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Cancer Antigen 19-9

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Cancer Antigen 19-9, CA 19-9

  • See Also
  1. Pancreatic Cancer
  • 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
  • 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)
  • Causes
  • Increased CA 19-9
  1. Pancreatic Ductal Adenocarcinoma
  2. Chronic Pancreatitis
  3. Non-cancerous bile tract disease
  4. Chronic inflammatory states
  1. False Negatives in 10% of population that fails to synthesize CA 19-9
  • 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]
  • References
  1. Safi (1987) Pancreas 2(4): 398-403 [PubMed]
  2. Zhao (2022) Eur J Gastroenterol Hepatol 34(9): 891-904 [PubMed]
  3. Goonetilleke (2007) Eur J Surg Oncol 33(3):266-70 +PMID: 17097848 [PubMed]