Study supports genetic testing for pancreatic cancer

Volume 7, Issue 4, 2018

Summary

Researchers identify six genes that contain mutations that may be passed down in families.

Fergus J. Couch, Ph.D.

Fergus J. Couch, Ph.D.

Gloria M. Petersen, Ph.D.

Gloria M. Petersen, Ph.D.

Six genes contain mutations that may be passed down in families, substantially increasing the risk of pancreatic cancer, according to Mayo Clinic research published in JAMA.

However, because researchers found these genetic mutations in patients with no family history of pancreatic cancer, they are recommending genetic testing for all patients with pancreatic cancer as the new standard of care.

Currently, health care providers offer genetic testing only to patients with pancreatic cancer with a family history of the disease. That accounts for just 10 percent of all cases of pancreatic cancer.

Research suggests that these testing guidelines miss genetic predisposition to cancer in up to 90 percent of patients with pancreatic cancer who have no family history of the disease. This finding is significant in part because the data suggest that family members should have DNA testing to understand their risk of cancer.

"This study provides the most comprehensive data to date supporting genetic testing for all patients with pancreatic cancer," said Fergus J. Couch, Ph.D., a geneticist at Mayo Clinic in Rochester, Minnesota, and a senior author of the published study. "This is the first study to provide estimates on the magnitude of cancer risk associated with each gene. It indicates that family history alone cannot predict who has these mutations."

Multiple genes can each increase risk of pancreatic cancer, said Gloria M. Petersen, Ph.D., also a geneticist at Mayo Clinic in Rochester, Minnesota, and a senior author of the published study. "But if genetic testing is performed only on patients with a family history of pancreatic cancer, then a small number of patients will be helped," she said.

Researchers performed genetic testing on 3,030 patients with pancreatic cancer who were seen at Mayo Clinic between 2000 and 2016. The test results of 21 cancer genes were compared to similar results from more than 123,000 patients without pancreatic cancer.

The study found six genes clearly linked to an increased risk of pancreatic cancer: BRCA1, BRCA2, CDKN2A, TP53, MLH1 and ATM. These genetic mutations were identified in 5.5 percent of all patients with pancreatic cancer, including 5.2 percent of patients with cancer who don't have a family history of pancreatic cancer. Patients who have these genetic mutations are at a substantially higher risk of pancreatic cancer, but that does not definitively mean they will develop the disease.

"The conclusion of this study is that we now have better molecular insights into the underlying genetic causes of pancreatic cancer," said Raed Samara, Ph.D., a study author from QIAGEN Sciences Inc., which designed the DNA testing for this research. "The comprehensive data generated from this cohort required the specific and uniform sequencing, and deep analyses of a focused set of cancer predisposition genes. The risks of developing pancreatic cancer due to mutations in these genes can be more accurately estimated than ever before because of this seminal study."

The researchers cautioned that more clinical trials are needed to replicate these pancreatic cancer findings.

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