JAK2 V617F mutation can be reliably detected in serum using droplet digital PCR.

INTRODUCTION: Detection of the JAK2 V617F mutation is a key step in the diagnosis of myeloproliferative neoplasms (MPN). Sensitive real-time quantitative PCR (qPCR) detection on peripheral blood (PB) is the most widely used method. The main objective of this study was to determine whether serum, the most common material available in archival biobanks, is a good liquid biopsy for detecting and quantifying the JAK2 V617F mutation using droplet digital PCR (ddPCR). METHODS: Paired PB and serum samples from 66 patients with MPN were used. Serum samples were frozen at -25°C before analysis. DNA was extracted from 200 µL PB and 400 µL serum, and ddPCR analysis was performed. RESULTS: Among the 47 patients with detectable mutation in their PB samples, the overall sensitivity for the detection of JAK2 mutation in serum was of 96% (45 of 47); V617F was detected in all cases where mutation load was above 1%. Our results showed very strong correlation between PB and serum (Spearman r: 0.989, P < .0001). Significantly higher allele burden was detected in serum compared to PB (Wilcoxon signed ranks test, Z = -5.672, P < .0001). CONCLUSION: In our study, JAK2 V617F mutation load as low as 1% was reliably detected in serum using ddPCR.

Prevention and management of adverse events of Novel agents in multiple myeloma: A consensus of the european myeloma network.

During the last few years, several new drugs have been introduced for treatment of patients with multiple myeloma, which have significantly improved treatment outcome. All of these novel substances differ at least in part in their mode of action from similar drugs of the same drug class, or are representatives of new drugs classes, and as such present with very specific side effect profiles. In this review, we summarize these adverse events, provide information on their prevention, and give practical guidance for monitoring of patients and for management of adverse events.Leukemia accepted article preview online, 18 December 2017. doi:10.1038/leu.2017.353.

Whole-body computed tomography versus conventional skeletal survey in patients with multiple myeloma: a study of the International Myeloma Working Group.

For decades, conventional skeletal survey (CSS) has been the standard imaging technique for multiple myeloma (MM). However, recently whole-body computed tomography (WBCT) has been implemented into the diagnostic criteria of MM. This analysis compares sensitivity and prognostic significance of WBCT and CSS in patients with smoldering MM (SMM) and MM. Fifty-four of 212 patients (25.5%) had a negative CSS and a positive WBCT for osteolytic lesions (P<0.0001). Of 66 patients with SMM based on CSS, 12 (22.2%) had osteolytic lesions on WBCT. In comparison, WBCT failed to detect some bone destructions in the appendicular skeleton possibly due to limitations of the field of view. Presence of lytic bone lesions in WBCT was of borderline prognostic significance (P=0.051) for SMM patients, with a median time to progression of 38 versus 82 months for those without bone destructions. In conclusion, WBCT identifies significantly more sites of bone destruction than CSS. More than 20% of patients with SMM according to CSS have in fact active MM detectable with WBCT. On the basis of this and other studies, WBCT (either computed tomography (CT) alone or as part of a positron emission tomography-CT protocol) should be considered the current standard for the detection of osteolytic lesions in MM.

Resection of synchronous liver metastases between radiotherapy and definitive surgery for locally advanced rectal cancer: short-term surgical outcomes, overall survival and recurrence-free survival.

AIM: There is debate as to the correct treatment algorithm sequence for patients with locally advanced rectal cancer with liver metastases. The aim of the study was to assess safety, resectability and survival after a modified 'liver-first' approach. METHOD: This was a retrospective study of patients undergoing preoperative radiotherapy for the primary rectal tumour, followed by liver resection and, finally, resection of the primary tumour. Short-term surgical outcome, overall survival and recurrence-free survival are reported. RESULTS: Between 2009 and 2013, 45 patients underwent liver resection after preoperative radiotherapy. Thirty-four patients (76%) received neoadjuvant chemotherapy, 24 (53%) concomitant chemotherapy during radiotherapy and 17 (43%) adjuvant chemotherapy. The median time interval from the last fraction of radiotherapy to liver resection and rectal surgery was 21 (range 7-116) and 60 (range 31-156) days, respectively. Rectal resection was performed in 42 patients but was not performed in one patient with complete response and two with progressive metastatic disease. After rectal surgery three patients did not proceed to a planned second stage liver (n = 2) or lung (n = 1) resection due to progressive disease. Clavien-Dindo ≥Grade III complications developed in 6.7% after liver resection and 19% after rectal resection. The median overall survival and recurrence-free survival in the patients who completed the treatment sequence (n = 40) were 49.7 and 13.0 months, respectively. Twenty of the 30 patients who developed recurrence underwent further treatment with curative intent. CONCLUSION: The modified liver-first approach is safe and efficient in patients with locally advanced rectal cancer and allows initial control of both the primary tumour and the liver metastases.

Intracellular glutathione determines bortezomib cytotoxicity in multiple myeloma cells.

Multiple myeloma (myeloma in short) is an incurable cancer of antibody-producing plasma cells that comprise 13% of all hematological malignancies. The proteasome inhibitor bortezomib has improved treatment significantly, but inherent and acquired resistance to the drug remains a problem. We here show that bortezomib-induced cytotoxicity was completely dampened when cells were supplemented with cysteine or its derivative, glutathione (GSH) in ANBL-6 and INA-6 myeloma cell lines. GSH is a major component of the antioxidative defense in eukaryotic cells. Increasing intracellular GSH levels fully abolished bortezomib-induced cytotoxicity and transcriptional changes. Elevated intracellular GSH levels blocked bortezomib-induced nuclear factor erythroid 2-related factor 2 (NFE2L2, NRF2)-associated stress responses, including upregulation of the xCT subunit of the Xc- cystine-glutamate antiporter. INA-6 cells conditioned to increasing bortezomib doses displayed reduced bortezomib sensitivity and elevated xCT levels. Inhibiting Xc- activity potentiated bortezomib-induced cytotoxicity in myeloma cell lines and primary cells, and re-established sensitivity to bortezomib in bortezomib-conditioned cells. We propose that intracellular GSH level is the main determinant of bortezomib-induced cytotoxicity in a subset of myeloma cells, and that combined targeting of the proteasome and the Xc- cystine-glutamate antiporter can circumvent bortezomib resistance.

High prevalence of hereditary thrombotic thrombocytopenic purpura in central Norway: from clinical observation to evidence.

UNLABELLED: Essentials The population prevalence of hereditary thrombotic thrombocytopenic purpura (TTP) is unknown. We studied the prevalence of hereditary TTP and population frequencies of two ADAMTS-13 mutations. A high frequency of hereditary TTP related to ADAMTS-13 mutation c.4143_4144dupA was found. Vicinity of ABO blood group and ADAMTS-13 loci may facilitate screening of ADAMTS-13 mutations. SUMMARY: Background Hereditary thrombotic thrombocytopenic purpura (TTP) caused by ADAMTS-13 mutations is a rare, but serious condition. The prevalence is unknown, but it seems to be high in Norway. Objectives To identify all patients with hereditary TTP in central Norway and to investigate the prevalence of hereditary TTP and the population frequencies of two common ADAMTS-13 mutations. Patients/Methods Patients were identified in a cross-sectional study within the Central Norway Health Region by means of three different search strategies. Frequencies of ADAMTS-13 mutations, c.4143_4144dupA and c.3178 C>T (p.R1060W), were investigated in a population-based cohort (500 alleles) and in healthy blood donors (2104 alleles) by taking advantage of the close neighborhood of the ADAMTS-13 and ABO blood group gene loci. The observed prevalence of hereditary TTP was compared with the rates of ADAMTS-13 mutation carriers in different geographical regions. Results We identified 11 families with hereditary TTP in central Norway during the 10-year study period. The prevalence of hereditary TTP in central Norway was 16.7 × 10(-6) persons. The most prevalent mutation was c.4143_4144dupA, accounting for two-thirds of disease causing alleles among patients and having an allelic frequency of 0.33% in the central, 0.10% in the western, and 0.04% in the southeastern Norwegian population. The allelic frequency of c.3178 C>T (p.R1060W) in the population was even higher (0.3-1%), but this mutation was infrequent among patients, with no homozygous cases. Conclusions We found a high prevalence of hereditary TTP in central Norway and an apparently different penetrance of ADAMTS-13 mutations.

Autologous stem cell transplantation versus novel drugs or conventional chemotherapy for patients with relapsed multiple myeloma after previous ASCT.

High-dose therapy (HDT) followed by autologous stem cell transplantation (ASCT) is the most common first-line treatment for patients with multiple myeloma (MM) under 65 years of age. A second ASCT at first relapse is frequently used but is challenged by the use of novel drugs. We retrospectively studied the outcome of second-line treatment in MM patients from the Nordic countries with relapse after first-line HDT and ASCT. Patients that underwent a second ASCT (n=111) were compared with patients re-treated with conventional cytotoxic drugs only (n=91) or with regimens including novel drugs (proteasome inhibitors and/or immunomodulatory drugs) (n=362) without a second ASCT. For patients receiving a second ASCT median overall survival was 4.0 years compared with 3.3 years (P<0.001) for the group treated with novel drugs and 2.5 years (P<0.001) for those receiving conventional cytotoxic drugs only. A second ASCT also resulted in a significantly longer second time to progression and a significantly longer time to next treatment. We conclude that, irrespective of the addition of novel drugs, MM patients in first relapse after ASCT still appear to benefit from a second ASCT. A second ASCT should be considered for all physically fit patients.

BRAF V600E mutation in early-stage multiple myeloma: good response to broad acting drugs and no relation to prognosis.

In this study, we analyzed the prevalence and clone size of BRAF V600E mutation in 209 patients with multiple myeloma and related the results to clinical phenotype, response and survival. Biopsies were screened for BRAF V600E by allele-specific real-time PCR (AS-PCR). Positive results were confirmed by immunohistochemistry, Sanger sequencing and, in three patients from whom we had stored purified myeloma cells, whole-exome sequencing. Eleven patients (5.3%) were BRAF V600E mutation positive by AS-PCR and at least one other method. The fraction of mutated cells varied from 4 to 100%. BRAF V600E-positive patients had no characteristic clinical phenotype except for significantly higher levels of serum creatinine (125 versus 86 µmol/l) Seven of eleven patients responded with at least very good partial response to alkylators, immunomodulatory agents or proteasome inhibitors. Progression-free and overall survival were similar in patients with and without the mutation. By this integrated approach, we found that patients with BRAF V600E mutation responded very well to broad acting drugs and there was no relation to prognosis in early-stage myeloma. In particular, a large mutated cell fraction did not correlate with aggressive disease.

High-frequency jet ventilation shortened the duration of gas embolization during laparoscopic liver resection in a porcine model.

BACKGROUND: Positive pressure mechanical ventilation causes rhythmic changes in thoracic pressure and central blood flow. If entrainment occurs, it could be easier for carbon dioxide to enter through a wounded vein during laparoscopic liver lobe resection (LLR). High-frequency jet ventilation (HFJV) is a ventilating method that does not cause pronounced pressure or blood flow changes. This study aimed to investigate whether HFJV could influence the frequency, severity, or duration of gas embolism (GE) during LLR. METHODS: Twenty-four anaesthetized piglets underwent lobe resection and were randomly assigned to either normal frequency ventilation (NFV) or HFJV (n=12 per group). During resection, a standardized injury to the left hepatic vein was created to increase the risk of GE. Haemodynamic and respiratory variables were monitored. Online blood gas monitoring and transoesophageal echocardiography were used. GE occurrence and severity were graded as 0 (none), 1 (minor), or 2 (major), depending on the echocardiography results. RESULTS: GE duration was shorter in the HFJV group (P=0.008). However, no differences were found between the two groups in the frequency or severity of embolism. Incidence of Grade 2 embolism was less than that found in previous studies and physiological responses to embolism were variable. CONCLUSION: HFJV shortened the mean duration of GE during LLR and was a feasible ventilation method during the procedure. Individual physiological responses to GE were unpredictable.

Bone morphogenetic protein-9 suppresses growth of myeloma cells by signaling through ALK2 but is inhibited by endoglin.

Multiple myeloma is a malignancy of plasma cells predominantly located in the bone marrow. A number of bone morphogenetic proteins (BMPs) induce apoptosis in myeloma cells in vitro, and with this study we add BMP-9 to the list. BMP-9 has been found in human serum at concentrations that inhibit cancer cell growth in vitro. We here show that the level of BMP-9 in serum was elevated in myeloma patients (median 176 pg/ml, range 8-809) compared with healthy controls (median 110 pg/ml, range 8-359). BMP-9 was also present in the bone marrow and was able to induce apoptosis in 4 out of 11 primary myeloma cell samples by signaling through ALK2. BMP-9-induced apoptosis in myeloma cells was associated with c-MYC downregulation. The effects of BMP-9 were counteracted by membrane-bound (CD105) or soluble endoglin present in the bone marrow microenvironment, suggesting a mechanism for how myeloma cells can evade the tumor suppressing activity of BMP-9 in multiple myeloma.

Bone morphogenetic proteins induce apoptosis in multiple myeloma cells by Smad-dependent repression of MYC.

Bone morphogenetic proteins (BMPs) have been shown to induce apoptosis and growth arrest in myeloma cells. However, the molecular mechanisms behind these events are not known. The MYC oncogene is a master regulator of cell growth and protein synthesis and MYC overexpression has been proposed to be associated with the progression of multiple myeloma. Here, we show that BMP-induced apoptosis in myeloma cells is dependent on downregulation of MYC. Moreover, the results suggest that targeting the MYC addiction in multiple myeloma is an efficient way of killing a majority of primary myeloma clones. We also found that myeloma cells harboring immunoglobulin (IG)-MYC translocations evaded BMP-induced apoptosis, suggesting a novel way for myeloma cells to overcome potential tumor suppression by BMPs.

The use of bisphosphonates in multiple myeloma: recommendations of an expert panel on behalf of the European Myeloma Network.

BACKGROUND: Bisphosphonates (BPs) prevent, reduce, and delay multiple myeloma (MM)-related skeletal complications. Intravenous pamidronate and zoledronic acid, and oral clodronate are used for the management of MM bone disease. The purpose of this paper is to review the current evidence for the use of BPs in MM and provide European Union-specific recommendations to support the clinical practice of treating myeloma bone disease. DESIGN AND METHODS: An interdisciplinary, expert panel of specialists on MM and myeloma-related bone disease convened for a face-to-face meeting to review and assess the evidence and develop the recommendations. The panel reviewed and graded the evidence available from randomized clinical trials, clinical practice guidelines, and the body of published literature. Where published data were weak or unavailable, the panel used their own clinical experience to put forward recommendations based solely on their expert opinions. RESULTS: The panel recommends the use of BPs in MM patients suffering from lytic bone disease or severe osteoporosis. Intravenous administration may be preferable; however, oral administration can be considered for patients unable to make hospital visits. Dosing should follow approved indications with adjustments if necessary. In general, BPs are well tolerated, but preventive steps should be taken to avoid renal impairment and osteonecrosis of the jaw (ONJ). The panel agrees that BPs should be given for 2 years, but this may be extended if there is evidence of active myeloma bone disease. Initial therapy of ONJ should include discontinuation of BPs until healing occurs. BPs should be restarted if there is disease progression. CONCLUSIONS: BPs are an essential component of MM therapy for minimizing skeletal morbidity. Recent retrospective data indicate that a modified dosing regimen and preventive measures can greatly reduce the incidence of ONJ.

Elevated serum concentrations of activated hepatocyte growth factor activator in patients with multiple myeloma.

OBJECTIVES: Hepatocyte growth factor (HGF) is a potential key factor in multiple myeloma. Conversion of pro-HGF to its active form is a critical limiting step for its biological effects. We aimed to examine the levels of the most potent activator, the hepatocyte growth factor activator (HGFA), in serum and bone marrow plasma of patients with multiple myeloma. METHODS: The activated form of HGFA was measured by an enzyme-linked immunosorbent assay in serum (n = 49) and bone marrow plasma (n = 16) from multiple myeloma patients, and in serum from healthy controls (n = 24). RESULTS: The median concentrations of activated HGFA in myeloma and control sera were 39.7 (range 6.2-450.0) and 17.6 ng/mL (range 4.8-280.6), respectively. The difference was statistically significant (P = 0.037). The median concentration of activated HGFA in bone marrow plasma was 6.1 ng/mL (range 3.5-30.0). CONCLUSION: We here show for the first time that the activated form of HGFA is present at high levels in serum and bone marrow of myeloma patients, thus providing a necessary prerequisite for the activation of HGF.

Prevention of thalidomide- and lenalidomide-associated thrombosis in myeloma.

The incidence of venous thromboembolism (VTE) is more than 1 per thousand annually in the general population and increases further in cancer patients. The risk of VTE is higher in multiple myeloma (MM) patients who receive thalidomide or lenalidomide, especially in combination with dexamethasone or chemotherapy. Various VTE prophylaxis strategies, such as low-molecular-weight heparin (LMWH), warfarin or aspirin, have been investigated in small, uncontrolled clinical studies. This manuscript summarizes the available evidence and recommends a prophylaxis strategy according to a risk-assessment model. Individual risk factors for thrombosis associated with thalidomide/lenalidomide-based therapy include age, history of VTE, central venous catheter, comorbidities (infections, diabetes, cardiac disease), immobilization, surgery and inherited thrombophilia. Myeloma-related risk factors include diagnosis and hyperviscosity. VTE is very high in patients who receive high-dose dexamethasone, doxorubicin or multiagent chemotherapy in combination with thalidomide or lenalidomide, but not with bortezomib. The panel recommends aspirin for patients with < or = 1 risk factor for VTE. LMWH (equivalent to enoxaparin 40 mg per day) is recommended for those with two or more individual/myeloma-related risk factors. LMWH is also recommended for all patients receiving concurrent high-dose dexamethasone or doxorubicin. Full-dose warfarin targeting a therapeutic INR of 2-3 is an alternative to LMWH, although there are limited data in the literature with this strategy. In the absence of clear data from randomized studies as a foundation for recommendations, many of the following proposed strategies are the results of common sense or derive from the extrapolation of data from many studies not specifically designed to answer these questions. Further investigation is needed to define the best VTE prophylaxis.

Identification of new targets for therapy of osteolytic bone disease in multiple myeloma.

One of the most characteristic features of multiple myeloma is the development of osteolytic bone lesions. Myeloma-associated bone disease is caused by an increase in osteoclastic bone resorption and a decrease in osteoblastic new bone formation. Insight into the molecular mechanisms of osteoclastogenesis has been provided by the detection of receptor activator of NF-kappaB ligand (RANKL), its specific receptor (RANK) and its decoy receptor antagonist osteoprotegerin (OPG). The RANK signaling system is abnormally regulated in multiple myeloma and targeting this system may ameliorate myeloma bone disease. Less is known about the development of osteoblastic dysfunction, and further knowledge about the interaction between myeloma cells and osteoblasts is required. The aim of this review is to focus on the principles of bone biology for a better understanding of the development of myeloma bone disease and to identify possible therapeutic targets.

Myocardial ischaemia and the inflammatory response: release of heat shock protein 70 after myocardial infarction.

OBJECTIVES: To test the hypothesis that heat shock protein (Hsp) 70 may be released into the circulation after acute myocardial infarction (AMI) by exploring the kinetics of Hsp70 release and the relations between Hsp70 and markers of inflammation and myocardial damage in AMI. DESIGN: Blood samples from 24 patients were prospectively collected through to the first day after AMI. Hsp70, interleukin (IL) 6, IL-8, and IL-10 in serum were measured by enzyme linked immunosorbent assay (ELISA). RESULTS: Median Hsp70 concentrations in AMI patients measured at arrival, six hours thereafter, and the following morning were 686, 868, and 607 pg/ml, respectively. These concentrations were all significantly different from those of the control patients with angina with a median serum Hsp70 concentration of 306 pg/ml. Peak Hsp70 correlated with creatine kinase (CK) MB (r = 0.62, p < 0.01) and cardiac troponin T (r = 0.58, p < 0.01). Furthermore, serum Hsp70 correlated with IL-6 and IL-8 at six hours (r = 0.60, p < 0.01 and r = 0.59, p < 0.01, respectively). CONCLUSIONS: In this study, Hsp70 was rapidly released into the circulation after AMI. Circulating Hsp70 is suggested as a marker of myocardial damage. In addition, Hsp70 may have a role in the inflammatory response after AMI.

Dual endoscopic-assisted endoluminal colostomy reversal: a feasibility study.

BACKGROUND: Emergent colostomies are associated with increased morbidity related to second closure operations. The purpose of this canine pilot study was to create a minimally invasive procedure that would reduce the time interval and morbidity involved with colostomy reversals after left colon end colostomies. METHODS: Six mongrel dogs underwent modified laparoscopic Hartmann's procedures in which the stapled end of the rectal stump was approximated to the left colon proximal to the stoma. After 1 week, they underwent an endoluminal colostomy reversal with a computer-mediated, circular stapling device and varying anvil insertion methods. Variables recorded included anvil insertion technique and feasibility, OR time, complications, and number of days to first meal and bowel movement. A contrast enema performed 1 week post colostomy reversal ruled out anastomosis leaks and stenosis. The dogs were euthanized and subjected to necropsy. RESULTS: Of four anvil insertion techniques tested, the most feasible employed a large-bore needle to perforate through the stapled end of the Hartmann pouch into the lumen of the left colon. Simultaneous endoluminal views of the rectal stump with a sigmoidoscope and the left colon lumen with an endoscope permitted a controlled and safe needle puncture. Through the needle, a guide wire was inserted to withdraw the anvil via the colostomy into place. A transanally inserted stapler was then married to the anvil under fluoroscopic guidance, thus completing the anastomosis. The colostomy was then taken down and transected at the level of the colocolostomy. Average operating time was 126 min (range 90-180), diet was tolerated within 1.5 days, and average number of days to first bowel movement was 2.5. The absence of stenosis, leaks, and inadvertent visceral injuries confirmed feasibility. CONCLUSIONS: In this canine model, a dual endoscopic-assisted colostomy reversal with a computer-mediated, circular stapling device is feasible. Using this technique, colostomy reversals can possibly be performed 1 week post-colostomy without entering the peritoneal cavity, thus reducing the number of invasive operations and subsequent morbidity required to manage emergent colon perforations.

Laparoscopic hand-assisted spleen autotransplantation.

BACKGROUND: Only recently has the spleen been perceived as an organ with a major immune function. This raised an interest in spleen salvage after spleen trauma and pancreatic tail resection, for the treatment of hematologic disorders and inducement tolerance for allogenic transplants. The purpose of this study was to evaluate the feasibility of a new technique for spleen transplantation: laparoscopic spleen autotransplantation in a large animal model. METHODS: Ten 35-kg pigs were used for this study. A laparoscopic hand-assisted splenectomy was first performed. The spleen was extracted through the handport to be flushed with a 4 degrees C saline solution and prepared extracorporeally. The graft was then reintroduced into the same animal's abdominal cavity, and a splenic-to-common iliac artery and vein bypass was performed laparoscopically using a 7-0 polytetrafluoroethylene running suture. The animal was killed 1 week postoperatively for histologic examination. RESULTS: All 10 animals tolerated the procedure well. No conversion to open surgery was required. The mean operative time was 253 +/- 45 min. The mean time needed to create the artery and vein anastomoses was 116 +/- 165 min, and the mean blood loss was 190 +/- 120 ml. There was no intra- or postoperative death. Intraoperative complications included two stenosed vascular anastomoses, which were taken down and revised. Seven of the 10 spleens were histologically viable 1 week after surgery. The nonviable transplantations were attributable to a thrombosis of the common iliac artery (n = 1) or the transplant artery (n = 2). CONCLUSIONS: Hand-assisted laparoscopic spleen autotransplantation is feasible in an animal model. This procedure could constitute an option when spleen resection is necessary for pancreatic tail resection, or when spleen preservation is important to the maintenance or restoration of an immune function.

Long-term results from laparoscopic common bile duct exploration.

BACKGROUND: The aim of this study was to evaluate the long-term results after laparoscopic common bile duct exploration (LCBDE). METHODS: A retrospective review of 175 consecutive patients who underwent attempted LCBDE between 1992 and 1999 was conducted. Laparoscopic transcystic exploration was accomplished in 110 patients and laparoscopic choledochotomy in 52 patients. Conversion to an open common bile duct exploration was required for 13 patients (7.4%). Retained common bile duct stones occurred in eight patients (4.6%). The 30-day postoperative morbidity was 6.9%, and there was no 30-day mortality. All the patients (alive and localized) received a questionnaire evaluating long-term results. RESULTS: Of the 175 patients, 169 (4 unrelated deaths and 2 patients lost to follow-up evaluation) received and 152 (90%) returned the questionnaire. The follow-up period ranged from 6 to 72 months (median, 36 months). One patient developed recurrent common bile duct stones. There were no signs or evidence of common bile duct stricture in any patient. CONCLUSION: The LCBDE procedure can be performed without increased risk of late bile duct complications.