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Magnetically assisted capsule endoscopy as a mass screening tool: is it ready for prime time?Referring to Li Z et al. p. 914–919
In their study entitled “Screening for upper gastrointestinal cancers with magnetically controlled capsule gastroscopy: a feasibility study,” Li et al. report on the use of magnetically controlled capsule gastroscopy (MCCG) to screen 6627 asymptomatic individuals in Shandong, a province in China where the incidence of upper gastrointestinal (UGI) cancer is considered to be high . This was a feasibility study that reported success in detecting UGI cancers in 0.48 % of participants, among whom four had early gastric cancer and one had early esophageal cancer. The five early cancers were amenable to endoscopic resection. Ulcers were also detected in 3.76 % of these asymptomatic individuals. There were no complications associated with the examination. It is worth noting that the study population may not be extrapolated to the general population as it was a relatively young group, with a relatively low prevalence of smokers and drinkers.
This presentation of the Shandong Consortium’s experience with a non-invasive screening tool represents a potential game changer, with several valuable propositions. Firstly, designed with an accuracy comparable to that of gastroscopy , MCCG will appeal to individuals who are reluctant to come forward for screening because of their fear of the discomfort associated with endoscopy. Secondly, it empowers primary care providers, who can now make a diagnosis without necessarily referring their patients to the tertiary centers. The shift of care from tertiary centers to primary care facilities will surely be strategically beneficial to the healthcare ecosystem in terms of resource allocation. Thirdly, MCCG is also a suitable case to test the internet-hospital concept. By carefully mapping out the workflow among the three partners (i. e. the patient, the primary care provider, and the specialist) and by utilizing the power of technology (in this case, MCCG and the cloud system), the current healthcare system could potentially move towards a more patient-centric one.
“...MCCG will appeal to individuals who are reluctant to come forward for screening because of their fear of the discomfort associated with endoscopy.”
Since Swain et al.  tested a magnetic maneuverable wireless capsule in a volunteer in 2010, much has been achieved in the development and refinement of magnetically guided capsule endoscope. In a multicenter blinded tandem study in 350 patients with upper abdominal complaints, a group from China demonstrated that MCCG was able to detect gastric lesions with a sensitivity of 90.4 %, a specificity of 94.7 %, a positive predictive value of 87.9 %, a negative predictive value of 95.9 %, and an accuracy of 93.4 % . What is also impressive is the finding that almost all patients preferred MCCG compared with gastroscopy. The latter finding opened the door for MCCG to be explored as an alternative to screening by gastroscopy. Several groups have since studied the possible uses of MCCG to screen for various UGI lesions. In addition to the feasibility study of MCCG in screening for gastric lesions by Li et al. in this issue of Endoscopy, another group have explored the role of MCCG in screening for Barrett’s esophagus and esophageal varices . They found magnetically assisted capsule endoscopy (MACE) to be very sensitive (93.8 %) and specific (100 %) for diagnosing Barrett’s esophagus. In another study in patients with suspected UGI bleeding, MACE was able to correctly identify patients who were safe for discharge .
Despite these promising results, several key issues will need to be resolved before MCCG can be recommended as the first-line screening tool for UGI lesions. Presumably because of its lower volume of use compared with that of gastroscopy, MCCG is currently more costly than gastroscopy. Its performance is also relatively labor-intensive and time-consuming. In the study by Li et al., the entire operation involved 38 capsule guiding machines, 53 examiners/operators, 18 experienced endoscopists, and an unknown number of coordinators to screen 6627 individuals over a period of 9 months. Although not mentioned by the authors, an earlier study by another Chinese group stated that the MCCG examination time was about 30 minutes , which is longer than that of an average gastroscopy. In addition, as capsule endoscopy does not allow tissue biopsy, a gastroscopy subsequently has to be performed to confirm any significant lesions. This second procedure may pose issues in terms of increased costs and reduced compliance.
Apart from the limitations as described above, other barriers to wider adoption of this technology may include its lack of biopsy or therapeutic capability. Several groups have made initial efforts to develop a MACE system that is capable of performing tissue biopsies  or therapy. Our group has been involved in developing a therapeutic capsule that promotes weight loss . Once the magnetic capsule reaches the subject’s stomach, an external hand-held magnet, much smaller than the machine described by Li et al., triggers a chemical reaction that releases carbon dioxide to inflate the balloon. The same external magnet can deflate the balloon to allow the capsule to be excreted. A first in-human study has demonstrated the feasibility of inflating the balloon using an external magnet .
Preliminary data presented in the article by Li et al. suggest that MCCG is a promising enabling technology. Further studies are needed to confirm the screening value of MCCG in a high-risk population and determine its cost-effectiveness when compared with standard gastroscopy in this setting. If MCCG proves to be both valuable and cost-effective as a screening tool, it will likely be widely adopted. It is hoped that wider acceptance of MACE will lead to significantly lower costs for this non-invasive technology.
26 August 2021 (online)
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