Wed 11 Jun 2014
Pancreatic cancer is often detected at a late stage, which results in poor prognosis.
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Researchers at The Sahlgrenska Academy at the University of Gothenburg in Sweden have now developed a method which examines fluid from small cysts which are present in most pancreatic cancers. If the success of the technique is confirmed in future studies it may become part of clinical practice.
The poor prognosis for pancreatic cancer, where only 5 percent of the patients survive five years after the diagnosis, is due to the fact that the tumours often develop unnoticed, and rarely cause symptoms until they have spread to other organs. Recent studies, however, have shown that fluid-filled compartments in the pancreas, called cysts, may be precursors of the cancer.
Cysts in the pancreas, are not uncommon being found in around 10% of people above the age of 70, and less commonly in younger people and are usually identified when computed tomography (CT) or magnetic resonance imaging (MRI) of the abdomen is performed.
However imaging alone cannot determine which cysts are at risk for developing into cancer. It is necessary to obtain a sample of fluid from within the cyst to test using cytology and measurement of the tumour marker Carcinoembryonic Antigen (CEA). Even if this is done there will be some false-negative results so the testing is not completely reliable.
Surgically removing the cyst without knowing if it is benign or malignant is also unsatisfactory as the pancreas is situated deep in the abdomen and the operation carries significant risks.
The Swedish researchers have developed a new type of test that can be done on the cyst fluid and in their study they were able to correctly identify 77 out of 79 cysts that they examined. The new test identifies special types of proteins called mucins that are secreted into the cyst fluid. The whole procedure is not straightforward however. Firstly the patient must undergo ultrasound-guided endoscopy with sampling of the cyst fluid. This means that a flexible tube with a camera and sampling needle at the end (an endoscope) is passed through the mouth down to the stomach or duodenum. Then using simultaneous ultrasound to visualise the cyst and the end of the needle, the needle is passed through the stomach or duodenal wall and into the cyst in the pancreas so that some fluid can be sucked out. This procedure requires a lot of technical skill. Once the fluid is obtained, some of it is used for cytological examination and another small portion for a very advanced analytical technique using a number of steps including gel electrophoresis and then liquid chromatography followed by mass spectrometry. This again requires a lot of technical skill and sophisticated analytical instruments. Because the test will be done infrequently it is unlikely that many of the steps can be automated.
This test is an example of a new field in biological and medical research called proteomics. So far proteomics has only been used in research laboratories but these researchers are confident that proteomics will find its way into clinical laboratories within the next five years. If this test can be made technically viable and affordable, then it could become a very useful way of identifying those patients requiring surgery and those who can be safely followed up without a major operation.
University of Gothenburg - News
JNCI - Proteomic Mucin Profiling for the Identification of Cystic Precursors of Pancreatic Cancer
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