Tumor markers - Measurable molecules that are associated with a malignancy.
Tumor-derived - produced by tumor cells OR
Tumor-associated – produced by the body in response to tumor.
May be in circulation or tissue bound.
Although there are a multitude of tumor markers, very few of them have found their way into clinical practice because of their lack of specificity. However, some of these non-specific markers have found a place in monitoring cancer treatment rather than in diagnosis.
Mean specificity – 90%, sensitivity – 81%, using a cut-off point of 37 IU/ml
May be raised in other conditions – other advanced cancers, non-neoplastic conditions including pancreatitis, cholangitis and hepatocellular jaundice
In presence of jaundice – specificity becomes lesser
Of limited value in diagnosing pancreatic cancer, esp. early cases – can complement radiologic procedures, especially in non-jaundiced pts.; only 55% of patients with tumors <3 cm in size have ↑ CA 19-9.