Noninvasive Esophageal Cancer Screening May Reach More At-Risk Patients

Jim Kling, MDedge News

May 10, 2022

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 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 Iyer.

Endoscopic treatment of dysplasia achieves similar long-term survival outcomes to esophagectomy,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 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 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. 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 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 Iyer.

Earlier Detection of Barrett's

He summarized a randomized, controlled trial, published in 2020 in The Lancet, which tested this approach in patients who had taken proton pump inhibitors for at least 6 months. It compared 6,983 patients screened using the CytoSponge/TFF3 with 6,531 usual-care patients who only underwent screening if their physicians recommended it.

In the screening group, 140 patients were diagnosed with Barrett's Esophagus, compared with 13 in the usual-care group. There were nine cases of dysplastic Barrett's and five cases of stage I EAC in the screening group, versus no dysplastic Barrett's and three advanced stage EAC cases in the usual care group. "You can see how we can shift the spectrum of patients with Barrett's if we go for early detection," said Iyer.

Another noninvasive strategy relies on sensors to detect exhaled volatile organic compounds. After a patient breathes into the detector for about 5 minutes, an artificial neural network distinguishes molecular patterns indicative of the presence or absence of BE. The technique had just moderate sensitivity and specificity, "But this is very noninvasive and even less invasive than [sponge or balloon]-based technology," said Iyer.

Other efforts are underway to identify plasma biomarkers for screening. Iyer and colleagues have developed methylated DNA markers for EAC and squamous cell cancer. So far, they have achieved sensitivity and specificity just above 80%. "Not where we would want it to be, but certainly not terrible," said Iyer, adding that they are performing a larger prospective study.

He described a potential screening program that could draw from electronic medical records or even apps to identify patients with risk above a defined threshold who would then be tested with minimally invasive techniques. Those with positive results would go on to confirmatory endoscopy. His group found that such a strategy would be cost effective even if reflux was not used as a qualifying criterion for screening.

Answering audience questions after the talk, Iyer was asked if noninvasive methods would directly compete with endoscopy, or if some patients would be better candidates for one or the other.

"That's something we need to think through. It's going to be very difficult for us to say every patient at risk should get an endoscopy. I just don't think that strategy is probably practical or cost effective. On the other hand, I think an all-of-the-above strategy is probably just fine. It's like elections. You have to be very local, your message has to be cost effective, available, and have adequate patient as well as provider buy-in," he said.

Iyer has received research funding from Exact Sciences, Pentax Medical, and Cernostics. He has consulted for Exact Sciences, Pentax Medical, Medtronic, Ambu, Cernostics, CDx Diagnostics, and Symple Surgical. The 2022 AGA Tech Summit was supported by independent grants from Castle Biosciences, Medtronic, Boston Scientific, Exact Sciences, Olympus, 3-D Matrix, Apollo Endosurgery, Motus GI Holdings, STERIS Endoscopy, Cook Medical, FUJIFILM Healthcare Americas, and Virgo.

This article originally appeared in GI and Hepatology News.


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