Prognostic value of carbohydrate antigen 19-9 in patients undergoing resection of biliary tract cancer

Background: The clinical significance of abnormally high levels of carbohydrate antigen (CA) 19-9 after resection of biliary tract cancer (BTC) is not well established. The aim of this study was to determine the prognostic value of CA19-9 normalization in patients undergoing resection of BTC with curative intent. Methods: Patients with BTC undergoing resection with curative intent (1996–2015) were divided into those with normal preoperative CA19-9 level (normal CA19-9 group), those with an abnormally high preoperative CA19-9 level (over 37 units/ml) and normal postoperative CA19-9 level (normalization group), and those with an abnormally high preoperative CA19-9 level and abnormally high postoperative CA19-9 level (non-normalization group). Overall survival (OS) was analysed and predictors of OS were determined. Results: The normal CA19-9 group (180 patients) and normalization group (74) had better OS than the non-normalization group (58) (3-year OS rate 70·4, 73 and 31 per cent respectively; both P < 0·001). The normal CA19-9 and normalization groups had equivalent OS (P = 0·880). On multivariable analysis, factors associated with worse OS were lymph node metastases (hazard ratio (HR) 1·78; P = 0·014) and abnormally high postoperative CA19-9 level (HR 3·16; P < 0·001). In the normalization group, OS did not differ after R0 versus R1 resection (3-year OS rate 69 versus 62 per cent respectively; P = 0·372); in the non-normalization group, patients with R1 resection had worse OS (3-year OS rate 36 and 20 per cent for R0 and R1 respectively; P = 0·032). Conclusion: Non-normalization of CA19-9 level after resection of BTC with curative intent was associated with worse OS. R1 resection was associated with a particularly poor prognosis when CA19-9 levels did not normalize.