To investigate potential confounders influencing CEACAM6 levels we identified four potential populations that could be expected to have different degrees of secretion: 1) Biliary obstruction (Elevated total bilirubin, elevated alkaline phosphatase, stented, or bile salt concentration below benign median) 2) Advanced age (age over 65) 3) Gender 4) Elevation in standard tumor marker (CA19-9 elevation). The gene discussed is CEACAM6; the disease is neoplasm.