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CA19-9 Response Pancreas — SCE Medical Oncology MCQ

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ModerateGI CancersCA19-9 Response PancreasSCE Medical Oncology

A 55-year-old man with pancreatic cancer has CA19-9 of 850 U/mL at diagnosis. After 3 months of FOLFIRINOX, CA19-9 drops to 85 U/mL. CT shows a partial response. What does CA19-9 response predict?

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Correct answer: A — >50% decline in CA19-9 during treatment correlates with better radiographic response, resectability and survival — CA19-9 kinetics complement imaging for treatment response assessment in pancreatic cancer

CA19-9 is the most clinically useful biomarker in pancreatic cancer. A >50% decline from baseline during treatment correlates with objective radiographic response and improved OS. CA19-9 normalisation (<37 U/mL) is associated with the best outcomes. Important caveats: ~5-10% of patients are Lewis-antigen-negative and cannot produce CA19-9 (false-negative); biliary obstruction falsely elevates CA19-9 (must resolve obstruction before using as a tumour marker). CA19-9 kinetics complement imaging for response assessment and guide surgical re-evaluation in borderline resectable disease.

Reference: ESMO 2024 Pancreatic Cancer; NICE NG85; Boeck et al JCO 2006