You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
Local staging of pancreatic cancer: criteria for unresectability of major vessels as revealed by pancreatic-phase, thin-section helical CT.
Abstract 1:
OBJECTIVE This study was conducted to determine the criteria for unresectability of major peripancreatic vessels in patients with pancreatic carcinoma as revealed by optimally enhanced , pancreatic-phase thin-section helical CT . SUBJECTS AND METHODS Twenty-five patients with pancreatic adenocarcinoma who underwent local dissection during curative or palliative surgery also underwent preoperative pancreatic-phase thin-section helical CT  ( 40- to 70-sec delay , 2.5- to 3-mm collimation ) . Tumor involvement of the portal and superior mesenteric veins and the celiac , hepatic , and superior mesenteric arteries was prospect ively grade d on a 0 - 4 scale based on circumferential contiguity of tumor to vessel . Subsequent surgical results were then correlated with the CT grade s. RESULTS At surgery , definitive evaluation was possible for 80 vessels . Forty-eight of 48 vessels grade d 0 and three of three vessels grade d 1 were resectable . Four of seven vessels grade d 2 , seven of eight vessels grade d 3 , and 14 of 14 vessels grade d 4 were unresectable . A threshold of between grade s 2 and 3 , which corresponded to tumor involvement of one-half circumference of the vessel , yielded the lowest number of false-negatives and an acceptable number of false-positives for unresectability . Such a threshold would have yielded a sensitivity of 84 % , a specificity of 98 % , a positive predictive value of 95 % , and a negative predictive value of 93 % for unresectability of the vessels studied . CONCLUSION A grading system for tumor involvement of the major vessels in patients with pancreatic adenocarcinoma can be based on the degree of circumferential contiguity of tumor to vessel . Involvement of vessel to tumor that exceeds one-half circumference of the vessel is highly specific for unresectable tumor


Title 2:
Role of three-dimensional imaging in operative planning for hilar cholangiocarcinoma.
Abstract 2:
BACKGROUND Complex , highly variable , anatomic relationships in the portal hilum complicate the surgical management at hilar cholangiocarcinoma . Preoperative three-dimensional ( 3D ) imaging to stage the tumor and define anatomy may help in planning for curative resection . METHODS Between 2003 and 2006 , 20 consecutive patients with hilar cholangiocarcinoma underwent preoperative multidetector row computed tomography ( MDCT ) cholangiography ;  3D images of the portal vein , hepatic artery , and bile ducts were created and viewed simultaneously . Longitudinal tumor extension was evaluated by direct cholangiography and 3D cholangiography , and contiguous spread by 2D computed tomography ( CT ) .  Of 20 patients , 15 underwent surgical resection . Liver resection was planned based on 3D imaging that allowed visualization of the relationship between the tumor and the umbilical portion of the left portal vein , or the bifurcation of the anterior and posterior branch of the right portal vein . Preoperative and operative findings were compared . RESULTS All patients tolerated  3D CT without serious complication . The accuracy rates of longitudinal tumor extension , using the Bismuth-Corlette classification system , were 85 % ( 11/13 ) and 87 % ( 13/15 ) with direct cholangiography and 3D cholangiography , respectively . The sensitivity , specificity , and accuracy rates were 100 % , 80 % , and 87 % for portal invasion and 75 % , 91 % , and 87 % for hepatic arterial invasion . The number of bile duct orifices in the cut end of the hilar plate was estimated correctly in 13 of 15 patients . There were no operative deaths . Potentially curative resection was achieved in 14 of 15 patients . CONCLUSIONS 3D images provide accurate information about the relationship between hilar cholangiocarcinoma and adjacent vessels . This technique is a powerful new tool for improving the proportion of potentially curative resection


Title 3:
Staging of hilar cholangiocarcinoma by ultrasound and duplex sonography: a comparison with angiography and operative findings.
Abstract 3:
The pre-operative radiological assessment of proximal bile duct tumours is clinical ly important as resection may be limited by tumour extension along the bile ducts , into hepatic parenchyma or the adjacent vascular structures . Demonstration of the extent of biliary and vascular involvement can direct additional investigations and definitive treatment . 22 patients with hilar cholangiocarcinoma were studied pre-operatively by conventional ultrasound ( US ) and duplex sonography ( DS ) . The extent of tumour infiltration and vascular involvement was compared with arteriography and operative findings . Bile duct dilatation and the level of obstruction was documented by US in 22 ( 100 % ) , and the tumour was shown by US in 19 ( 86 % ) . In these 19 patients , the extent of extraductal extension compared with operative findings was correct in 13 , underestimated in two , and in four infiltration was massed . Vascular patency or involvement was correctly determined by DS in 19 ( 86 % ) , and by arteriography in 18 ( 82 % ) . In two of the three incorrect DS interpretations , lobar atrophy and contralateral hypertrophy distorted the hilar anatomy . US with DS is valuable in the pre-operative staging of proximal bile duct tumours in predicting ductal and vascular involvement


Title 4:
Preoperative assessment and staging of hilar cholangiocarcinoma with 16-multidetector computed tomography cholangiography and angiography.
Abstract 4:
BACKGROUND / AIMS To evaluate prospect ively the preoperative use of 16-multidetector computed tomography ( MDCT ) with cholangiography and angiography in determining the resectability of hilar cholangiocarcinoma . METHODOLOGY From January 2002 to January 2008 , 75 consecutive patients with hilar cholangiocarcinoma underwent preoperative MDCT with cholangiography and angiography .  3D images of the portal vein , hepatic artery , and bile ducts were created and viewed simultaneously . The accuracy of MDCT with cholangiography and angiography was determined by comparison with intraoperative and pathologic findings . RESULTS All patients tolerated the CT imaging well and without serious complication . The sensitivity , specificity , and accuracy rates were 92.9 % , 100 % , and 96 % for portal vein invasion and 83.3 % , 100 % , and 93.3 % for hepatic arterial invasion . The accuracy rate of longitudinal tumor extension , using the modified Bismuth-Corlette classification , was 96 % . The sensitivity , specificity , and accuracy of prediction of resectability were 95.7 % , 82.1 % , and 90.7 % , respectively . CONCLUSIONS Preoperative MDCT with cholangiography and angiography gave a good assessment of the degree of biliary and vascular involvement of hilar cholangiocarcinoma . It also accurately predicted resectability


Title 5:
Preoperative assessment of hilar cholangiocarcinoma by dual-modality PET/CT.
Abstract 5:
BACKGROUND The purpose of the current study was to evaluate the accuracy of (18)F-FDG PET/CT in staging hilar cholangiocarcinoma . MATERIAL S AND METHODS From June 2004 to December 2007 , patients evaluated for surgical treatment of hilar cholangiocarcinoma were entered into a prospect i ve data base . Dual modality (18)F-FDG PET/CT was performed before surgery . The report was review ed with comparison to the operative and pathological results in each case for tumour-node-metastasis staging . RESULTS Seventeen patients ( 6 women , 11 men ) of a median age of 62 years were included in the study . Radical tumour resection was performed on seven patients . Ten patients underwent surgical exploration . The sensitivity of PET/CT  in detecting primary tumour was found to be 58.8 % ( 25 % in T2 tumour , 70 % in T3 tumour , 66.7 % in T4 tumour ) . The sensitivity/specificity of PET/CT in detecting lymph node metastasis and distant metastasis were 41.7%/80 % and 55.6%/87.5 % , respectively . Positive (18)F-FDG uptake in the bile duct was found to be associated with surgical non-resectability ( P = 0.05 ) . CONCLUSION Dual-modality PET/CT imaging was found to have a high specificity in detection of lymph node and distant metastasis in hilar cholangiocarcinoma , with a limited value in correct judgement of surgical resectability for tumours in stadium UICC I-III
Data primarily concern CT , which has an acceptable accuracy for assessment of ductal extent , portal vein and hepatic artery involvement , but low sensitivity for nodal status