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Dive into the research topics where Kenneth S. H. Chok is active.

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Featured researches published by Kenneth S. H. Chok.


Gastroenterology | 2011

Entecavir monotherapy is effective in suppressing hepatitis B virus after liver transplantation.

James Fung; Cindy K. Cheung; See Ching Chan; Man-Fung Yuen; Kenneth S. H. Chok; William W. Sharr; Wing Chiu Dai; Albert C. Y. Chan; Tan To Cheung; Simon Hy Tsang; Banny K. Lam; Ching-Lung Lai; Chung Mau Lo

BACKGROUND & AIMS We investigated the efficacy of entecavir, a cyclopentyl guanosine nucleoside analogue, as monoprophylaxis in patients with chronic hepatitis B who received a liver transplant. METHODS We studied data from 80 consecutive patients who received a liver transplant (47 from living donors and 33 from deceased donors) for hepatitis B-related disease and entecavir monotherapy as prophylaxis. None of the patients received hepatitis B immunoglobulin. Indications for transplant included decompensation from cirrhosis (27.5%), acute-on-chronic hepatitis B (47.5%), and hepatocellular carcinoma (25%). The median follow-up time was 26 months (range, 5-40 months). Before transplant, 33 patients were not on antiviral therapy and 47 were on oral therapy (18 had received less than 3 months of treatment). RESULTS At the time of transplant, the median log HBV DNA level was 3.5 copies/mL (range, 1.54-8.81); 21 patients (26%) had undetectable levels of HBV DNA. The cumulative rate of hepatitis B surface antigen (HBsAg) loss was 86% and 91% after 1 and 2 years, respectively. Ten patients had reappearance of HBsAg. Eighteen patients (22.5%) were HBsAg positive at the time of their last examination; 17 of these had undetectable levels of HBV DNA, and the remaining patient had a low level of HBV DNA (217 copies/mL). There was no evidence of mutations at sites that confer resistance to entecavir among patients who were HBsAg positive. CONCLUSIONS Although only 26% of patients had complete viral suppression at the time of transplant, 91% lost HBsAg, with 98.8% achieving undetectable levels of HBV DNA. A hepatitis B immunoglobulin-free regimen of entecavir monotherapy is effective after liver transplantation for chronic hepatitis B.


Annals of Surgery | 2013

Long-term survival analysis of pure laparoscopic versus open hepatectomy for hepatocellular carcinoma in patients with cirrhosis: A single-center experience

Tan To Cheung; Ronnie Tung-Ping Poon; Wai Key Yuen; Kenneth S. H. Chok; Caroline R. Jenkins; See Ching Chan; Sheung Tat Fan; Chung Mau Lo

Introduction: Laparoscopic liver resection has been reported as a safe and effective approach to the management of liver cancer. However, studies of long-term outcomes regarding tumor recurrence and patient survival in comparison with the conventional open approach are limited. The aim of this study was to analyze the survival outcome of laparoscopic liver resection versus open liver resection. Patients and Methods: Between October 2002 and September 2009, 32 patients underwent pure laparoscopic liver resection for hepatocellular carcinoma (HCC). Case-matched control patients (n = 64) who received open liver resection for HCC were included for comparison. Patients were matched in terms of cancer stage, tumor size, location of tumor, and magnitude of resection. Immediate operation outcomes, operation morbidity, disease-free survival, and overall survival were compared between groups. Results: With the laparoscopic group compared with the open resection group, operation time was 232.5 minutes versus 204.5 minutes (P = 0.938), blood loss was 150 mL versus 300 mL (P = 0.001), hospital stay was 4 days versus 7 days (P < 0.0001), postoperative complication was 2 (6.3%) versus 12 (18.8%) (P = 0.184), disease-free survival was 78.5 months versus 29 months (P = 0.086), and overall survival was 92 months versus 71 months (P = 0.142). The disease-free survival for stage II HCC was 22.1 months versus 12.4 months (P = 0.075). Conclusions: Laparoscopic liver resection for HCC is associated with less blood loss, shorter hospital stay, and fewer postoperative complications in selected patients with no compromise in survival.


Journal of The American College of Surgeons | 2008

Risk factors and prognostic factors of local recurrence after radiofrequency ablation of hepatocellular carcinoma.

Vincent W. T. Lam; Kelvin K. Ng; Kenneth S. H. Chok; Tt Cheung; Jimmy Yuen; Helen Tung; Wk Tso; Sheung Tat Fan; Ronnie Tung-Ping Poon

BACKGROUND Local recurrence rates after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) vary from 2% to 36% in the literature. Limited data were available about the prognostic significance of local recurrence. STUDY DESIGN Between April 2001 and March 2006, 273 patients with 357 hepatocellular carcinoma nodules underwent RFA, with radiologically complete tumor ablation after a single session of RFA. The risk factors of local recurrence and its impact on overall survival of patients were analyzed. RESULTS With a median followup period of 24 months, local recurrence occurred in 35 patients (12.8%). By multivariate analysis, tumor size > 2.5 cm was the only independent risk factor for local recurrence. There was no notable difference in overall survival between patients with and without local recurrence. By multivariate analysis, local recurrence more than 12 months after RFA and complete response after additional treatment of local recurrence were associated with better overall survival in patients with local recurrence. CONCLUSIONS This study demonstrated that tumor size > 2.5 cm was the main risk factor for local recurrence after RFA of hepatocellular carcinoma. Our data suggested that additional aggressive treatment of local recurrence aimed at complete tumor response improves overall survival of patients. Late local recurrence was also associated with better prognosis, suggesting different tumor biology between early and late local recurrent tumors after RFA.


British Journal of Surgery | 2009

Impact of postoperative complications on long-term outcome of curative resection for hepatocellular carcinoma

Kenneth S. H. Chok; Kelvin Kc. Ng; Rtp Poon; Cm Lo; St Fan

The aim of this retrospective study was to determine the impact of postoperative complications on the long‐term outcome of curative liver resection for hepatocellular carcinoma (HCC).


Archives of Surgery | 2011

Impact of Antiviral Therapy on the Survival of Patients After Major Hepatectomy for Hepatitis B Virus–Related Hepatocellular Carcinoma

Albert C. Y. Chan; Kenneth S. H. Chok; Wai Key Yuen; See Ching Chan; Ronnie Tung-Ping Poon; Chung Mau Lo; Sheung Tat Fan

OBJECTIVES To assess whether commencement of antiviral therapy after hepatectomy improves the prognosis of hepatocellular carcinoma (HCC) in preoperatively antiviral-naive patients with chronic hepatitis B virus (HBV) infection. DESIGN Retrospective analysis of a prospectively collected database. SETTING University teaching hospital. MAIN OUTCOME MEASURES Disease-free and overall survival rates. RESULTS One hundred thirty-six patients received major hepatectomy for HBV-related HCC from September 1, 2003, through December 31, 2007. Among them, 42 patients received antiviral therapy (treatment group) after hepatectomy, whereas 94 did not (control group). Patient demographics, preoperative liver function, tumor characteristics, and liver function at the time of tumor recurrence were comparable between the 2 groups. Disease-free and overall survival rates were significantly prolonged in the treatment group. The 1-, 3-, and 5-year overall survival rates in the treatment group were 88.1%, 79.1%, and 71.2%, respectively; in the control group, 76.5%, 47.5%, and 43.5%, respectively (P = .005). The 1-, 3-, and 5-year disease-free survival rates in the treatment group were 66.5%, 51.4%, and 51.4%, respectively; in the control group, 48.9%, 33.8%, and 33.8%, respectively (P = .05). Subgroup analysis stratified against tumor stage and major vascular invasion showed that posthepatectomy antiviral treatment conferred a significant survival benefit in stages I and II tumors or HCCs without major venous invasion. CONCLUSIONS Antiviral therapy improves the prognosis of HBV-related HCC. It should be considered after hepatectomy for HBV-related HCC, especially in early-stage tumors.


The American Journal of Gastroenterology | 2013

Oral Nucleoside/Nucleotide Analogs Without Hepatitis B Immune Globulin After Liver Transplantation for Hepatitis B

James Fung; Sc Chan; Cindy K. Cheung; Man-Fung Yuen; Kenneth S. H. Chok; William W. Sharr; Albert C. Y. Chan; Tt Cheung; Wai-Kay Seto; Sheung Tat Fan; Ching-Lung Lai; Chung Mau Lo

OBJECTIVES:The long-term outcomes of oral antiviral therapy without hepatitis B immune globulin (HBIG) in prevention of reinfection with hepatitis B after liver transplantation are not known. We aimed to determine the long-term outcomes from a large population of chronic hepatitis B (CHB) liver transplant recipients using oral antiviral therapy alone.METHODS:A total of 362 consecutive CHB patients transplanted from January 2003 to May 2011 were included. None of the patients received HBIG. Viral serology, viral load, and liver biochemistry were performed at regular intervals during follow-up.RESULTS:Of the 362 patients, 176 (49%), 142 (39%), and 44 (12%) were on lamivudine (LAM), entecavir (ETV), and combination therapy (predominantly LAM+adefovir), respectively, at the time of transplant. The median follow-up length was 53 months. The rate of hepatitis B surface antigen seronegativity and hepatitis B virus (HBV) DNA suppression to undetectable levels at 8 years was 88 and 98%, respectively. The virological relapse rates (>1 log increase IU/ml) at 1, 3, 5, and 8 years was 5, 10, 13 and 16%, respectively. The virological relapse rate at 3 years for LAM, ETV, and combination group was 17, 0, and 7%, respectively (P<0.001). Forty-two patients had virological relapse, of which 36 had YMDD mutation (31 in the LAM group and 5 in the combination group). The overall 8-year survival was 83%, with no difference between the three treatment groups (P=0.94). No mortality from HBV recurrence occurred in the 362 patients.CONCLUSIONS:Oral nucleoside/nucleotide analogs without HBIG are effective in preventing graft loss secondary to hepatitis B recurrence after liver transplantation. However, new agents with a high barrier to resistance should be used to minimize drug resistance and to prevent virological rebound.


Annals of Surgery | 2011

High-Intensity Focused Ultrasound for Hepatocellular Carcinoma A Single-Center Experience

Kelvin K. Ng; Ronnie Tung-Ping Poon; See Ching Chan; Kenneth S. H. Chok; Tan To Cheung; Helen Tung; Ferdinand S. K. Chu; Wai Kuen Tso; Wan Ching Yu; Chung Mau Lo; Sheung Tat Fan

Objective: This study aims to evaluate the outcome of patients with hepatocellular carcinoma (HCC) treated by high-intensity focused ultrasound (HIFU) in a single tertiary referral center. Background: HIFU is the latest developed local ablation technique for unresectable HCC. The initial experience on its efficacy is promising, but the survival benefit of patients undergoing HIFU for HCC is poorly defined. Methods: From October 2006 to December 2008, 49 patients received HIFU for unresectable HCC. Each patient underwent a single session of HIFU with a curative intent. Treatment efficacy and survival outcome were evaluated. Clinicopathologic factors affecting the primary technique effectiveness and overall survival rates were investigated by univariate analysis. Results: The median size of the treated tumors was 2.2 cm, ranging from 0.9 to 8 cm. The majority of patients had single tumors (n = 41, 83.6%). Thirty-one patients (63.2%) had artificial right pleural effusion during HIFU treatment to reduce damage to the lung and diaphragm. The hospital mortality rate was 2% (n = 1) and the complication rate was 8.1% (n = 4). The primary technique effectiveness rate was 79.5% (39 of 49 patients). It increased from 66.6% in the initial series to 89.2% in the last 28 patients. Tumor size (≥3.0 cm) was the significant risk factor affecting the complete ablation rate. The 1- and 3-year overall survival rates were 87.7% and 62.4%, respectively. Child-Pugh liver function grading was the significant prognostic factor influencing the overall survival rate. Conclusions: HIFU is an effective treatment modality for unresectable HCC with a high technique effectiveness rate and favorable survival outcome.


The Journal of Nuclear Medicine | 2013

11C-Acetate and 18F-FDG PET/CT for Clinical Staging and Selection of Patients with Hepatocellular Carcinoma for Liver Transplantation on the Basis of Milan Criteria: Surgeon’s Perspective

Tan To Cheung; Chi Lai Ho; Chung Mau Lo; Sirong Chen; See Ching Chan; Kenneth S. H. Chok; James Y. Y. Fung; Albert C. Y. Chan; William W. Sharr; Thomas Yau; Ronnie T.P. Poon; Sheung Tat Fan

The success of liver transplantation (LT) for hepatocellular carcinoma (HCC) is enhanced by careful patient selection on the basis of the Milan criteria. The criteria are traditionally assessed by contrast CT, which is known to be affected by structural or architectural changes in cirrhotic livers. We aimed to compare dual-tracer (11C-acetate and 18F-FDG) PET/CT with contrast CT for patient selection on the basis of the Milan criteria. Methods: Patients who had HCC and had undergone both preoperative dual-tracer PET/CT and contrast CT within a 1-mo interval were retrospectively studied. They then underwent either LT (n = 22) or partial hepatectomy (PH) (n = 21; HCC of ≤ 8 cm). Imaging data were compared with data from postoperative pathologic analysis for accuracy in assessment of parameters specified by the Milan criteria (tumor size and extent, vascular invasion, and metastasis), TNM staging, and patient selection for LT. Results: Dual-tracer PET/CT performed equally well in both LT and PH groups for HCC detection (94.1% vs. 95.8%) and TNM staging (90.9% vs. 90.5%). Contrast CT performed reasonably well in the LT group but not in the PH group for HCC detection (67.6% vs. 37.5%) and TNM staging (54.5% vs. 28.6%). In the LT group, the sensitivity and specificity of contrast CT for patient selection on the basis of the Milan criteria were 43.8% and 66.7%, respectively (comparable to values in the literature); the sensitivity and specificity of dual-tracer PET/CT were 93.8% and 100%, respectively (both Ps < 0.05). From the surgeon’s perspective, we tended to perform transplantation for patients with higher diagnostic certainty (stricter CT criteria) because of a shortage of donor grafts. Patients who were not transplant candidates usually underwent up-front hepatectomy without the benefit of reassessment contrast CT, resulting in lower accuracies for the PH group. The overall sensitivity (96.8%) and specificity (91.7%) of dual-tracer PET/CT for patient selection for LT were significantly higher than those of contrast CT (41.9% and 33.0%, respectively) (both Ps < 0.05). Sources of error for contrast CT were related to cirrhosis or previous treatment and included difficulty in differentiating cirrhotic nodules from HCC (39%) and estimation of tumor size (14%). Overstaging of vascular invasion (4.6%) and extrahepatic metastases (4.6%) was infrequent. The rate of false-negative results of dual-tracer PET/CT was 4.7%. Conclusion: Dual-tracer PET/CT was significantly less affected by cirrhotic changes than contrast CT for HCC staging and patient selection for LT on the basis of the Milan criteria. The inclusion of dual-tracer PET/CT in pretransplant workup may warrant serious consideration.


Liver Transplantation | 2013

Treatment strategy for recurrent hepatocellular carcinoma: salvage transplantation, repeated resection or radiofrequency ablation?

Albert C. Y. Chan; See Ching Chan; Kenneth S. H. Chok; Tan To Cheung; Dai Wing Chiu; Ronnie Tung-Ping Poon; Sheung Tat Fan; Chung Mau Lo

The objective of this study was to evaluate the efficacy of salvage liver transplantation (SLT), repeated hepatic resection (RR), and repeated radiofrequency ablation (rRFA) for patients with postoperative tumor recurrence. The optimal treatment strategy for patients with recurrent hepatocellular carcinoma (HCC) remains unclear. From January 1993 to September 2009, 532 patients underwent either hepatic resection or radiofrequency ablation (RFA) for HCC within the Milan criteria. In all, 219 patients experienced intrahepatic recurrence, and 87 were selected for SLT (n=19), RR (n=24), or rRFA (n=44). Their clinicopathological data were reviewed, and their survival outcomes were assessed with Kaplan‐Meier methods. Seventy‐four of 220 patients (33.6%) developed recurrent HCC within the Milan criteria. The median Model for End‐Stage Liver Disease (MELD) scores for SLT, RR, and rRFA were 10.7, 7.2, and 8.3, respectively (P<0.001). The 1‐, 3‐, and 5‐year tumor‐free survival rates were 68.4%, 57.9%, and 57.9%, respectively, for SLT; 69.7%, 49.3%, and 49.3%, respectively, for RR; and 40.0%, 19.8%, and 10.6%, respectively, for rRFA (P=0.001). For recurrent HCC within the Milan criteria, the 1‐, 3‐, and 5‐year tumor‐free survival rates for SLT were all 60%; the corresponding rates were 70.2%, 48.0%, and 48.0% for RR and 41.0%, 20.3%, and 10.9% for RFA (P=0.004). After adjustments of the MELD score, the 5‐year survival rates for SLT, RR, and rRFA were 50.0%, 48.0%, and 11.4%, respectively (P=0.003). A subgroup analysis showed that SLT and RR led to comparable survival outcomes, but both treatments led to significantly better survival outcomes than rRFA (P<0.001). In conclusion, SLT is an efficacious treatment for patients with recurrent HCC and should be considered when RR is not feasible. Liver Transpl 19:411–419, 2013.


Liver Transplantation | 2011

Can positron emission tomography with the dual tracers [11C]acetate and [18F]fludeoxyglucose predict microvascular invasion in hepatocellular carcinoma?

Tan To Cheung; See Ching Chan; Chi Lai Ho; Kenneth S. H. Chok; Albert C. Y. Chan; William W. Sharr; Kelvin K. Ng; Ronnie Tung-Ping Poon; Chung Mau Lo; Sheung Tat Fan

Microvascular invasion is a poor prognostic indicator of the recurrence of hepatocellular carcinoma (HCC) after surgical treatment. Positron emission tomography (PET) with [18F]fludeoxyglucose ([18F]FDG) as a tracer has been employed to predict the prognosis before surgery for various kinds of tumors, but it has not been found to be sensitive enough for HCC. Thus, [11C]acetate has been adopted as an additional tracer. This study was designed to evaluate the ability of dual‐tracer PET ([18F]FDG and [11C]acetate) to predict microvascular invasion before liver resection or transplantation. Fifty‐eight HCC patients who were preoperatively examined with whole‐body dual‐tracer PET were studied. Twenty‐five patients were [18F]FDG‐positive, and 56 were [11C]acetate‐positive. The sensitivity of [18F]FDG in detecting primary HCC was 43%, and the sensitivity of [11C]acetate was 93%. Twenty‐nine patients had HCC with microvascular invasion according to the final pathological examination. The sensitivity, specificity, positive predictive value, and negative predictive value of [18F]FDG PET in predicting microvascular invasion were 55.2%, 69%, 64%, and 60.6%, respectively; the corresponding rates for [11C]acetate PET were 93.1%, 0%, 48.2%, and 0%. The factors associated with HCC recurrence, which included multifocal involvement, a large tumor size, microsatellite lesions, poor HCC differentiation, and an advanced stage of disease, were analyzed and compared with positive PET results. A tumor size greater than 5 cm was significantly associated with positive [18F]FDG PET results; [11C]acetate was not associated with poor prognostic indicators. Preoperative [18F]FDG PET may predict microvascular invasion. The addition of [11C]acetate improves the overall sensitivity of PET, but it has no incremental value in predicting microvascular invasion. Liver Transpl 17:1218–1225, 2011.

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Chung Mau Lo

University of Hong Kong

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Kelvin K. Ng

University of Hong Kong

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