The present disclosure relates to a method for treating biliary tract cancer in a subject by inhibiting tenascin W by administering to said subject a therapeutically effective amount of a modulator of said tenascin, for example a specific antibody or a siRNA. The present disclosure also encompasses methods of diagnosing cancer by measuring levels of tenascin-W, as well as method of targeted therapy using anti-tenascin-W antibodies conjugated to therapeutic agents.
