After comparing the DNA of thousands of people with and without the disease, a new study has identified five genetic markers for pancreatic cancer that raise the risk for developing the deadly disease.
The international consortium of scientists reports the findings in the journal Nature Genetics. The discovery is the result of a third project in a series of genome-wide association studies that began in 2006 under the auspices of the National Cancer Institute (NCI) Cohort Consortium.
Pancreatic cancer is a cancer that occurs in the cells lining the ducts or the islet cells of the pancreas, a digestive organ that sits in the upper abdomen surrounded by the stomach, small intestine, liver, spleen and gall bladder.
The average age of diagnosis for pancreatic cancer is 70, and in the majority of cases the cancer is not diagnosed until is has spread, which unfortunately means the chances of survival are slim. The 5-year survival from the most common form – ductal adenocarcinoma – is 4%.
We currently know that smoking and having a close relative with pancreatic cancer can increase a person’s risk of developing the disease.
There is no effective screening test for pancreatic cancer, one of the leading causes of cancer deaths in the US. The PanScan project, which the NCI set up in 2006, is identifying genetic and environmental factors that contribute to the development of pancreatic cancer, together with ways to screen and improve the diagnosis of the disease so it can be detected earlier.
Cancer that is found earlier has a much better chance of successful treatment, as lead author Dr. Brian Wolpin of the Dana-Farber Cancer Institute in Boston, MA, explains:
“Currently, there is no population screening program for pancreatic cancer, which in 80% of cases is discovered when it’s too late to allow curative surgery – the cancer has already spread.”
A screening tool to identify people at increased risk for pancreatic cancer could help identify those who might be candidates to undergo MRI or ultrasound scanning to look for early, treatable pancreatic tumors, he notes.
The average lifetime risk of a person in the general population developing pancreatic cancer is 1.5%.
Currently, the only healthy people who are screened for pancreatic cancer are those thought to be at higher risk because they have several close relatives with the disease:
“But the field has been struggling to find factors that can identify people at highest risk in the general population, when a strong family history is not present,” explains Dr. Wolpin.
This new study, PanScan III, brings to nine the total number of significant genetic markers that the scientists have discovered for pancreatic cancer. The markers are single-nucleotide polymorphisms (SNPs or ‘snips’), where a single letter variation occurs in a sequence of DNA in the genome. For instance, in one person the sequence could be AAGCCTA, while in another person, in the same location on the genome, the sequence might be one letter different: AAGCTTA.
Such changes in DNA can alter the expression of a gene or change the content of its message – for instance to alter a key function of a cell, or make the wrong version of a protein.
Dr. Wolpin says as well as helping to develop a screening test for pancreatic cancer, another reason the discovery of the markers is important is that it will help researchers looking for molecular explanations of why some people are more susceptible to pancreatic cancer.
For the study, the scientists analyzed DNA from 7,683 patients with pancreatic cancer and 14,397 control patients without this cancer, all of European descent, from the US, Europe, Canada, and Australia.
They used sequencing technology to examine over 700,000 locations on the genome to find SNPs associated with pancreatic cancer susceptibility.
As well as finding five new markers, the new genome-wide association study (GWAS) also confirmed the presence of four risk-associated markers that had been discovered in a previous PanScan GWAS.
The scientists found the risks linked to each marker were mostly independent and additive, making them useful to include in a screening test of the general population.
The long-term aim is to develop a tool that can stratify risk of developing pancreatic cancer so doctors in primary care can identify patients who should have further screening with MRI and ultrasound scans.
PanScan III receives funding from several sources, including the National Cancer Institute of the National Institutes of Health, and the Lustgarten Foundation.
In March 2013, Medical News Today learned how scientists in Japan are working on a new diagnostic test for earlier detection of pancreatic cancer via metabolomic analysis, a method that uses gas chromatography mass spectrometry to measure levels of metabolites in the blood.