response to Pegylated Interferon Plus Ribavirin Leads to Normalization of Liver Stiffness in Hepatitis C Virus-Infected Patients. Enfermedades Infecciosas y Microbiología Clínica, 31, 424-429. https://doi.org/10.1016/j.eimc.2012.12.004Bachofner, J.A., Valli, P.V., Kroger, A., et al. (2017) Direct Antiviral Agent Treatment of Chronic Hepatitis C Results in Rapid Regression of Transient Elastography and Fibrosis Markers Fibrosis-4 Score and Aspartate Aminotransferase-Platelet Ratio Index. Liver International, 37, 369-376.Martini, S., Sacco, M., Strona, S., et al. (2017) Impact of Viral Eradication with Sofosbuvir-Based Therapy on the Outcome of Post-Transplant Hepatitis C with Severe Fibrosis. Liver International, 37, 62-70.Sporea, I., Ratiu, L., Sirli, R., Popescu, A. and Bota, S. (2011) Value of Transient Elastography for the Prediction of Variceal Bleeding. World Journal of Gastroenterology, 17, 2206-2210. https://doi.org/10.3748/wjg.v17.i17.2206Sandin, L., Fourquet, B., Hasquenoph, L.M., et al. (2003) Transient Elastography: A New Noninvasive Method for Assessment of Hepatic Fibrosis. Ultrasound in Medicine and Biology, 29, 1705-1713. https://doi.org/10.1016/j.ultrasmedbio.2003.07.001Watanabe, T., Tokumoto, Y., Joko, K., et al. (2019) Predictors of Hepatocellular Carcinoma Occurrence after Direct-Acting Antiviral Therapy in Patients with Hepatitis C Virus Infection. Hepatology Research, 49, 136-146.Hiramatsu, N., Oze, T. and Takehara, T. (2014) Suppression of Hepatocellular Carcinoma Development in Hepatitis C Patients Given Interferon-Based Antiviral Therapy. Hepatology Research, 45, 152-161.