Nodal areas of potential geographic error in adjuvant radiotherapy for biliary tract cancer

Purpose: To determine the areas of potential geographic error in adjuvant radiotherapy (RT) for biliary-tract cancer (BTC) by comparing pathological-surgical data on the pattern of nodal spread with the extent of elective nodal CTV used in published RT studies in this setting. Material/methods: A literature search was performed to select articles an: 1/adjuvant RT for BTC, that provided information on the lymph node stations (LNS) included in the CTV; 2/the pathological-surgical data on the patterns of nodal involvement/recurrence in BTC. Risk of nodal involvement/recurrence and frequency of inclusion in the CTV in RT studies for each of the LNS were compared to determine the areas of potential geographic misses and unnecessary irradiation, separately for intrahepatic cholangiocarcinoma (IHC), extrahepatic cholangiocarcinoma (EHC) and gallbladder-cancer (GBC). Results: Areas of potential geographic misses include: for right IHC: paraaortic and superior mesenteric artery (SMA) LNS; for left or hilar IHC: left gastric, lesser gastric curvature, paraaortic, and SMA LNS; for proximal EHC: paraaortic LNS; for middle EHC: paraaortic and SMA LNS; for distal EHC: paraaortic, SMA, and anterior pancreatico-duodenal LNS; for GBC: paraaortic, SMA, and posterior pancreaticoduodenal LNS. Celiac-LNS is unnecessarily irradiated for middle/distal EHC. Conclusions: In view of discrepancies between pathological-surgical data and the CTVs used in common practice, there is an obvious need for international consensus guidelines. (C) 2017 Elsevier B.V. All rights reserved.