Having found a way to address the disease’s genetic diversity, Pittsburgh-based researchers published a study Tuesday offering hope of a simple blood test for early detection of lethal esophageal cancer.
The study, published online by the journal Cancer, was conducted by researchers at Allegheny Health Network, the University of Pittsburgh, Roswell Park Cancer Institute in Buffalo, N.Y., and Academic Medical Center in Amsterdam.
The researchers identified four proteins associated with the onset of esophageal cancer, described as a rapidly increasing and particularly deadly disease. Identification of the biomarker panel is a precursor to developing a blood test for early detection and better treatment.
“We haven’t reached that goal yet, but that’s where we’re headed,” said Blair Jobe, director of Allegheny Health Network’s Esophageal and Thoracic Institute and the study’s lead author.
Research into blood-based biomarkers for cancer is “the search for the Holy Grail,” and the Pittsburgh study is a “landmark,” said Charis Eng, founding director of the Genomic Medicine Institute at Cleveland Clinic’s Lerner Research Institute.
“If this pans out in the end, it’s amazing,” said Dr. Eng, who was not involved in the study. She called for additional research to test the findings.
Steven DeMeester, professor of surgery at the University of Southern California's Keck School of Medicine and a member of the Society of Thoracic Surgeons, said the study is “super well done.”
But Dr. DeMeester, who wasn’t involved in the study, said it’s too early to say whether it will be a game-changer. He noted that it’s not yet known for sure how early or how reliably a blood test might detect the cancer.
Doctors long have sought an indicator for esophageal cancer, which has a five-year survival rate of less than 15 percent. Many efforts focused on the search for what Ali Zaidi, research director at the Esophageal and Thoracic Institute, called a “magic bullet” — a single biomarker that signals the disease, much like the prostate-specific antigen — or PSA — test has been used to indicate prostate cancer.
However, Dr. Zaidi said esophageal cancer varies so much from patient to patient that “the single marker doesn’t give you the broad spectrum of genetic coverage, the diversity of genetic content, across the disease.” A single marker would fail to catch many cases, he said, whereas the new, four-protein panel so far has shown an accuracy rate of 87 percent.
Among cancer researchers, the focus on biomarker panels has increased over the past couple of decades, said William Bigbee, a professor in the Pathology Department at Pitt’s School of Medicine who was part of the inter-disciplinary research team. The work has been aided, the biochemist said, by technology allowing “robust, deep genetic sequencing of individual tumors.”
Early detection for esophageal cancer is sorely needed.
According to National Cancer Institute estimates, 18,170 cases of esophageal cancer will be diagnosed year, and 15,450 people who have the disease will die.
The Pittsburgh-based study says the incidence of esophageal cancer is up 600 percent since the 1970s, outpacing increases in all other types of cancer. The obesity epidemic may be partly to blame, Dr. Zaidi said.
An endoscopy is the only reliable method of detection now.
However, by the time patients have the procedure because they’re experiencing difficulty swallowing, the disease often is well advanced. Esophageal cancer is detected early only in patients who have an endoscopy for another reason, such as symptoms of acid reflux disease.
Doctors have identified a link between Barrett’s esophagus — a tissue injury related to acid reflux — and esophageal cancer. Patients with the former face a lifetime of endoscopic monitoring so that doctors can move quickly if cancer develops.
“Every year, they have an endoscope stuck down their throat. How uncomfortable,” Dr. Eng said.
Yet the link is not absolute. Some people with Barrett’s esophagus never develop cancer, and nearly 60 percent people of people who develop the cancer have no symptoms of acid reflux,
An affordable blood test would allow periodic screening of those at risk for esophageal cancer, such as people who are obese or smoke or have been diagnosed with Barrett’s esophagus. Dr. Zaidi said the biomarker panel could lead not only to earlier diagnosis of esophageal cancer but to better monitoring of treatment once a diagnosis is made.
“We’re going to use this panel along with our personalized medical approach to help tailor therapy,” he said.
First Published August 5, 2014 12:00 AM