This subset is enriched in ICC, where SPP1+ TAN abundance correlates with serum carbohydrate antigen 19-9 (CA19-9) levels (r = 0.62, p = 0.003) and increased postoperative recurrence risk ([HR] = 1.8, p = 0.02), consistent with ICC’s poor prognosis (21, 135). Here, SPP1 is linked to intrahepatic cholangiocarcinoma.