Early Prediction of Post-hepatectomy Liver Failure in Patients Undergoing Major Hepatectomy Using a PHLF Prognostic Nomogram

BACKGROUND

Liver resection (LR) is the main modality of treatment for hepatocellular carcinoma (HCC) and colorectal liver metastasis (CRLM). Post-hepatectomy liver failure (PHLF) remains the most dreaded complication. We aim to create a prognostic score for early risk stratification of patients undergoing LR.

METHODOLOGY

Clinical and operative data of 472 patients between 2000 and 2016 with HCC or CRLM undergoing major hepatectomy were extracted and analysed from a prospectively maintained database. PHLF was defined using the 50-50 criteria.

RESULTS

Liver cirrhosis and fatty liver were histologically confirmed in 35.6% and 53% of patients. 4.7% (n = 22) of patients had PHLF. A 90-day mortality was 5.1% (n = 24). Pre-operative albumin-bilirubin score (p = 0.0385), prothrombin time (p < 0.0001) and the natural logarithm of the ratio of post-operative day 1 to pre-operative serum bilirubin (SB) (ln(_POD1Bil/_pre-opBil); p < 0.0001) were significantly independent predictors of PHLF. The PHLF prognostic nomogram was developed using these factors with receiver operating curve showing area under curve of 0.88. Excellent sensitivity (94.7%) and specificity (95.7%) for the prediction of PHLF (50-50 criteria) were achieved at cut-offs of 9 and 11 points on this model. This score was also predictive of PHLF according to _PeakBil > 7 and International Study Group for Liver Surgery criteria, intensive care unit admissions, length of stay, all complications, major complications, re-admissions and mortality (p < 0.05).

CONCLUSIONS

The PHLF nomogram ( https://tinyurl.com/SGH-PHLF-Risk-Calculator ) can serve as a useful tool for early identification of patients at high risk of PHLF before the 'point of no return'. This allows enforcement of closer monitoring, timely intervention and mitigation of adverse outcomes.

Pre-operative Imaging Characteristics in Histology-Proven Resected Intrahepatic Cholangiocarcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are the most common primary liver cancers. With the increasing incidence of ICC over the past two decades in Asia, it is essential to differentiate between HCC and ICC. However, ICC may mimic the radiological appearance of HCC on computed tomography scans (CT) and magnetic resonance imaging (MRI), leading to misdiagnosis of ICC. The objective of this study is to evaluate and describe the association of specific pre-operative imaging characteristics (arterial enhancement, portal venous washout) in patients with histologically proven resected ICC in our centre.

METHODS

Data on patients with histology-proven ICC and mixed hepatocellular-cholangiocarcinomas (HCC-CC) who had undergone surgical resection at Singapore General Hospital (SGH) were identified from a prospectively maintained database. Pre-operative cross-sectional imaging reports were analysed.

RESULTS

Ninety-one patients underwent resection between 1 January 2000 and 31 December 2016. Among those with no risk factors for HCC, a significant percentage of patients with ICC (24.3%) show imaging characteristics of both arterial phase hyperenhancement and non-peripheral venous washout. Among patients with risk factors for HCC, between 20.0 and 33.3% of patients with pure ICC fulfilled the imaging criteria for HCC, and this proportion was generally even higher in the mixed HCC-CC group.

CONCLUSIONS

A significant proportion of patients with pure ICC showed pre-operative imaging characteristics which fulfilled the diagnostic criteria for HCC. The differential of ICC should be borne in mind in populations where both malignancies are endemic.

A phase II open-label, single-center, nonrandomized trial of Y90-radioembolization in combination with nivolumab in Asian patients with advanced hepatocellular carcinoma: CA 209-678

4590

Background: Nivolumab (N) and Y90-radioembolization (RE) are both therapeutic options in advanced hepatocellular carcinoma (aHCC). Increasing evidence suggests that radiotherapy synergizes with immune checkpoint inhibitors to augment anti-tumour effects. Methods: Eligible Child-Pugh A aHCC patients (pts) were treated with Y90-RE followed by N 240mg, 21 days after Y90-RE and every 2 weeks thereafter. Pre- and on-treatment tumor biopsies together with circulating biomarkers were obtained. Primary end-point was overall response rate (ORR) (per RECIST v 1.1). Overall response was defined as the composite overall response observed for the lesions within Y90-RE field and outside Y90-RE field. Key secondary end points included disease control rate (DCR), progression free survival (PFS), overall survival (OS), and safety. 36 evaluable pts were needed to assess whether the addition of N improved the ORR of Y90-RE from 21% to 41% as determined by Simon two-stage optimal design with 80% power and one sided significance level of 0.05. Results: Forty pts were enrolled of which 36 were evaluable. At baseline: 63.9% were HepB in aetiology; 63.9% BCLC stage C; 47.2% had AFP > 400ng/mL; number of liver lesions – median 5 (range 1- 20); size of largest liver lesion – median 80mm (range 14-177mm); 27.8% had prior TACE; and 13.9% had prior systemic therapy. ORR was 31% (95% CI 16.4 - 48.1%). Eight out of 11 responders had not progressed at study cut-off. DCR was 58.3%. 81% of target lesions within Y90-RE field regressed. With a median follow up of 16.4 months, median PFS and OS were 4.6 months (95% CI 2.3m - 8.4m) and 15.1 months (95% CI 7.8m - NE) respectively. Six- and 12-month PFS rates were 44.2% (95% CI 27.3% - 59.9%) and 26.1% (95% CI 11.2% - 43.8%) respectively. Overall, N+ Y90-RE was well tolerated and safe; only 11% had grade 3/4 treatment related adverse events (AEs). Responders demonstrated significant alterations of LIF, MIG and Eotaxin3 levels in the pre-treatment cytokine analyses. Conclusions: Combination N+Y90-RE resulted in an encouraging ORR of 31% (95% CI 16.4 - 48.1%) in aHCC. 81% of target lesions within Y90-RE field regressed suggesting synergy in combining Y90-RE with nivolumab. This combination is safe and tolerable with low G3/4 treatment related AEs of 11%. Further biomarker analyses will be presented at the meeting. Clinical trial information: NCT03033446 .

Novel method of intraoperative liver tumour localisation with indocyanine green and near-infrared imaging

INTRODUCTION

Fluorescence imaging (FI) with indocyanine green (ICG) is increasingly implemented as an intraoperative navigation tool in hepatobiliary surgery to identify hepatic tumours. This is useful in minimally invasive hepatectomy, where gross inspection and palpation are limited. This study aimed to evaluate the feasibility, safety and optimal timing of using ICG for tumour localisation in patients undergoing hepatic resection.

METHODS

From 2015 to 2018, a prospective multicentre study was conducted to evaluate feasibility and safety of ICG in tumour localisation following preoperative administration of ICG either on Day 0-3 or Day 4-7.

RESULTS

Among 32 patients, a total of 46 lesions were resected: 23 were hepatocellular carcinomas (HCCs), 12 were colorectal liver metastases (CRLM) and 11 were benign lesions. ICG FI identified 38 (82.6%) lesions prior to resection. The majority of HCCs were homogeneous fluorescing lesions (56.6%), while CLRM were homogeneous (41.7%) or rim-enhancing (33.3%). The majority (75.0%) of the lesions not detected by ICG FI were in cirrhotic livers. Most (84.1%) of ICG-positive lesions detected were < 1 cm deep, and half of the lesions ≥ 1 cm in depth were not detected. In cirrhotic patients with malignant lesions, those given ICG on preoperative Day 0-3 and Day 4-7 had detection rates of 66.7% and 91.7%, respectively. There were no adverse events.

CONCLUSION

ICG FI is a safe and feasible method to assist tumour localisation in liver surgery. Different tumours appear to display characteristic fluorescent patterns. There may be no disadvantage of administering ICG closer to the operative date if it is more convenient, except in patients with liver cirrhosis.

Expression of CD38 on Macrophages Predicts Improved Prognosis in Hepatocellular Carcinoma

Background: CD38 is involved in the adenosine pathway, which represents one of the immunosuppressive mechanisms in cancer. CD38 is broadly expressed across immune cell subsets, including human macrophages differentiated in vitro from monocytes, but expression by tissue-resident macrophages remains to be demonstrated. Methods: Tissue samples were obtained from 66 patients with hepatocellular carcinoma (HCC) from Singapore and analyzed using immunohistochemistry. Tumor-infiltrating leukocytes (TILs) were further examined using DEPArray™, and the phenotype of freshly isolated TILs was determined using flow cytometry. Results: CD38 was frequently co-expressed with the macrophage-specific marker CD68. CD38⁺CD68⁺ macrophage density was associated with improved prognosis after surgery, while total CD68⁺ macrophage density was associated with poor prognosis. DEPArray™ analysis revealed the presence of large (>10 μm), irregularly shaped CD45⁺CD14⁺ cells that resembled macrophages, with concurrent CD38⁺ expression. Flow cytometry also revealed that majority of CD14⁺HLA-DR⁺ cells expressed CD38. Conclusion: CD38 expression was clearly demonstrated on human macrophages in an in vivo setting. The positive association identified between CD38⁺ macrophage density and prognosis may have implications for routine diagnostic work.

Outcome of minimally-invasive versus open pancreatectomies for solid pseudopapillary neoplasms of the pancreas: A 2:1 matched case-control study

Backgrounds/Aims

Solid pseudopapillary neoplasm (SPPN) is typically seen in young healthy females who would likely benefit from minimally-invasive pancreatectomy (MIP). A few comparative studies have suggested that MIP is associated with favorable outcomes when compared to the open approach for SPPN. This study aims to mitigate potential selection bias by performing a matched case-control study comparing MIP vs open pancreatectomy (OP) for SPPN.

Methods

We performed a single-institution retrospective electronic chart review of all patients who underwent surgery for pathologically confirmed SPPN between 2000 and 2017. A 2:1 matched comparison using age, gender, tumor size and the type of pancreatectomy was performed between OP and MIP.

Results

A total of 40 patients with a median age of 40.3 years (range 16.5-64.4) and female sex predominance (n=34, 85.0%) underwent surgery during the study period. Nine patients underwent MIP. Matched comparison between 18 OP and 9 MIP demonstrated that MIP was associated with a longer median operating time (305 vs 180 min, p=0.046) and shorter median postoperative stay (6 vs 9 days, p=0.015). There were no significant differences in intraoperative blood loss, blood transfusion requirements, postoperative morbidity (including postoperative pancreatic fistula) and mortality, resection margins, lymph node yield and long-term survival.

Conclusions

MIP is a safe and viable option in the management of SPPN with the benefit of a shorter postoperative length of stay at the expense of a longer operation time. There was no significant difference in oncologic outcomes between both groups of patients.

Liver Resection for Nonalcoholic Fatty Liver Disease-Associated Hepatocellular Carcinoma

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD)-related hepatocellular carcinoma (HCC) is on the rise worldwide, but data on long-term outcomes after curative operations are limited. The primary aim of this study was to characterize the perioperative and long-term outcomes after liver resection. The secondary aim was to investigate the influence of the histologic severity of nonalcoholic steatohepatitis and its impact on perioperative outcomes and long-term survival.

METHODS

A total of 996 patients who underwent liver resection for HCC in our institution were analyzed. Patients were categorized into subgroups of NAFLD vs non-NAFLD HCC based on histologic evidence of hepatic steatosis. Comparisons of patients' demographic, clinical, and surgical characteristics; postoperative complications; and survival outcomes were performed.

RESULTS

Eight hundred and forty-four patients had non-NAFLD HCC and 152 patients had NAFLD HCC. Comorbidities were significantly more common in the NAFLD group (p < 0.0001). In the non-NAFLD group, larger median tumor size, higher liver cirrhosis, and lower median neutrophil to lymphocyte ratio were observed (p < 0.0001). The NAFLD group had a greater amount of intraoperative blood loss, more postoperative complications, and longer length of stay. Five-year overall survival was significantly better in the NAFLD group (p = 0.0355). Significant factors that contribute to poorer survival outcomes include age, congestive cardiac failure, Child-Pugh's class B, cirrhosis, tumor size, multinodularity, and R1 resection. For NAFLD group, patients with abnormal parenchyma showed poorer survival and 5-year overall survival rates (64.8% vs 75.6%; p = 0.2291).

CONCLUSIONS

Nonalcoholic fatty liver disease-related HCC is associated with greater surgical morbidity and post-hepatectomy liver failure. Despite this, long-term survival outcomes are favorable compared with non-NAFLD etiologies.

Circulating microRNAs as Potential Diagnostic and Prognostic Biomarkers in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer with high mortality, due to late diagnosis and limited treatment options. Blood miRNAs, which circulate in a highly stable, cell-free form, show promise as novel potential biomarkers for early detection of HCC. Whole miRNome profiling was performed to identify deregulated miRNAs between HCC and normal healthy (NH) volunteers. These deregulated miRNAs were validated in an independent cohort of HCC, NH and chronic Hepatitis B (CHB) volunteers and finally in a 3^rd cohort comprising NH, CHB, cirrhotic and HCC volunteers to evaluate miRNA changes during disease progression. The associations between circulating miRNAs and liver-damage markers, clinicopathological characteristics and survival outcomes were analysed to identify prognostic markers. Twelve miRNAs are differentially expressed between HCC and NH individuals in all three cohorts. Five upregulated miRNAs (miR-122-5p, miR-125b-5p, miR-885-5p, miR-100-5p and miR-148a-3p) in CHB, cirrhosis and HCC patients are potential biomarkers for CHB infection, while miR-34a-5p can be a biomarker for cirrhosis. Notably, four miRNAs (miR-1972, miR-193a-5p, miR-214-3p and miR-365a-3p) can distinguish HCC from other non-HCC individuals. Six miRNAs are potential prognostic markers for overall survival.

Multidimensional analyses reveal distinct immune microenvironment in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND AND AIMS

Chronic inflammation induced by chronic hepatitis B virus (HBV) infection increases the risk of hepatocellular carcinoma (HCC). However, little is known about the immune landscape of HBV-related HCC and its influence on the design of effective cancer immunotherapeutics.

METHODS

We interrogated the immune microenvironments of HBV-related HCC and non-viral-related HCC using immunohistochemistry and cytometry by time-of-flight (CyTOF). On identifying unique immune subsets enriched in HBV-related HCC, we further interrogated their phenotypes and functions using next-generation sequencing (NGS) and in vitro T-cell proliferation assays.

RESULTS

In-depth interrogation of the immune landscapes showed that regulatory T cells (T_REG) and CD8⁺ resident memory T cells (T_RM) were enriched in HBV-related HCC, whereas Tim-3⁺CD8⁺ T cells and CD244⁺ natural killer cells were enriched in non-viral-related HCC. NGS of isolated T_REG and T_RM from HBV-related HCC and non-viral-related HCC identified distinct functional signatures associated with T-cell receptor signalling, T-cell costimulation, antigen presentation and programmed cell death protein 1 (PD-1) signalling. T_REG and T_RM from HBV-related HCC expressed more PD-1 and were functionally more suppressive and exhausted than those from non-virus-related HCC. Furthermore, immunosuppression by PD-1⁺ T_REG could be reversed with anti-PD-1 blockade. Using multiplexed tissue immunofluorescence, we further demonstrated that T_REG and T_RM contributed to overall patient survival: T_REG were associated with a poor prognosis and T_RM were associated with a good prognosis in HCC.

CONCLUSION

We have shown that the HBV-related HCC microenvironment is more immunosuppressive and exhausted than the non-viral-related HCC microenvironment. Such in-depth understanding has important implications in disease management and appropriate application of immunotherapeutics.

Rare case of gallbladder mucocele causing gastric outlet obstruction treated with cholecystectomy

INTRODUCTION

Gallstone(s) impacted at the distal small bowel causing intestinal obstruction as a result of cholecystoenteric fistula is a well-known, albeit uncommon surgical condition. The rare Bouveret's Syndrome, which refers to the proximal impaction of gallstone(s) in the duodenum or pylorus resulting in the gastric outlet obstruction (GOO), has also been described in the literature. However, gallbladder mucocele with extrinsic compression of the duodenum and/or pylorus causing GOO is a separate entity that is extremely rare.

PRESENTATION OF CASE

A patient who presented with loss of appetite and weight, with intermittent vomiting over a course of eight months was found to have GOO secondary to extrinsic duodenal compression from a large gallbladder mucocele. Surgical intervention in the form of cholecystectomy was performed, and the patient's symptoms resolved post-operatively.

DISCUSSION

We describe an extremely rare case of GOO, which can be easily corrected with cholecystectomy. Removal of the gallbladder removes the root cause of the issue, and should be first line therapy unless the patient is unfit for surgery.

CONCLUSION

This extremely rare cause of GOO should be recognized, and treated promptly with surgery if possible.

Laparoscopic Liver Resection Difficulty Score-a Validation Study

OBJECTIVE(S)

The technical complexity of laparoscopic liver resection (LLR) poses unique challenges distinct from open surgery. An objective scoring system was developed that preoperatively quantifies the difficulty of LRR to help guide surgeon decision-making regarding the feasibility and safety of minimally invasive approaches. The aim of this multiinstitutional study was to externally validate this scoring system.

METHODS

Patients who underwent LLR at two institutions were reviewed. LLR difficulty score (LDS) was calculated based on patient, tumor, and anatomic characteristics by two independent, blinded hepatobiliary surgeons. Surrogates of case complexity (e.g., conversion rate, operative time) were used for validation of this index.

RESULTS

From 2006 to 2016, 444 LLR were scored as low (n = 94), intermediate (n = 98), and high difficulty (n = 152) with respective conversion rates of 5.3%, 15.7%, and 25%. Cases of higher LDS correlated with larger mean blood loss (203 ml vs. 331 ml vs. 635 ml). Mean operative and Pringle maneuver used were associated with increasing LDS (155 min vs. 202 min vs. 315 min and 14.4% vs. 29.7% vs. 45.1% respectively). These operative surrogates of difficulty correlated significantly with the LDS (all p < 0.0001).

CONCLUSIONS

This comprehensive external validation of the LDS is robust and applicable in diverse patient populations. This LDS serves as a useful objective predictor of technical difficulty for LLR to help surgeons in selecting patients according to their individual operative experience and is valuable for preoperative risk estimation and stratification in randomized trials.

Using δ13C of Levoglucosan As a Chemical Clock

Compound specific carbon isotopic measurements (δ¹³C) of levoglucosan were carried out for ambient aerosol sampled during an intensive biomass burning period at different sites in Guangdong province, China. The δ¹³C of ambient levoglucosan was found to be noticeably heavier than the average δ¹³C of levoglucosan found in source C3-plant-combustion samples. To estimate the photochemical age of sampled ambient levoglucosan, back trajectory analyses were done. The origin and pathways of the probed air masses were determined, using the Lagrangian-particle-dispersion-model FLEXPART and ECMWF meteorological data. On the other hand, the isotopic hydrocarbon clock concept was applied to relate the changes in the field-measured stable carbon isotopic composition to the extent of chemical processing during transport. Comparison of the photochemical age derived using these two independent approaches shows on average good agreement, despite a substantial scatter of the individual data pairs. These analyses demonstrate that the degree of oxidative aging of particulate levoglucosan can be quantified by combining laboratory KIE studies, observed δ¹³C at the source and in the field, as well as back trajectory analyses. In this study, the chemical loss of levoglucosan was found to exceed 50% in one-fifth of the analyzed samples. Consequently, the use of levoglucosan as a stable molecular tracer may underestimate the contribution of biomass burning to air pollution.

A retrospective review of correlative radiological assessment and surgical exploration for hilar cholangiocarcinoma

Backgrounds/Aims

Hilar cholangiocarcinomas (HCCAs) are tumors that involve the biliary confluence; at present, radical surgery offers the only chance of long-term survival, but this can be challenging given the complexity of the hilar anatomy. Blumgart and Jarnagin described a preoperative staging system that incorporates the effect of local tumor extent and its impact on adjacent structures and that has been demonstrated to correlate better with actual surgical resectability. The primary aim of this study is to describe the correlation between preoperative Blumgart-Jarnagin staging and its correlation with surgical resectability.

Methods

Patients who underwent surgical resection for hilar cholangiocarcinoma at Singapore General Hospital between January 1, 2002, and January 1, 2013, were identified from a prospectively maintained institutional database. All patients were staged based on the criteria described by Blumgart and Jarnagin. Correlation with surgical resectability was then determined.

Results

A total of 19 patients were identified. Overall resectability was 57.8% (n=11). Patients with Blumgart-Jarnagin stage T1 had the highest rates of resectability at 80%; patients with stage T2 and T3 disease had resectability rates of 25% and 40% respectively. Median overall survival was 13.6 months.

Conclusions

The Blumgart-Jarnagin staging system is useful for predicting tumor resectability in HCCA.

Predictors of post-hepatectomy liver failure in patients undergoing extensive liver resections for hepatocellular carcinoma

Backgrounds/Aims

To determine the prevalence of post-hepatectomy liver failure/insufficiency (PHLF/I) in patients undergoing extensive hepatic resections for hepatocellular carcinoma (HCC) and to assess the predictive value of preoperative factors for post-hepatectomy liver failure or insufficiency (PHLF/I).

Methods

A retrospective review of patients who underwent liver resections for HCC between 2001 and 2013 was conducted. Preoperative parameters were assessed and analyzed for their predictive value of PHLF/I. Definitions used included the 50–50, International Study Group of Liver Surgery (ISGLS) and Memorial Sloan Kettering Cancer Centre (MSKCC) criteria.

Results

Among the 848 patients who underwent liver resections for HCC between 2001 and 2013, 157 underwent right hepatectomy (RH) and extended right hepatectomy (ERH). The prevalence of PHLF/I was 7%, 41% and 28% based on the 50–50, ISGLS and MSKCC criteria, respectively. There were no significant differences in PHLF/I between RH and ERH. Model for End-Stage Liver Disease (MELD) score and bilirubin were the strongest independent predictors of PHLF/I based on the 50–50 and ISGLS/MSKCC criteria, respectively. Predictive models were developed for each of the criteria with multiple logistic regression.

Conclusions

MELD score, bilirubin, alpha-fetoprotein and platelet count showed significant predictive value for PHLF/I (all p<0.05). A composite score based on these factors serves as guideline for physicians to better select patients undergoing extensive resections to minimize PHLF.

Abstract 5725: Systematic identification of tumour-specific neoantigens(by whole-genome sequencing) and correlation between tumour neoantigen burden, PD-L1 expression and immune infiltrates in 158Asian colorectal cancers

Background: Somatic mutations are attractive therapeutic targets for “individualized neoantigen vaccines” because of lack of host central tolerance and reduced risk of autoimmunity. Here, we perform large-scale-omic analyses to assess the neoantigen landscape of colorectal cancer (CRC), a cancer largely refractory to immune-checkpoint inhibition.

Methods: We performed whole genome sequencing (WGS) (60x tumor, 30x normal) and deep whole transcriptomic sequencing (RNA-Seq) (∼200x106 reads per tumor) on 158 colorectal cancers of which 32 are microsatellite instability high (MSI-H) tumours and 126 are microsatellite stable (MSS). Whole exome sequencing (200x tumor, 100x normal) was also performed on 120 tumours. HLA typing, somatic mutations, gene expression and neoepitope predictions were computationally evaluated. Inferred HLA-A alleles were orthogonally validated with Pacbio long-read sequencing. Tissue microarrays (TMAs) with tumour core, tumour edge and normal adjacent tissue of these 158 CRCs were constructed. Histopathological analyses using multiplex immunohistochemistry (mIHC) to simultaneously evaluate 7 markers, i.e. cytokeratin (CK), CD3, CD8, FOXP3, CD68, PD-L1, DAPI, have been performed.

Results: The most common HLAs were, by allele count: A*11:01: 56; A*33:03: 38; B*58:01: 33; B*46:01: 29; B*40:01: 26; C*01:02: 41; C*07:02: 33. Inferred HLA-A alleles from WGS data was largely concordant (&gt;90%) with Pacbio long-read sequencing. There were a median of 2,850 (1229-6909) [MSI] & 213 (27-13,835) [MSS] coding variants, from which 10,487 (4,307-27,365) [MSI] & 726.5 (50-59,096) [MSS] possible neoepitopes were derived, after accounting for epitope processing, the normal proteome and general population variome based on dbSNP, Of these, 5,707 (2,608-15,218) [MSI] & 320 (14-25,243) [MSS] neoepitopes are expressed (based on RNA-Seq). Epitope prediction algorithms revealed a median of 423 (17-1,056) [MSI] & 26 (0-1,102) [MSS] bound & expressed neoepitopes. 5 MSS tumors did not have any predicted bound nor expressed neoepitopes, 112 of 126 (89%) of MSS tumors had at least 5 predicted bound, expressed neoepitopes. Histopathological correlations between extent of immune infiltrates in fixed tissues, tumour PD-L1 expression and neoantigen burden is ongoing.

Conclusions: There is substantial variability in the neoantigen landscape amongst MSI & MSS CRCs. MSI contains multiple-fold higher neo-antigens. Amongst MSS tumours, 89% of patients have at least 5 predicted bound and expressed neo-epitopes that could be targeted in neoantigen-based vaccines for personalized immunotherapy.

Citation Format: Si-Lin Koo, Joe Poh Sheng Yeong, Andy Nguyen, Clarinda Wei Ling Chua, J Zachary Sanborn, Steve Benz, Wah Siew Tan, Choong Leong Tang, Su Yan, Min Hoe Chew, Brian Goh, Chung Yip Chan, Xiao Qing Koh, Alexander Lezhava, Tony Kiat Hon Lim, Shahrooz Rabizadeh, Anders Skanderup, Iain Beehuat Tan. Systematic identification of tumour-specific neoantigens(by whole-genome sequencing) and correlation between tumour neoantigen burden, PD-L1 expression and immune infiltrates in 158Asian colorectal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5725.

BCLC subclassification and tumour characteristics to provide prognostication of outcomes in an Asian population of locally advanced hepatocellular carcinoma treated using selective internal radiation therapy with Yttrium-90

443

Background: Selective internal radiation therapy (SIRT) with Yttrium-90 (Y90) is preferentially used in locally advanced hepatocellular carcinoma (HCC) patients in the Barcelona clinic liver cancer (BCLC) B or C cohort. However, the BCLC B cohort has a wide heterogeneity. To address this, Bolondi et al. proposed a BCLC B subclassification system. Additionally, the BCLC C cohort is also diverse in their Child-Pugh (CP) stage and extent of portal vein thrombosis (PVT). The effect of these subclassifications on survival outcomes has not been studied in HCC patients treated using SIRT. Methods: 392 HCC patients treated using SIRT from 1st January 2008 to 17th March 2017 were analyzed. These patients were classified according to the proposed subclassification system for the BCLC B cohort, and CP stage for the BCLC C cohort, and their survival outcomes reviewed. Results: 293 patients met the study’s inclusion criteria. For B1/B2/B3/B4/ C CP-A and C CP-B, the median OS was 48.3/28.7/14.4/13.7/12.8 and 6.6 months respectively. Overall comparison between the subgroups for median OS reached statistical significance (p < 0.001). The Cox proportional-hazards regression analysis found that tumour location defined as unilobar or bilobar disease significantly influenced median OS. In the BCLC C cohort, the extent of portal vein invasion significantly influenced median OS (p < 0.001). For the BCLC C CP-A group, median OS for segmental/sectoral branch invasion, right and/or left portal vein invasion and main portal vein trunk invasion was 24.1, 12.8 and 6.5 months respectively. Conclusions: Bolondi et al.’s subclassification system optimizes prognostic prediction by reducing the clinical heterogeneity in BCLC B HCC patients treated using SIRT. However tumour location, unaccounted for in the proposed subclassification, is also an important prognosticator. For the BCLC C cohort CP stage, extent of PVT, and tumour location were important predictors of treatment outcomes.

Surgical management decreases disease recurrence risk in recurrent pyogenic cholangitis

BACKGROUND

Recurrent pyogenic cholangitis (RPC) has a high risk of disease recurrence. We present our experience with RPC and examine the factors associated with disease recurrence.

METHODS

We performed a retrospective review of all patients with RPC treated at two tertiary institutions between January 1990 and December 2013. Patients with liver atrophy and/or abscess were categorized as being associated with parenchymal disease (PD).

RESULTS

We studied 157 patients with a median age of 59.0 (interquartile range (IQR): 47.0-70.0) years and a median follow-up duration of 71.0 (IQR: 26.0-109.0) months. There were 64 (40.8%) and 93 (59.2%) patients with and without associated PD, respectively. Disease recurrence rate was 43.9% in our overall cohort through the course of follow-up. Surgical treatment was an independent prognostic factor for decreased disease recurrence risk (hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.18-0.87, P = 0.021). Stratified analysis revealed that liver resection was prognostic for lower risk of disease recurrence among patients with PD (HR 0.38, 95% CI 0.15-0.94, P = 0.036), while biliary bypass was prognostic for lower risk of disease recurrence among patients without PD (HR 0.30, 95% CI 0.15-0.61, P = 0.001). The overall post-operative complication rate among surgically treated patients was 31.1%, and the presence of bilobar stones was found to be independently associated with higher odds of post-operative complications (odds ratio 3.51, 95% CI 1.26-9.81, P = 0.017).

CONCLUSION

Surgical treatment is associated with decreased recurrence risk in RPC, but with significant post-operative morbidity. Where surgery is deemed appropriate, patients with and without PD are likely to benefit from liver resection and biliary bypass, respectively.

Spontaneous regression of pancreatic cancer: A case report and literature review

INTRODUCTION

Spontaneous regression of cancer is defined as the partial or complete disappearance of malignant disease without treatment, or in the presence of therapy that is deemed inadequate to exert an influence on malignant disease, as composed by Tilden Everson and Warren Cole in the 1960s. It has been a topic of major interest in the field of medical and surgical oncology. It is poorly understood and scantily documented. Factors associated and postulated pathogeneses are at best, hypothetical.

PRESENTATION OF CASE

We report a case of spontaneous resolution of a head of pancreas carcinoma in a 77-year-old gentleman after a myocardial infarction event delayed planned surgery.

DISCUSSION

A literature review of previously reported cases of spontaneous regression of pancreatic cancer was performed. The possible predisposing factors to spontaneous regression of pancreatic and other forms of malignancies was reviewed.

CONCLUSION

This is a novel case of spontaneous regression of pancreatic carcinoma after an episode of myocardial infarction. The pathophysiology to spontaneous resolution of cancer is not well understood, may be multifactorial and requires further study.

A Retrospective Review of the Diagnostic and Management Challenges of Mirizzi Syndrome at the Singapore General Hospital

BACKGROUND

Mirizzi syndrome (MS) occurs when gallstone impaction in Hartmann's pouch results in extrinsic obstruction of the common bile duct, and fistulation may occur.

METHODS

We retrospectively reviewed electronic records of patients surgically treated for MS from November 2001 to June 2012. Patient presentations, diagnostic methods, treatments and complications were recorded.

RESULTS

Sixty-four patients were grouped according to a classification proposed by Beltran et al. [World J Surg 2008; 32: 2237-2243]. Forty-three (66.2%), 18 (27.7%) and 3 (4.6%) patients were classified as types I, II, and III respectively. Magnetic-resonance-cholangiopancreaticography was the most sensitive imaging modality, suggesting MS in 24 (88.9%), followed by CT scan (40%) and ultrasonography (11.4%). Forty-four underwent Endoscopic-retrograde-cholangiopancreaticography and 29 (65.9%) suggested the presence of MS. MS was accurately diagnosed pre-operatively in 48 (73.8%) patients. In type I, 40 (93.0%) patients underwent cholecystectomy, while 3 required hepaticojejunostomy. In type II, 12 (66.7%) underwent cholecystectomy and 5 (27.8%) required hepatico-enteric anastomosis. In type III, 1 underwent cholecystectomy and 2 (66.7%) required hepatico-enteric anastomosis. Laparoscopic cholecystectomy was attempted in 20 (30.8%) patients and 13 (65.0%) required conversion. Twenty-nine (44.6%) underwent intra-operative-cholangioscopy, 30 (46.2%) underwent intra-operative-cholangiogram and 41 (63.1%) underwent intra-operative T-tube placement. Six (9.2%) experienced intra-operative complications, 12 (18.5%) experienced post-operative complications and 10 (15.4%) experienced late complications.

CONCLUSION

MS is a challenging condition and multimodal diagnostic approach has the greatest yield in achieving accurate pre-operative diagnosis. If suspicion is high, a trial of laparoscopic dissection with low threshold for open conversion is recommended.

Prediction of Hepatocellular Carcinoma Recurrence Beyond Milan Criteria After Resection: Validation of a Clinical Risk Score in an International Cohort

OBJECTIVE

This study aims to validate a previously reported recurrence clinical risk score (CRS).

SUMMARY OF BACKGROUND DATA

Salvage transplantation after hepatocellular carcinoma (HCC) resection is limited to patients who recur within Milan criteria (MC). Predicting recurrence patterns may guide treatment recommendations.

METHODS

An international, multicenter cohort of R0 resected HCC patients were categorized by MC status at presentation. CRS was calculated by assigning 1 point each for initial disease beyond MC, multinodularity, and microvascular invasion. Recurrence incidences were estimated using competing risks methodology, and conditional recurrence probabilities were estimated using the Bayes theorem.

RESULTS

From 1992 to 2015, 1023 patients were identified, of whom 613 (60%) recurred at a median follow-up of 50 months. CRS was well validated in that all 3 factors remained independent predictors of recurrence beyond MC (hazard ratio 1.5-2.1, all P < 0.001) and accurately stratified recurrence risk beyond MC, ranging from 19% (CRS 0) to 67% (CRS 3) at 5 years. Among patients with CRS 0, no other factors were significantly associated with recurrence beyond MC. The majority recurred within 2 years. After 2 years of recurrence-free survival, the cumulative risk of recurrence beyond MC within the next 5 years for all patients was 14%. This risk was 12% for patients with initial disease within MC and 17% for patients with initial disease beyond MC.

CONCLUSIONS

CRS accurately predicted HCC recurrence beyond MC in this international validation. Although the risk of recurrence beyond MC decreased over time, it never reached zero.