There have been significant advances in the understanding of pancreatic cancer at the molecular level and in the treatment of early-stage tumors. A blood test for pancreatic cancer is possible by measurement of serum CA 19-9, which can be a useful biomarker for the disease.
Pancreatic Cancer Facts
Pancreatic cancer is the fourth highest cause of cancer-related death inthe USA. Less than 20% of patients present with disease that is curable and the average 5-year survival rate is below 5%.
Environmental risk factors for pancreatic cancer include smoking and high fat diets. Some studies show an increased incidence of pancreaticcancer among patients with a history of diabetes, chronicpancreatitis or chronic cirrhosis.
- Pancreatic cancer results from the accumulation of successive genetic mutations. Pre-malignant lesions develop in the ductal epithelium and develop into invasive disease.
Clinical Signs and Symptoms of Pancreatic Cancer
Symptoms of pancreatic cancer depend on the locationof the tumor within the gland and the stage of thedisease, but generally include:
- obstructive cholestasis.
abdominaldiscomfort and nausea.
- pancreatitis (inflammation of the pancreas)
abnormal blood glucose levels
anorexia and weight loss.
- temporal wasting
- peripheral lymphadenopathy
- hepatomegaly and ascites.
Diagnostic Procedures for Pancreatic Cancer
- Routine blood tests: may detect mild abnormalities in liver-function, hyperglycemia, anemia and increased insulin levels.
Computed tomography (CT): this allows visualizationof the primary tumor.
Endoscopicultrasonography: can be useful in patients where a pancreatic tumoris suspected but there is no visible massfrom CT. It allows tissue to be obtained for microscopic analysis.
A Blood Test for Pancreatic Cancer: CA 19-9
There are numerous potential serum biomarkers for diagnosis of pancreatic cancer but so far, the tumor-associated antigen CA 19-9 is the only one considered clinically useful.
CA 19-9 is a serum carbohydrate antigen. Serum levels rise in pancreatic cancer patients due to increased secretion of the antigen from malignant cells.
CA 19-9 isused for therapeutic monitoring and for early detection of recurrentdisease after treatment. Elevated levels of CA 19-9 correlate with tumour differentiation and the extent of disease. Preoperative CA 19-9 levels below 200 U/ml and normalisation after treatment has been associated with a longer disease-free survival. Elevation of serum CA 19-9 levels can be a good predictor of tumour recurrence.
Limitations of the CA 19-9 Blood Test for Pancreatic Cancer
- CA 19-9 is a sialyted Lewis blood group antigen. People who lack the Lewis antigen glycosyltransferase are unable to synthesise CA 19-9 (around 10% of the population). In this group of patients the level of CA 19-9 can be normal, even in advanced disease.
CA 19-9 may be elevated in other conditions such as cholestasis.
- The sensitivity of the CA 19-9 test is variable. Up to 30% of pancreatic cancer patients do not have elevated CA 19-9.
- Raised CA 19-9 can occur in benign inflammatory diseases of the pancreatobiliary tract.
- Due to lower levels of CA 19-9 in localised pancreatic cancer, it is not useful as a marker of early disease.
Pancreatic Cancer. M.Hidalgo. New England Journal of Medicine, April 2010,Vol 362 P1605-1617
Molecular Markers of Pancreatic Cancer: Development and Clinical Relevance. L.Fry, K.Mönkemüller&P.Malfertheiner, Langenbeck's Archives of Surgery, 2008, Vol 393, P883-90