{"entity":{"id":"ca19-9","kind":"term","name":"CA 19-9","aka":[],"tldr":"A sugar molecule shed into the blood by most pancreatic cancers; useful to follow treatment, not to screen.","summary":"Sialyl-Lewis A carbohydrate antigen elevated in ~80% of PDAC; 5-10% of people (Lewis-negative) cannot make it. Prognostic at diagnosis, tracks response and recurrence, and defines eligibility in trials. Too non-specific for population screening (raised in biliary obstruction, pancreatitis), but glycan-engineered variants and combination with cfDNA are under study for high-risk surveillance.","asOf":"2026-09-06","wikipedia":"https://en.wikipedia.org/wiki/CA19-9","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/CA19-9"},{"label":"Ballehaninna and Chamberlain, J Gastrointest Oncol 2012: clinical utility of serum CA 19-9 in pancreatic adenocarcinoma","url":"https://doi.org/10.3978/j.issn.2078-6891.2011.021"},{"label":"Luo, Pancreatology 2018: CA19-9 in Lewis-negative patients with pancreatic cancer (1,482 patients)","url":"https://doi.org/10.1016/j.pan.2018.08.003"},{"label":"Isaji, Pancreatology 2018: international consensus on the definition and criteria of borderline resectable pancreatic cancer","url":"https://doi.org/10.1016/j.pan.2017.11.011"}],"tags":[],"related":[],"cancers":["pancreatic","ipmn-cystic-precursors","cholangiocarcinoma"],"sections":[],"technologies":["pancreatic-surveillance"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["lewis-negative","nccn-resectability-criteria-pancreatic"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":["paper-goonetilleke-ca19-9-systematic-review-ejso-2007","paper-hess-ca19-9-response-chemotherapy-lancet-oncol-2008","paper-tempero-ca19-9-lewis-antigens-cancer-res-1987","paper-yeh-ca19-9-lewis-negative-fut3-cutoff-ccr-2026","paper-fahrmann-ca19-9-lead-time-gastroenterology-2021"],"journals":[],"dependsOn":[],"notes":["In symptomatic patients CA 19-9 is 79 to 81 percent sensitive and 82 to 90 percent specific; as a screening test its positive predictive value is 0.5 to 0.9 percent; a level above 100 U/mL suggests unresectable or metastatic disease, and a fall of 20 to 50 percent or normalisation after surgery or chemotherapy predicts longer survival (Ballehaninna 2012).","A CA 19-9 above 500 U/mL makes an anatomically resectable tumour biologically borderline resectable in the 2017 international consensus (Isaji 2018). Not every Lewis-negative patient is a non-secretor: 27.4 percent of Lewis-negative patients in a 1,482-patient series still had a raised level (Luo 2018).","Pancreatic ductal adenocarcinoma: pooled sensitivity 79% and specificity 82% across 2,283 patients, with cholestasis raising it falsely (Goonetilleke 2007). Baseline level is prognostic (5.8 against 10.3 months above the median) but a 50% fall on chemotherapy is not a valid surrogate for survival once guarantee-time bias is corrected (Hess 2008). About 10% of patients are Lewis-negative (FUT3-null) and cannot make it at all, with median 2.4 against 496 U/mL and survival as poor as the highest-marker group; 7 U/mL or below identifies them with 95% positive predictive value (Tempero 1987, Yeh 2026). Levels rise about two years before diagnosis, reaching 60% sensitivity only in the last six months (Fahrmann 2021)."],"category":"Biomarkers"},"route":"/terms/ca19-9/","neighbours":{"cancer":[{"id":"ampullary","kind":"cancer","name":"Ampullary cancer (ampulla of Vater)","route":"/cancers/ampullary/"},{"id":"cholangiocarcinoma","kind":"cancer","name":"Biliary tract cancer (cholangiocarcinoma)","route":"/cancers/cholangiocarcinoma/"},{"id":"borderline-resectable-pdac","kind":"cancer","name":"Borderline resectable pancreatic ductal adenocarcinoma","route":"/cancers/borderline-resectable-pdac/"},{"id":"extrahepatic-cholangiocarcinoma","kind":"cancer","name":"Extrahepatic cholangiocarcinoma (perihilar and distal)","route":"/cancers/extrahepatic-cholangiocarcinoma/"},{"id":"gallbladder","kind":"cancer","name":"Gallbladder cancer","route":"/cancers/gallbladder/"},{"id":"ipmn-cystic-precursors","kind":"cancer","name":"Intraductal papillary mucinous neoplasm and other pancreatic cystic precursors","route":"/cancers/ipmn-cystic-precursors/"},{"id":"kras-g12c-pdac","kind":"cancer","name":"KRAS G12C-mutant pancreatic ductal adenocarcinoma","route":"/cancers/kras-g12c-pdac/"},{"id":"locally-advanced-pdac","kind":"cancer","name":"Locally advanced unresectable pancreatic ductal adenocarcinoma","route":"/cancers/locally-advanced-pdac/"},{"id":"metastatic-pdac","kind":"cancer","name":"Metastatic pancreatic ductal adenocarcinoma","route":"/cancers/metastatic-pdac/"},{"id":"pancreatic","kind":"cancer","name":"Pancreatic ductal adenocarcinoma","route":"/cancers/pancreatic/"},{"id":"resectable-pdac","kind":"cancer","name":"Resectable pancreatic ductal adenocarcinoma","route":"/cancers/resectable-pdac/"}],"technology":[{"id":"pancreatic-surveillance","kind":"technology","name":"High-risk pancreatic surveillance (CAPS / PRECEDE)","route":"/technologies/pancreatic-surveillance/"},{"id":"serum-tumour-markers","kind":"technology","name":"Serum tumour markers: proper use and misuse","route":"/technologies/serum-tumour-markers/"}],"term":[{"id":"pancreatic-cyst-high-risk-stigmata","kind":"term","name":"High-risk stigmata and worrisome features of pancreatic cysts (IPMN and MCN surgical criteria)","route":"/terms/pancreatic-cyst-high-risk-stigmata/"},{"id":"lewis-negative","kind":"term","name":"Lewis-negative (Lewis antigen-negative, CA 19-9 non-secretor) status","route":"/terms/lewis-negative/"},{"id":"new-onset-diabetes-pancreatic-cancer","kind":"term","name":"New-onset diabetes as a signal of pancreatic cancer (and the ENDPAC score)","route":"/terms/new-onset-diabetes-pancreatic-cancer/"},{"id":"nccn-resectability-criteria-pancreatic","kind":"term","name":"Resectability classes for pancreatic cancer (NCCN anatomical criteria and the 2017 international consensus)","route":"/terms/nccn-resectability-criteria-pancreatic/"}],"paper":[{"id":"paper-yeh-ca19-9-lewis-negative-fut3-cutoff-ccr-2026","kind":"paper","name":"A new CA19-9 cutoff value identifies Lewis antigen status and refines prognostic stratification in PDAC","route":"/key-papers/paper-yeh-ca19-9-lewis-negative-fut3-cutoff-ccr-2026/"},{"id":"paper-hess-ca19-9-response-chemotherapy-lancet-oncol-2008","kind":"paper","name":"CA 19-9 tumour-marker response to chemotherapy in patients with advanced pancreatic cancer enrolled in a randomised controlled trial","route":"/key-papers/paper-hess-ca19-9-response-chemotherapy-lancet-oncol-2008/"},{"id":"paper-cohen-ctdna-protein-liquid-biopsy-pancreatic-pnas-2017","kind":"paper","name":"Combined circulating tumor DNA and protein biomarker-based liquid biopsy for the earlier detection of pancreatic cancers","route":"/key-papers/paper-cohen-ctdna-protein-liquid-biopsy-pancreatic-pnas-2017/"},{"id":"paper-fahrmann-ca19-9-lead-time-gastroenterology-2021","kind":"paper","name":"Lead-Time Trajectory of CA19-9 as an Anchor Marker for Pancreatic Cancer Early Detection","route":"/key-papers/paper-fahrmann-ca19-9-lead-time-gastroenterology-2021/"},{"id":"paper-worthington-precede-early-detection-biomarkers-ijc-2026","kind":"paper","name":"Pancreatic cancer early detection biomarkers for high-risk individuals: insights from the PRECEDE consortium","route":"/key-papers/paper-worthington-precede-early-detection-biomarkers-ijc-2026/"},{"id":"paper-malla-ctdna-resected-biliary-tract-cancer-esmo-gi-onc-2026","kind":"paper","name":"Real-world analysis of ctDNA and other biomarkers in patients with curatively resected stage I-III biliary tract cancer","route":"/key-papers/paper-malla-ctdna-resected-biliary-tract-cancer-esmo-gi-onc-2026/"},{"id":"paper-tempero-ca19-9-lewis-antigens-cancer-res-1987","kind":"paper","name":"Relationship of carbohydrate antigen 19-9 and Lewis antigens in pancreatic cancer","route":"/key-papers/paper-tempero-ca19-9-lewis-antigens-cancer-res-1987/"},{"id":"paper-goonetilleke-ca19-9-systematic-review-ejso-2007","kind":"paper","name":"Systematic review of carbohydrate antigen (CA 19-9) as a biochemical marker in the diagnosis of pancreatic cancer","route":"/key-papers/paper-goonetilleke-ca19-9-systematic-review-ejso-2007/"}],"idea":[{"id":"idea-mced-new-onset-diabetes","kind":"idea","name":"Blood-based pancreatic cancer detection in new-onset diabetes","route":"/ideas/idea-mced-new-onset-diabetes/"},{"id":"idea-pdac-new-onset-diabetes-risk-score-pathway","kind":"idea","name":"Run the ENDPAC score on every new diabetes diagnosis after 50 and scan the high scorers","route":"/ideas/idea-pdac-new-onset-diabetes-risk-score-pathway/"}],"roadmap":[{"id":"pancreatic-roadmap","kind":"roadmap","name":"Pancreatic cancer roadmap: from Whipple's operation to gemcitabine, FOLFIRINOX, adjuvant chemotherapy, PARP inhibition, KRAS inhibition, vaccines and the surveillance question","route":"/roadmaps/pancreatic-roadmap/"}],"trial":[{"id":"mpact","kind":"trial","name":"MPACT","route":"/trials/mpact/"},{"id":"panfire-2","kind":"trial","name":"PANFIRE-2","route":"/trials/panfire-2/"},{"id":"scalop","kind":"trial","name":"SCALOP","route":"/trials/scalop/"}],"bottleneck":[{"id":"b-early-detection","kind":"bottleneck","name":"The hardest cancers are found late","route":"/bottlenecks/b-early-detection/"}]}}