Serum-Based Immunoassay May Detect Pancreatic Cancer Early
San Francisco, CA—A serum-based enzyme immunoassay using the PAM4 antibody, combined with the serum marker CA19-9, detected stage I pancreatic cancer in nearly two thirds of patients analyzed in a study presented at the 2012 Gastrointestinal Cancers Symposium. It also demonstrated high discriminatory power with respect to benign pancreatitis.
“The PAM4-based assay to quantify antigen in patients’ sera shows high sensitivity and specificity for the detection of pancreatic ductal adenocarcinoma (PDAC),” said David V. Gold, PhD, Director of Laboratory Administration, Garden State Cancer Center, Morris Plains, NJ.
“The results provide a basis for future studies of a combined PAM4 plus CA19-9 biomarker analysis for surveillance of patients at high risk for the development of PDAC, which makes up approximately 90% of all pancreatic cancers, and is highly lethal,” Dr Gold said.
Certain populations of patients, including persons with a family history of pancreatic cancer, are considered at risk for the disease.
The assay was evaluated in more than 600 tissue specimens, including 234 with PDAC. Combining PAM4 with CA19-9 led to greater sensitivity, while maintaining a high level of specificity.
When used individually, PAM4 detected 74% of positive PDAC cases and CA19-9 detected 77%, but combined they detected 84%, a significant (P < .001) improvement over the single tests.
For patients at high risk for PDAC, long-term follow-up for the PAM4-positive patients may help detect early PDAC, Dr Gold said. “The combined use of PAM4 and CA19-9 biomarkers gave enhanced detection of PDAC versus either alone and…achieved high specificity.”
Low False-Positive Rate
The specificity of PAM4 was significantly greater than that of CA19-9, which detected more than twice as many benign conditions (ie, chronic pancreatitis). Combined, of 50 cases of chronic pancreatitis, 9 (18%) were labeled positive by the assay, but that 18% rate of positivity does not represent “false-positives,” Dr Gold said.
The investigators examined 32 chronic pancreatitis specimens and identified 10 preneoplastic lesions. PAM4 reacted with these lesions but not with the completely benign, nonneoplastic tissue.
“Our results indicate that PAM4 is not reactive with inflamed pancreatic tissue but rather [with] neoplastic tissue that develops within the inflamed chronic pancreatitis parenchyma,” he concluded. “We speculate that chronic pancreatitis patients, and perhaps others having disease that places them at high risk for the development of PDAC, who are PAM4-positive, may harbor occult PDAC or have significant numbers of precursor lesions producing the PAM4 biomarker.”—CH