II. Pathophysiology

  1. Cancer Antigen 19-9 is expressed in pancreatic disease and hepatobiliary disease
  2. CA 19-9 is a soluble, fucosylated glycosphingolipid CarbohydrateAntigen
  3. Structurally related to the Lewis Blood Group Antigens

III. Indications

  1. Pancreatic ductal adenocarcinoma
    1. Confirms diagnosis when consistent with other findings (see other False Positive causes below)
    2. Predicts prognosis as well as recurrence risk
      1. CA 19-9 level reduction by at least 50% after treatment is associated with a better prognosis
      2. Ye (2020) Cancer Chemother Pharmacol 86(6):731-40 +PMID: 33047181 [PubMed]
  2. Not indicated for screening in asymptomatic patients
    1. No tumor specific (see efficacy below)

IV. Causes: Increased CA 19-9

  1. Pancreatic Ductal Adenocarcinoma
  2. Chronic Pancreatitis
  3. Non-cancerous bile tract disease
  4. Chronic inflammatory states

V. Causes: False Negative

  1. False Negatives in 10% of population that fails to synthesize CA 19-9

VI. Efficacy: Pancreatic Ductal Adenocarcinoma Diagnosis

  1. CA 19-9 Level >37 U/ml
    1. Test Sensitivity: 72% (some studies have shown test sensitivities as low as 50%)
    2. Test Specificity: 86%
    3. Negative Likelihood Ratio (LR-): 0.32
    4. Positive Likelihood Ratio (LR+): 5.1
  2. High False Positive Rate in asymptomatic patients (do not use for screening)
    1. Kim (2004) J Gastroenterol Hepatol 19(2): 182-6 [PubMed]

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