AGA Tech Summit

Noninvasive esophageal cancer screening approaches may reach more at-risk patients


 

FROM THE 2022 AGA TECH SUMMIT

A rise in esophageal adenocarcinoma (EAC) cases and deaths showcases a need for noninvasive screening methods that can be performed by nonendoscopists, such as nurses or technicians, according to a presentation at the 2022 AGA Tech Summit that reviewed the new approaches. AGA’s annual innovation summit is sponsored by the AGA Center for GI Innovation and Technology.

Mortality rates are high, because the cancer is usually found after obstructive symptoms. Screening for Barrett’s esophagus (BE) and associated dysplasia could lead to earlier diagnosis and better prognoses, but endoscopic screening is costly and invasive, and few at-risk patients take advantage of it.

Some new approaches have the potential to screen more patients and detect earlier stages of disease, according to Prasad Iyer, MD, director of the esophageal interest group in the division of gastroenterology and hepatology at the Mayo Clinic in Rochester, Minn.

The estimated rise in EAC ranges from 400% to 600% between 1975 and 2000. The 5-year survival of EAC hovers at around 20%. “Not only is the incidence increasing, but the mortality associated with the disease is also increasing at a similar pace,” said Dr. Iyer during his presentation.

The only known precursor to EAC is BE, which has made the condition a focal point in screening. “If we can screen those with risk factors, we can identify those with prevalent Barrett’s. We then can put those with known Barrett’s into surveillance to detect cancer or high-grade or low-grade dysplasia. And then we when we find dysplasia or early cancer, we can intervene hopefully endoscopically to prevent or treat this progression from Barrett’s to adenocarcinoma,” said Dr. Iyer.

Endoscopic treatment of dysplasia achieves similar long-term survival outcomes to esophagectomy,Dr. Iyer said. Clinical studies have shown that radiofrequency ablation of high-grade and low-grade dysplasia reduces progression to cancer.

Low screening rates miss at-risk patients

Unfortunately, only 10%-12% of esophageal cancers are detected during surveillance, partly because many with BE are unaware of the condition and therefore don’t enter surveillance. “Two-thirds of the patients with Barrett’s are not under surveillance, so it’s not surprising that most esophageal cancers, unfortunately, are still being diagnosed after the onset of obstructive symptoms,” said Dr. Iyer.

A key issue is that sedated endoscopy is the only available screening tool, and it is expensive and invasive. “Only 10% of those who should get evaluated for the presence of Barrett’s are currently getting evaluated,” said Dr. Iyer.

Those issues have led to a movement to develop noninvasive methods for screening that could be performed by nonendoscopists, such as nurses or technicians. Dr. Iyer noted the importance of sensitivity and specificity of any test, but access to the test and participation are often overlooked factors.

“We hope that, by developing a nonendoscopic, minimally invasive test, we can increase access by allowing nonphysicians to perform this test. By keeping the costs low, we make this strategy cost effective, and hopefully get buy in for reimbursement from payers,” said Dr. Iyer.

New screening methods on horizon

He reviewed several noninvasive screening methodologies in development.

Unsedated transnasal endoscopy has been used successfully to diagnose BE, but the technique has not gained much traction in the United States.

Some devices collect esophageal cells, and then test them for various biomarkers. These include EsophaCap, CytoSponge, and the ESOCHEK Balloon. The procedure requires the patient to swallow a device, which is attached to a string or cord. After a few minutes, the device expands into a sphere or balloon, and the operator pulls it out through the esophagus, collecting 3-4 million esophageal cells in the process.

Biomarker analysis of the cells can include the protein trefoil factor 3 and methylated DNA markers. Case-control studies have shown this approach can achieve sensitivities of 76%-94%, and specificities of 62%-92%. “At least in case-control studies, this technology has been shown in thousands of patients now to be well tolerated, very safe, with a low risk of detachment, and can be done by a nurse in an office setting in less than 10 minutes,” said Dr. Iyer.

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