August 8, 2011 — A screening protocol that uses serum levels of CA 19-9 to guide the use of endoscopic ultrasound (EUS) can identify early-stage pancreatic cancer, and is more likely to do so than standard means of detection, according to research published in the July issue of Gastrointestinal Endoscopy.
"By adhering to this protocol, you are significantly more likely to detect early stage 1 pancreatic cancers than if you use normal means — that's the take-home message," lead author Richard Zubarik, MD, chief of endoscopy at Fletcher Allen Health Care, University of Vermont, Burlington, told Medscape Medical News.
But other experts are not so sure.
"The authors rightly conclude that their study demonstrates the feasibility of such an approach, but we need to see validation in larger trials involving more patients," Wen Wee Ma, MD, from the Roswell Park Cancer Institute, Buffalo, New York, told Medscape Medical News.
Another expert, Randall E. Brand, MD, professor of medicine at the University of Pittsburgh Medical Center in Pennsylvania, agrees that the concept merits more study. "This was not the best-designed study," he told Medscape Medical News. "To me, the take-home message was more that this is very provocative, very suggestive, but needs a better study to really expand on the results. It's hard for me to take a lot out of this study."
Earlier Detection of Pancreatic Cancer Is Needed
In their study, Dr. Zubarik and colleagues performed a serum CA 19-9 test on 546 patients, aged 50 to 80 years, who had at least 1 first-degree relative with pancreatic adenocarcinoma.
"The sensitivity and specificity of this tumor marker ... are reported to range from 70% to 90% and 70% to 98%, respectively," Dr. Zubarik said. "This blood test has been used in the past to follow people with pancreatic cancer in mass screening, but has never been used in this high-risk population before."
If the CA 19-9 test was above 37 U/mL, the individual went on to have EUS.
Any lesions that were detected in the pancreas were biopsied.
"The pancreas lies right behind the stomach and the first part of the small intestine. You get a very fine look at it with that test, and with ultrasound guidance, you can biopsy as many lesions as you see," Dr. Zubarik explained.
CA 19-9 serum levels were above 37 U/mL in 27 patients (4.9%). EUS was performed in 26 patients (1 patient refused to undergo the procedure).
The EUS findings were normal in 14 patients.
Potentially premalignant or malignant findings were detected in 5 patients (0.9%). Of these, 1 patient was diagnosed with stage 1 adenocarcinoma.
In addition to the adenocarcinoma, the screening protocol detected 1 neuroendocrine tumor, 1 intraductal papillary mucinous neoplasm, 1 mucinous neoplasm, and 1 pancreatic intraepithelial neoplasia-1.
The patient with adenocarcinoma had surgery and is alive and well 3.5 years later, with a CA 19-9 level of 11 and no evidence of disease recurrence. All other patients with neoplasia are also alive and well, Dr. Zubarik noted.
The patient diagnosed with stage 1 adenocarcinoma "is the longest survivor of pancreatic adenocarcinoma detected in a published screening protocol," he said.
The cost to detect 1 pancreatic neoplastic lesion was $8,430.75. The cost to detect the single adenocarcinoma was $41,123.74.
"I am pleased with the results," Dr. Zubarik said. "The findings are preliminary. It's an exciting idea that I think needs to be further evaluated to see if it's cost effective."
Not Ready for Prime Time
However, Dr. Ma suggested that this screening protocol is problematic in several ways.
Only 70% to 80% of pancreatic cancer patients express CA 19-9, so this approach will not pick up the other 30% who have pancreatic cancer but do not express this biomarker, he pointed out. "We need a better, more specific serum biomarker for pancreatic cancer screening than CA 19-9."
In addition, EUS fine-needle aspiration (FNA) is highly complex, operator-dependent, and requires specialized expertise. "The centers that can do good, safe EUS FNA of the pancreas are often confined to tertiary centers, posing a limitation to large-scale screening," he said.
Dr. Ma also pointed out that, in the study, the detection rate in this high-risk population for pancreatic adenocarcinoma was 0.2%, with a false-positive rate of 0.9%.
The article also failed to discuss complications from blood draws and EUS FNA procedures. "Risks of bowel perforation, bleeding, need for anesthesia, etc., with EUS FNA need to be taken into account, since these are significant factors," he said. "I would say this approach is not ready for prime time and will need further research."
Dr. Brand added: "I think their approach is the right approach. You have to do something before doing an EUS to make that more cost effective. Although the study is very thought provoking, it is by no means a definitive study."
Dr. Zubarik, Dr. Ma, and Dr. Brand have disclosed no relevant financial relationships.
Gastrointest Endosc. 2011;74:87-95. Abstract
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