Presently, there is no agreed upon screening test to aid in the identification or earlier diagnosis of pancreatic cancer (ductal adenocarcinoma of the pancreas) for the general population. There is the beginning of the establishment of protocols involving periodic testing procedures at certain academic institutions to follow persons at high risk for pancreatic cancer, but these measures have not been well studied yet.
The best known of the blood markers for pancreatic cancer is CA19-9, a “carbohydrate associated antigen” also known as a sialylated Lewis (a) antigen. This marker is somewhat uneven in the diagnosis of pancreatic cancer, but can be quite elevated in those with pancreatic cancer. Approximately 10% of Caucasians lack the Lewis antigen, so in them the CA19-9 is not expressed. Currently, some oncologists appear to feel that the best use of the CA19-9 marker is as a guide to follow the disease and treatment process in a given individual patient.
There are mutations in specific DNA genes that are found commonly in pancreatic cancer. Some of these well-known genes are k-ras, p53 and p16. Because of the development of genetic micro-array tools (that allow for a huge number of tests all at once), in the past decade there has been a remarkable increase in research looking for genetic fingerprints to aid in the screening for and earlier diagnosis of pancreatic cancer. And although there has been a big increase in knowledge about DNA mutations and specific genes involved in pancreatic cancer, thus far this has not translated (yet) into screening tests or a diagnostic marker for pancreatic cancer. However, it remains an area of great interest.
A related area is represented by the many proteins that emanate from genetic instruction. The whole of this array of proteins is called the proteome. There has been considerable research in this area to try to detect reliable protein patterns in pancreatic cancer that will allow for screening or earlier diagnosis. Thus far, much has been learned but no universally recognized markers have been established through the study of protein patterns.
Many other agents have been studied as screening and diagnostic markers without much success. Some of these include cell surface associated mucins (MUC), carcinoembryonic antigen (CEA), and heat shock proteins (HSP).
Apart from the genome and proteome, another area of great recent research interest in screening and diagnostic markers for pancreatic cancer has been in that of MicroRNAs. First characterized in the 1990s, MiRNAs are small (22 nucleotide) non-coding RNA molecules involved in genetic regulation. There have been many recent intriguing study results looking at patterns of various MiRNA types in pancreatic cancer.
Researchers have looked at many tissues and access points to study these potential markers including in stool, pancreatic juice, saliva and blood.
The amount of research into the area of finding a means of screening for or providing for the earlier diagnosis of pancreatic cancer has increased dramatically in the past decade. It is a promising arena, as finding pancreatic cancer earlier would likely enable many more patients to avail themselves of surgery, for example. Much more is known than in the past. And is seems likely that this big knowledge will eventually lead to practical results. But despite gains we are not there yet. Some of the more recent developments in this area have been discussed in detail in our Pancreatica Blog.