Nearly 20 million people in the U.S. suffer from gastroesophageal reflux disease, or GERD, and doctors have known for some time that it is a risk factor for esophageal cancer.
Yet only a small fraction of people with GERD develop esophageal cancer, and "the question is, why?" says Winson Y. Cheung, MD, a clinical research fellow working with the University of Toronto and the Harvard School of Public Health.
The new study is the first to identify specific genetic markers that are linked with increased cancer risk in people with GERD, he tells WebMD.
The research is being presented this week at the 2009 Gastrointestinal Cancers Symposium in San Francisco. The meeting is cosponsored by the American Society of Clinical Oncology (ASCO) and three other major cancer organizations.
If detected early, the cancer is more curable, but because screening is expensive and invasive (involving the insertion of an endoscope into the esophagus), it is not recommended for all patients with GERD.
Jennifer C. Obel, MD, says that the findings are a step toward identifying which patients are at highest risk of esophageal cancer and would benefit from more aggressive screening. Obel, a gastrointestinal cancers specialist at NorthShore University HealthSystem in Illinois, moderated a discussion of the findings.
Gene Variant Linked to Increased Esophageal Cancer Risk
For the study, Cheung and colleagues collected DNA samples from 309 people being treated for esophageal cancer and 275 healthy people without cancer.
People who had a mutated variant in the epidermal growth factor (EGF) gene and experienced symptoms of acid reflux more than once a month were nearly 10 times more likely to have esophageal cancer, compared with those who had the normal EGF variant and did not have GERD.
Esophageal cancer was increased more than 20-fold among people with the mutation who suffered GERD symptoms more than once a week or for more than 15 years.
Both Cheung and Obel stress that the findings need to be confirmed in larger numbers of people.
Gene Testing and Colon Cancer Treatment
Obel also announced new ASCO guidelines recommending that people with metastatic colorectal cancer be tested for KRAS gene mutations before undergoing treatment with the targeted drugs Erbitux and Vectibix.
Studies have demonstrated that only patients whose tumors have the normal form of the KRAS gene respond to treatment with the drugs. It is estimated that 40% of colon cancer patients have KRAS gene mutations and will not benefit, Obel says.
Weeding out people who will not benefit from Erbitux and Vectibix will result in significant cost savings to the health care system while sparing patients from side effects of ineffective therapy, Obel tells WebMD.
An economic analysis being presented at the meeting found that routine testing for KRAS gene mutations in patients with metastatic colorectal cancer could save the U.S. health system up to $604 million per year in the cost of Erbitux alone.
Genes Predict Response to Pancreatic Cancer Treatment
In a third study being presented at the symposium, researchers found that certain genetic variations may help predict whether people with pancreatic cancer will respond to treatment.
The researchers examined 15 variants in eight genes involved in repairing DNA damage caused by cancer treatment.
They found that 94% of pancreatic cancer patients with "good" gene variants responded to treatment with radiation and the chemotherapy drug Gemzar, compared with only 73% of people with "bad" gene variants.
People with good gene variants also lived longer. They survived a median of 25.5 months vs. 7.4 months for the "bad" genotype carriers, says Donghui Li, PhD, of the University of Texas M.D. Anderson Cancer Center in Houston.
Taken together, all "the studies bring us closer to the goal of distinguishing those patients most likely to benefit from screening and treatment from those who will not," Obel says.