Feb. 14, 2020
Optical colonoscopy facilitates the detection and removal of premalignant polyps and is the gold standard as a screening and surveillance tool for colorectal cancer (CRC). Despite the demonstrated track record of the procedure, a number of factors limit patient acceptance of this test.
Concerns about adverse events, the required colon-cleansing prep, the need for sedation and pain control, loss of work time, and costs associated with optical colonoscopy are among the issues that negatively affect patient tolerance.
In addition, inadequate cleansing before the test can reduce cancer detection rates and lead to the need for repeat procedures.
Mayo Clinic researchers, in collaboration with others, are working to assess and advance capsule-based technology for CRC screening. According to Elizabeth Rajan, M.D., a gastroenterologist and researcher from Mayo Clinic's campus in Rochester, Minnesota, one of the newest capsule imaging systems currently being studied is a prepless, disposable and ingestible X-ray imaging capsule.
Prepless, disposable and ingestible X-ray imaging capsule
One of the newest capsule imaging systems currently being studied is a prepless, disposable and ingestible X-ray imaging capsule. Photo reprinted with permission from Check-Cap Ltd.
The capsule system that Dr. Rajan and others are studying uses an ingestible capsule that emits and detects ultra-low-dose radiation and requires no cathartic cleansing or sedation. The capsule generates a 3D reconstruction of the colonic lumen for detection of polyps and cancer. The system also includes a tracking device that utilizes processing units combined with radiofrequency (RF) communication to allow data transmission to an externally worn recorder attached to the lower back. In addition, it utilizes electromagnetic tracking technology to enable the device to track the capsule's 3D position and orientation within the body.
After ingesting the capsule, patients drink a small amount of contrast agent and fiber supplements with each meal during capsule passage. Patients can go about their daily activities and return to work. While the capsule travels naturally through the gastrointestinal tract, it scans the colon in a 360-degree arc and sends information to a recorder. Once the capsule is excreted, data from the recorder is downloaded to a workstation and analyzed to create a map of the colon.
Results from clinical trials
Safety and feasibility
Researchers from Germany and Israel first assessed the safety of this new generation of the prepless capsule system in two separate studies. The results of those studies were published in Abdominal Radiology in 2017 and demonstrated the safety and feasibility of this device in 141 study participants.
The same prepless capsule device underwent additional testing in a prospective multicenter trial conducted in Israel. During that trial, study participants underwent the capsule procedure and concomitant fecal immunochemical test (FIT) followed by colonoscopy, with removal of all visualized polyps.
Results from this trial were published in Gut in 2019 and included these relevant findings:
- An analysis of 45 procedures performed demonstrated the sensitivity of both approaches for polyp detection: 44% using the capsule and 37% using FIT.
- Capsule sensitivity increased to 78% to 100% when more than 50% to 70% of the colon surface area was imaged, respectively, with a linear correlation between imaged area and sensitivity. Specificity varied from 86% to 90%. Optimized scanning algorithms will be applied to future studies.
- The average transit time was 52 hours with no device-related serious adverse events.
Ongoing and future trials
Dr. Rajan and colleagues are collaborating in the first U.S. prospective single-arm pilot study evaluating the safety and compliance of this prepless capsule in asymptomatic participants considered to be of average risk of polyps and colon cancer. Preliminary results are promising, and Dr. Rajan and co-investigators expect to publish results from that trial in early 2020. The next step will be a multicenter pivotal study.
"Each phase of this research helps us progress toward the goal of offering patients the option of a prepless, X-ray-based imaging capsule as a screening tool for CRC," says Dr. Rajan. Establishing the safety and efficacy of this screening test may encourage more nonadhering patients to comply with recommended screening, which would, in turn, help reduce the overall incidence of CRC.
For more information
Kimchy Y, et al. Radiographic capsule-based system for non-cathartic colorectal cancer screening. Abdominal Radiology. 2017;42:1291.
Gluck N, et al. Novel prep-less X-ray imaging capsule for colon cancer screening: A feasibility study. Gut. 2019;68:774.