One-stage resection for Bismuth type IV hilar cholangiocarcinoma with high hilar resection and parenchyma-preserving strategies: a cohort study

Primary neuroendocrine tumour of the extrahepatic biliary duct

Neuroendocrine tumours of the extrahepatic bile ducts are extremely rare, accounting for only 0.2-2% of gastrointestinal tract neuroendocrine neoplasms. Here, we present an incidental finding of this rare tumour, identified during staging scans post-resection of a malignant rectosigmoid polyp and treated with resection and biliary reconstruction. A suspicious, arterially enhancing porta hepatis lymph node was identified on CT and further investigated with liver MRI and 68Ga DOTATATE PET. These revealed a lobulated lesion of the hilum which showed marked avidity without metastases. The patient underwent a successful radical resection of the extrahepatic biliary ducts (including the left, right and common hepatic ducts), the common bile duct and hepaticojejunostomy formation. Histology revealed a 20-mm well-differentiated NET, WHO Grade 2. Two years later, the patient is alive and well without recurrence. This fascinating case illustrates the importance of thorough preoperative planning of surgical resection for tumours at an unusual primary site.

Cholangiocarcinoma: The Current Status of Surgical Options including Liver Transplantation

Cholangiocarcinoma (CCA) poses a substantial threat as it ranks as the second most prevalent primary liver tumor. The documented annual rise in intrahepatic CCA (iCCA) incidence in the United States is concerning, indicating its growing impact. Moreover, the five-year survival rate after tumor resection is only 25%, given that tumor recurrence is the leading cause of death in 53-79% of patients. Pre-operative assessments for iCCA focus on pinpointing tumor location, biliary tract involvement, vascular encasements, and metastasis detection. Numerous studies have revealed that portal vein embolization (PVE) is linked to enhanced survival rates, improved liver synthetic functions, and decreased overall mortality. The challenge in achieving clear resection margins contributes to the notable recurrence rate of iCCA, affecting approximately two-thirds of cases within one year, and results in a median survival of less than 12 months for recurrent cases. Nearly 50% of patients initially considered eligible for surgical resection in iCCA cases are ultimately deemed ineligible during surgical exploration. Therefore, staging laparoscopy has been proposed to reduce unnecessary laparotomy. Eligibility for orthotopic liver transplantation (OLT) requires certain criteria to be granted. OLT offers survival advantages for early-detected unresectable iCCA; it can be combined with other treatments, such as radiofrequency ablation and transarterial chemoembolization, in specific cases. We aim to comprehensively describe the surgical strategies available for treating CCA, including the preoperative measures and interventions, alongside the current options regarding liver resection and OLT.

Parenchyma-Preserving Hepatectomy in Perihilar Cholangiocarcinoma: A Chance for Critical Patients?

Introduction

Surgery for perihilar cholangiocarcinoma (pCCA) is associated with high rates of postoperative morbidity and mortality. Extended liver resection (EXT) increases R0 resection rate and survival; however, patients with high perioperative risk are not suitable for extended resection. This study aimed to compare overall survival and surgical morbidity in patients with extended liver resection and parenchyma-preserving hepatectomy (PPH).

Methods

Between January 2010 and November 2020, 113 consecutive patients with pCCA underwent surgery at our institution. Eighty-two patients were resected in curative intent. Sixty-four patients received extended liver resection, and 18 patients PPH. Outcomes of resections were evaluated.

Results

There was no significant difference in overall survival in patients with PPH compared to extended liver resection (log-rank p = 0.286). Patients with PPH experienced lower rates of postoperative morbidity and mortality. There was no case of in-house mortality in PPH-resected patients compared to 10 cases (16%) in patients that received EXT (p = 0.073).

Conclusion

PPH shows similar overall survival with lower rates of postoperative morbidity and mortality. Our findings support the role of a PPH, in selected patients with pCCA, that are not suitable for extended resection due to increased perioperative risk.

Impact of surgery on survival outcomes for Bismuth type IV Klatskin tumors

BACKGROUND

Bismuth-Corlette type IV Klatskin tumors have conventionally been considered unresectable. This retrospective study aimed to demonstrate the survival improvement of patients with type IV Klatskin tumors when resected and suggest possible radiological features for R0 resectability.

METHODS

Data on type IV Klatskin tumors diagnosed between 2008 and 2019 were reviewed retrospectively. Patients with distant metastasis, concomitant other cancers at the initial state, extensive vascular invasions, poor liver function, and poor general condition were excluded. The survival outcomes of patients and radiologic parameters of bile duct tumors were compared between the curative resection (R0, 1 resection) and non-resection groups.

RESULTS

The demographic findings of patients with curative resection (n = 48) and non-resection (n = 111) were comparable. Both were potentially resectable in the initial state. The postoperative morbidity was 22.9% and the 90-day mortality 4.2%. There was a significant difference in the median survival among the curative-intended resection, palliative treatment, and supportive care groups (35, 16, and 12 months, respectively; P < 0.001).

DISCUSSION

In patients with type IV Klatskin tumor without extensive tumor invasion into adjacent tissues, including major vessels, surgical resection can be considered for better survival.

CLINICAL REGISTRATION NUMBER

IRB No. 2009-100-1157.

Locally advanced gallbladder cancer treated with effective chemotherapy and subsequent curative resection: a case report

Background

Surgical resection of gallbladder cancer with negative margins is the only potentially curative therapy. Most patients with gallbladder cancer are diagnosed in an advanced stage and, despite the availability of several chemotherapies, the prognosis remains dismal. We report a case of locally advanced gallbladder cancer that was successfully treated with effective cisplatin plus gemcitabine, followed by curative resection.

Case presentation

A 55-year-old Japanese female was hospitalized with right hypochondrial pain. Enhanced computed tomography revealed a 49 × 47 mm mass at the neck of the gallbladder, with suspected invasion of the liver and right hepatic artery. Endoscopic retrograde cholangiopancreatography demonstrated displacement of the upper bile duct. Intraductal ultrasonography showed irregular wall thickening and disappearance of the wall structure in bile ducts from the B4 branch to distal B2 and B3. Percutaneous transhepatic biliary biopsy revealed a poorly differentiated carcinoma. The patient was diagnosed with unresectable gallbladder cancer (T4N0M0 stage IVA). Cisplatin plus gemcitabine chemotherapy was initiated. After six courses of chemotherapy, enhanced computed tomography showed that the mass in the neck of the gallbladder had shrunk to 30 mm, Endoscopic retrograde cholangiopancreatography showed improvement of the hilar duct stenosis. A biopsy of the bile duct mucosa showed no malignant cells in the branch of the left and right hepatic ducts, the left hepatic duct, or the intrapancreatic ducts. The patient underwent conversion surgery with right and segment 4a liver resection, extrahepatic duct resection, and cholangiojejunostomy. The histopathologic diagnosis showed that the tumor cells had shrunk to 2 × 1 mm, and that R0 resection of the T2aN0M0 stage IIA tumor was successful.

Conclusion

Although conversion surgery for gallbladder cancer is rarely possible, curative resection may offer a better prognosis, and it is important to regularly pursue possibilities for surgical resection even during chemotherapy.

Modification and comparison of CT criteria in the preoperative assessment of hepatic arterial invasion by hilar cholangiocarcinoma

OBJECTIVE

To compare the diagnostic performance of three CT criteria and two signs in evaluating hepatic arterial invasion by hilar cholangiocarcinoma.

METHODS

In this study, we retrospectively reviewed the CT images of 85 patients with hilar cholangiocarcinoma. Modified Loyer's, Lu's, and Li's standards were used to evaluate hepatic arterial invasion by hilar cholangiocarcinoma with the reference of intraoperative findings and/or the postoperative pathological diagnosis. Arterial tortuosity and contact length were also evaluated.

RESULTS

Loyer's, Lu's, and Li's standards showed sensitivities of 91.7%, 90.3%, and 72.2%, specificities of 94.0%, 94.5%, and 95.6%, and accuracies of 93.3%, 93.3%, and 89.0%, respectively, in evaluating hepatic arterial invasion by hilar cholangiocarcinoma. Loyer's and Lu's standards and contact length performed better than Li's standard (P < 0.001). Arterial tortuosity performed worse than other criteria (P < 0.001). The CT criteria performed best in evaluating proper hepatic arterial invasion compared with the left and right hepatic artery. When the cut-off contact length of 6.73 mm was combined with Loyer's standard, 4 false-negative cases could be avoided.

CONCLUSIONS

Loyer's and Lu's standards and the contact length performed best in evaluating hepatic arterial invasion by hilar cholangiocarcinoma on preoperative CT images, particularly in assessing the proper hepatic artery. Arterial tortuosity could serve as an important supplement. The combination of the contact length and Loyer's standard could improve the diagnostic performance.

Minimally invasive surgery for hilar cholangiocarcinoma: a multicenter retrospective analysis of 158 patients

BACKGROUND

Curative resection of hilar cholangiocarcinoma (HC) is typically carried out using open surgery. In the present study, we examined the safety (postoperative complication) and effectiveness (resection margin status and patient survival) of minimally invasive surgery (MIS) for HC.

METHODS

This retrospective analysis included 158 patients receiving MIS for HC at 10 participating centers between December 2013 and November 2019. Patient demographics, surgical outcomes, and oncological outcomes were retrospectively analyzed.

RESULTS

Clinical information obtained from 10 different clinical centers did not show any evident cohort-bias clustering. One hundred and twenty-six (79.7%) patients underwent LRHC, 12 (7.6%) patients underwent RARHC, conversion to an open procedure occurred in 20 (12.7%) patients. The operation time and estimated blood loss were 410.8 ± 128.9 min and 477.8 ± 706.3 mL, respectively. The surgical radicality of the 158 patients was R0, 129 (81.6%); R1, 20 (18.4%) and R2, 9 (5.7%). Grades I-II complications was occurred in 68 (43.0%) patients. Severe morbidity (grade III-V) occurred in 14 (8.7%) patients. The median overall survival in whole cohort was 25.4 months. The overall survival rate was 67.6% at year 1, 28.8% at year 3, and 19.2% at year 5. Comparing the first half of MISHC performed by each center with the following cases, the operation time and postoperative hospital stay does not decrease with the increasing cases. On literature review, MISHC is non-inferior to open surgery at least in perioperative period.

CONCLUSIONS

In this Chinese MIS for HC multicenter study, the largest to date, long-term overall survival rates after MIS appear comparable to those reported in current open series. Further randomized controlled trials are necessary to assess the global impact of MISHC.

Survival outcomes of hepatic resections in Bismuth-Corlette type IV cholangiocarcinoma

BACKGROUND

Surgical resection for Bismuth-Corlette type IV (BC-IV) hilar cholangiocarcinomas, also termed Klatskin tumours are technically challenging and were once considered unresectable tumours. Following advances in hepatobiliary imaging and surgical techniques, emerging evidence suggests that surgical resection is a viable avenue for long-term survival. We aimed to identify factors affecting survival outcomes of hepatic resections for BC-IV cholangiocarcinomas.

METHOD

A systematic review was performed across multiple databases and several clinical trial registries. Two reviewers independently screened and selected papers that contained survival data on BC-IV cholangiocarcinoma after hepatic resections.

RESULTS

Of 13 499 papers from our search result, 21 papers satisfied the inclusion criteria. The median post-operative survival was 30.8 months. The average 1- and 5-year post-operative survivals were 61.6 and 33.3%, respectively. Predictors of long-term survival included achievement of R0 margins, minimisation of operative time and reduction intra-operative blood loss.

CONCLUSION

Our analysis demonstrates improving post-operative outcomes and survival in surgical resection of BC-IV cholangiocarcinoma and suggests that radical surgical resection is a valid treatment option for the disease.

Current Endoscopic Management of Malignant Biliary Stricture

Biliary and pancreatic cancers occur silently in the initial stage and become unresectable within a short time. When these diseases become symptomatic, biliary obstruction, either with or without infection, occurs frequently due to the anatomy associated with these cancers. The endoscopic management of these patients has changed, both with time and with improvements in medical devices. In this review, we present updated and integrated concepts for the endoscopic management of malignant biliary stricture. Endoscopic biliary drainage had been indicated in malignant biliary obstruction, but the concept of endoscopic management has changed with time. Although routine endoscopic stenting should not be performed in resectable malignant distal biliary obstruction (MDBO) patients, endoscopic biliary drainage is the treatment of choice for palliation in unresectable MDBO patients. Self-expanding metal stents (SEMS) have better stent patency and lower costs compared with plastic stents (PS). For malignant hilum obstruction, PS and uncovered SEMS yield similar short-term outcomes, while a covered stent is not usually used due to a potential unintentional obstruction of contralateral ducts.

Clinical practice of basin-shaped hepaticojejunostomy following hilar resection of stage III/IV hilar cholangiocarcinoma

Background

Radical surgery for Bismuth type III/IV hilar cholangiocellular carcinoma, which was usually considered unresectable, seems to improve prognosis by increasing the surgical curability rate. However, the dilemma of multiple billiary stumps and high postoperative complication rate caused by hepato-enteric anastomosis has been the main impediment. Thus, we practiced and introduce a new technique called “basin-shaped” hepaticojejunostomy to improve the treatment.

Methods

Thirty-two cases with Bismuth type III/IV hilar cholangiocarcinoma admitted to our department from Aug. 2013 to Dec. 2015 and who underwent hilar resection and resection segment 4(or plus resection segment 1) were reconstructed by “basin-shaped” hepaticojejunostomy. The clinical data were collected and analyzed.

Results

All patients underwent successful R0 high hilar resection following basin-shaped hepaticojejunostomy and were discharged from the hospital without severe postoperative complications. The average operation time for hepato-enteric anastomosis was 42.1 ± 8.5 min. The postoperative bile leakage rate was 3.1% (1/32), and the biliary infection rate was 6.2% (2/32). Within a median follow-up of 25.6 months, none of the patients developed local recurrence around the hepato-enteric anastomosis.

Conclusions

For patients with Bismuth type III/IV hilar cholangiocellular carcinoma who underwent resection segment 4(or plus resection segment 1), basin-shaped hepaticojejunostomy was a safe, simple and valid method for bile duct reconstruction, with a relatively low incidence of postoperative complications.

Morbidity and mortality after major liver resection in patients with perihilar cholangiocarcinoma: A systematic review and meta-analysis

BACKGROUND

Morbidity and mortality after hepatectomy for perihilar cholangiocarcinoma are known to be high. However, reported postoperative outcomes vary, with notable differences between Western and Asian series. We aimed to determine morbidity and mortality rates after major hepatectomy in patients with perihilar cholangiocarcinoma and assess differences in outcome regarding geographic location and hospital volume.

METHODS

A systematic review was performed by searching the MEDLINE and EMBASE databases through November 20, 2017. Risk of bias was assessed and meta-analysis and metaregression were performed using a random effects model.

RESULTS

A total of 51 studies were included, representing 4,634 patients. Pooled 30-day and 90-day mortality were 5% (95% CI 3%-6%) and 9% (95% CI 6%-12%), respectively. Pooled overall morbidity and severe morbidity were 57% (95% CI 50%-64%) and 40% (95% CI 34%-47%), respectively. Western studies compared with Asian studies had a significantly higher 30-day mortality, 90-day mortality, and overall morbidity: 8% versus 2% (P < .001), 12% versus 3% (P < .001), and 63% versus 54% (P = .048), respectively. This effect on mortality remained significant after correcting for hospital volume. Univariate metaregression analysis showed no influence of hospital volume on mortality or morbidity, but when corrected for geographic location, higher hospital volume was associated with higher severe morbidity (P = .039).

CONCLUSION

Morbidity and mortality rates after major hepatectomy for perihilar cholangiocarcinoma are high. The Western series showed a higher mortality compared with the Asian series, even when corrected for hospital volume. Standardized reporting of outcomes is necessary. Underlying causes for differences in outcomes between Asian and Western centers, such as differences in treatment strategies, should be further analyzed.

Diagnosis and Management of Intrahepatic and Extrahepatic Cholangiocarcinoma

Cholangiocarcinomas (CC) are rare tumors which usually present late and are often difficult to diagnose and treat. CCs are categorized as intrahepatic, hilar, or extrahepatic. Epidemiologic studies suggest that the incidence of intrahepatic CCs may be increasing worldwide. In this chapter, we review the risk factors, clinical presentation, and management of cholangiocarcinoma.

The Surgical Management of Klatskin Tumours: Has Anything Changed in the Last Decade?

Surgical treatment of hilar cholangiocarcinomas requires complex pre-, intra- and post-operative decision-making. Despite the significant progress in liver surgery over the years, several issues such as the role of pre-operative biliary drainage, portal vein embolisation, staging laparoscopy and neo-adjuvant chemotherapy remain unresolved. Operative strategies such as vascular resection, caudate lobe resection and liver transplant have also been practiced in order to improve R0 resectability and improved survival. The review aims to consolidate evidence from major studies in the last 11 years. Survival data were only included from studies that reported the results in at least 30 patients with 1-year follow-up. A significant number of patients may be prevented an unnecessary laparotomy if they underwent a staging laparoscopy. There remain no guidelines as to when portal vein embolisation or pre-operative biliary drainage should be employed but most studies agree with pre-operative biliary drainage being an absolute indication if portal vein embolisation is performed. Concomitant hepatectomy and caudate lobectomy increases R0 resection but vascular resection cannot be routinely recommended. Liver transplant at specialised centres in selective patients has had impressive results. Guidelines are required for pre-operative biliary drainage and portal vein embolisation and randomised trials are required in order to define the role of vascular resection in achieving a R0 resection and increasing survival.

A New Surgical Procedure "Dumbbell-Form Resection" for Selected Hilar Cholangiocarcinomas With Severe Jaundice: Comparison With Hemihepatectomy

The aim of the study is to evaluate the therapeutic effect of a new surgical procedure, dumbbell-form resection (DFR), for hilar cholangiocarcinoma (HCCA) with severe jaundice. In DFR, liver segments I, IVb, and partial V above the right hepatic pedicle are resected.Hemihepatectomy is recognized as the preferred procedure; however, its application is limited in HCCAs with severe jaundice.Thirty-eight HCCA patients with severe jaundice receiving DFR and 70 receiving hemihepatectomy from January 2008 to January 2013 were included. Perioperative parameters, operation-related morbidity and mortality, and post-operative survival were analyzed.A total of 21.1% patients (8/38) in the DFR group received percutaneous transhepatic biliary drainage (PTBD), which was significantly <81.4% (57/70) in the hemihepatectomy group. The TBIL was higher in the DFR group at operation (243.7 vs 125.6 μmol/L, respectively). The remnant liver volume was significantly higher after DFR. The operation-related morbidity was significantly lower after DFR than after hemihepatectomy (26.3% vs 48.6%, respectively). None of the patients died during the perioperative period after DFR, whereas 3 died after hemihepatectomy. There was no difference in margin status, histological grade, lymph-node involvement, and distant metastasis between the 2 groups. The 1-, 3-, and 5-year survival rates after DFR (68.4%, 32.1%, and 21.4%, respectively) showed no significant difference with those after hemihepatectomy (62.7%, 34.6%, and 23.3%, respectively). Kaplan-Meier analysis indicated that overall survival and recurrence after DFR demonstrated no significant difference compared with hemihepatectomy.DFR appears to be feasible for selected HCCA patients with severe jaundice. However, its indications should be restricted.

Is Liver Transplantation Appropriate for Patients with Potentially Resectable De Novo Hilar Cholangiocarcinoma?

BACKGROUND

Liver transplantation (LTX) is curative for selected patients with hilar cholangiocarcinoma (HC) in the setting of sclerosing cholangitis. However, the outcome of LTX vs liver resection (RTX) for patients with de novo HC remains unclear.

STUDY DESIGN

Patients with de novo HC treated by protocol LTX (n = 90) or RTX (n = 124) between 1993 and 2013 were reviewed. Based on preoperative imaging, RTX was pursued for Bismuth type III HC and LTX for unresectable Bismuth type IV.

RESULTS

Unadjusted analysis showed that overall survival after operation was greater for LTX than RTX (p = 0.003). One-, 3-, and 5-year overall survival rates, respectively, were 90%, 71%, and 59% for LTX and 81%, 53%, and 36% for RTX. Survival was not different between LTX and RTX after adjusting for patient age, lymph node metastases, and tumor size. After postoperative pathologic review, HC after RTX was reclassified as Bismuth-Corlette (B-C) IV, based on the necessity of multiple biliary anastomoses in 40 patients to more accurately compare treatment outcomes. Overall survival was greater after LTX than RTX (p = 0.039) for patients with Bismuth-Corlette IV HC.

CONCLUSIONS

Patients with clearly resectable de novo HC should be treated with resection because there is no evidence that they would fare better with LTX. Patients with locally unresectable de novo HC, meeting criteria for our protocol, should be treated with LTX. The decision to proceed with RTX or LTX for patients with borderline resectable de novo HC remains difficult, but our results suggest that patients with B-C type IV HC might be best treated with transplantation, if they are excellent transplant candidates.

Hilar cholangiocarcinoma: controversies on the extent of surgical resection aiming at cure

BACKGROUND

Hilar cholangiocarcinoma is the most common malignant tumor affecting the extrahepatic bile duct. Surgical treatment offers the only possibility of cure, and it requires removal of all tumoral tissues with adequate resection margins. The aims of this review are to summarize the findings and to discuss the controversies on the extent of surgical resection aiming at cure for hilar cholangiocarcinoma.

METHODS

The English medical literatures on hilar cholangiocarcinoma were studied to review on the relevance of adequate resection margins, routine caudate lobe resection, extent of liver resection, and combined vascular resection on perioperative and long-term survival outcomes of patients with resectable hilar cholangiocarcinoma.

RESULTS

Complete resection of tumor represents the most important prognostic factor of long-term survival for hilar cholangiocarcinoma. The primary aim of surgery is to achieve R0 resection. When R1 resection is shown intraoperatively, further resection is recommended. Combined hepatic resection is now generally accepted as a standard procedure even for Bismuth type I/II tumors. Routine caudate lobe resection is also advocated for cure. The extent of hepatic resection remains controversial. Most surgeons recommend major hepatic resection. However, minor hepatic resection has also been advocated in most patients. The decision to carry out right- or left-sided hepatectomy is made according to the predominant site of the lesion. Portal vein resection should be considered when its involvement by tumor is suspected.

CONCLUSION

The curative treatment of hilar cholangiocarcinoma remains challenging. Advances in hepatobiliary techniques have improved the perioperative and long-term survival outcomes of this tumor.

Prognostic factors and adjuvant treatments for surgically treated cancers of the biliary tract: a multicentre study of the Anatolian Society of Medical Oncology (ASMO)

BACKGROUND

Biliary tract cancers are rare, and surgical resection is the standard treatment at early stages. However, reports on the benefits of adjuvant treatment following surgical resection are conflicting. This study aimed to evaluate the factors affecting survival and adjuvant treatments in patients with surgically treated biliary tract cancers.

MATERIALS AND METHODS

Patient clinical features, adjuvant treatments, and efficacy and prognostic factor data were evaluated. Survival analyses were performed using SPSS 15.0.

RESULTS

The median overall survival was 30.7 months (95% confidence interval [CI], 18.4-42.9 months). Median survival was 19 months (95% CI, 6-33) for patients treated with fluorouracil based chemotherapy and 53 months (95% CI, 33.2-78.8) with gemcitabine based chemotherapy (p=0.033). On univariate analysis, poor prognostic factors for survival were galbladder localization, perineural invasion, hepatic invasion, a lack of adjuvant chemoradiotherapy treatment, and a lack of lymph node dissection. On multivariate analysis, perineural invasion was a poor prognostic factor (p=0.008).

CONCLUSIONS

Biliary tract cancers generally have poor prognoses. The main factors affecting survival are tumour localization, perineural invasion, hepatic invasion, adjuvant chemoradiotherapy, and lymph node dissection. Gemcitabine-based adjuvant chemotherapy is more effective than 5-fluorouracil-based chemotherapy.

Curative-intent surgery for hilar cholangiocarcinoma: prognostic factors for clinical decision making

BACKGROUND

The surgical approach for hilar cholangiocarcinoma (HC) has largely evolved, and increased resectability rates are reported. Large series of patients with resections for HC were published in the last years, and potential predictors for survival were explored. However, the usefulness of these predictors in clinical decision making is controversial.

PURPOSE

The aim of the present review is to explore the main prognostic factors after curative-intent surgery for HC, as emerged from the current literature. Furthermore, the impact of these predictors on clinical decision making is assessed.

CONCLUSION

An aggressive surgical approach has improved the survival rates in patients with HC and implies bile duct resection associated with liver resection and loco-regional lymph node dissection. The AJCC staging system remains the main tool to assess the prognosis after resection of HC. Margin-negative resections and absence of lymph node metastases are the main prognostic factor after curative-intent surgery for HC. Response to chemotherapy is also a prognostic factor. Markers of systemic inflammatory response might predict prognosis of patients with HC, but their usefulness in clinical decision making remains unclear.