Proposal for a new classification for perihilar cholangiocarcinoma based on tumour depth

Abstract

Background: The T system for distal cholangiocarcinoma has been revised from a layer-based to a depth-based approach in the current American Joint Committee on Cancer (AJCC) classification. In perihilar cholangiocarcinoma, tumour depth in the staging scheme has not yet been addressed. The aim of this study was to propose a new T system using measured tumour depth in perihilar cholangiocarcinoma.Methods: Patients who underwent hepatectomy for perihilar cholangiocarcinoma between 2001 and 2014 were reviewed retrospectively. The vertical distance between the top of the tumour and deepest invasive cells was measured as invasive tumour thickness (ITT) by two independent pathologists. Log rank statistics were used to determine cut-off points, and the concordance (C) index was used to assess survival discrimination of each T system. Results: ITT was measurable in all 440 patients, with a median value of 6⋅0 (range 0-45) mm. The median difference in ITT between observers was 0⋅6 (range 0-20) mm. Cut-off points for prognosis were 1, 5 and 8 mm. Five-year survival decreased with increasing ITT (P < 0⋅001): 67 per cent for ITT less than 1 mm (25 patients), 54⋅9 per cent for ITT 1 mm and over to less than 5 mm (138 patients), 43⋅4 per cent for ITT 5 mm and over to less than 8 mm (118 patients), and 32⋅2 per cent for ITT 8 mm and over (159 patients). The C-index of this classification was comparable to that of the current AJCC T classification (0⋅598 versus 0⋅589).Conclusion: ITT is a reliable approach for making a depth assessment in perihilar cholangiocarcinoma. A four-tier ITT classification with cut-off points of 1, 5 and 8 mm is an adequate alternative to the current layer-based T classification.

The 8th Edition American Joint Committee on Cancer Staging for Hepato-pancreato-biliary Cancer: A Review and Update

“…One proposal is to follow the same staging algorithm as that for the distal common bile duct, where a depth-based rather than layer-based measurement is applied to define T stage. 31 Using a 4-tier invasive tumor thickness with cutoff points of 1, 5, and 8 mm, these new defining parameters appear to be an adequate alternative, improving the concordance index from 0.589 to 0.598. 31 Other proposals include incorporating more biological factors such as microvascular invasion, perineural invasion, and tumor differentiation to ensure a personalized approach for prognostication and treatment.…”

“…31 Using a 4-tier invasive tumor thickness with cutoff points of 1, 5, and 8 mm, these new defining parameters appear to be an adequate alternative, improving the concordance index from 0.589 to 0.598. 31 Other proposals include incorporating more biological factors such as microvascular invasion, perineural invasion, and tumor differentiation to ensure a personalized approach for prognostication and treatment. 32 In contrast to the T category, the new N category in the 8th edition appeared to perform better than that in the previous edition.…”

Survival analysis of patients with stage T2a and T2b perihilar cholangiocarcinoma treated with radical resection

“…While other investigators have noted its accuracy [ 18 , 19 ]. Some researchers had proposed to change the T staging of pCCA [ 20 , 21 ]. Currently, both the T2aN0M0 and T2bN0M0 are classified as TNM stage II in the 7th and 8th edition of AJCC staging system.…”

Survival analysis of patients with stage T2a and T2b perihilar cholangiocarcinoma treated with radical resection

“…[18,19] Some researchers had proposed to change the T staging of pCCA. [20,21] Currently, both the T2aN0M0 and T2bN0M0 are classi ed as TNM stage in the 7th and 8th edition of AJCC staging system. However, in clinical practice, hemihepatectomy with resection of caudate lobe as well as an extrahepatic bile duct resection was compulsory in most surgical plans except for Bismuth type I.…”