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Colonoscopy is the gold standard for evaluating pathologies of the large bowel, including screening for colorectal cancer.
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Conventional colonoscopy is, however, invasive and costly and it may be contraindicated in selected patients. It has associated procedural risks, including the need for conscious sedation.
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The concept of capsule colonoscopy appears to represent a safe and promising new technology for visualizing the colon.
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Benefits of colon capsule; without intubation, no insufflation, no pain, no sedation, direct visualization and no radiation.
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Colon capsule endoscopy appears to be a promising new modality for colonic evaluation.
Progress ReportThe colon—the latest terrain for capsule endoscopy
Introduction
Hirschowitz developed a fiberscope viewing bundle and used it to perform the first flexible gastroduodenoscopy almost five decades ago [1]. Around 10 years later, Overholt reported on 40 successful flexible sigmoidoscopies [2]. At about the same time, technology improved and soon the first colono-fibrescope became available [3]. Colonoscopy has since become the gold standard for colon diagnosis and therapy, with an overall risk of complications of diagnostic colonoscopy of 0.3%, rising to 2% when it includes a therapeutic procedure [4], [5], [6].
Most experts today consider conventional colonoscopy to be the best available method for both colorectal cancer (CRC) screening and imaging the colon for colonic disease [7]. Conventional colonoscopy is, however, invasive and costly and it may be contraindicated in selected patients. It has associated procedural risks, including the need for conscious sedation or, in some places in the world, deep sedation. Despite the ever-growing body of evidence supporting the benefits of CRC screening with conventional colonoscopy, most eligible average-risk persons do not undergo any form of screening whatsoever [8]. Numerous reasons have been postulated to explain this observation, including patient fears, presumed procedural discomfort and embarrassment [9], [21]. The reluctance to undergo what, in many cases, could be life-saving screening led to the need for a new technology that is accurate and safe while being more patient acceptable and less skill-dependent. This brought about the development of several new techniques for examining the colon as a possible alternative to traditional colonoscopy, but they are all invasive [10].
Computed tomographic (CT) colonography has recently emerged as an alternative for examining the large bowel. Specifically, it combines helical CT scanning of the cleansed and distended colorectum with complex image-rendering techniques that simulate the view obtained by conventional endoscopy [11], [12]. This technology is attractive because it is simple to perform (for patients), it is probably very safe (although reports of colon perforation, usually in elderly patients and those with underlying colon disease, have emerged [22], [23] and there is controversy about the risk of radiation exposure. Two large multi-centre studies have demonstrated that CT colonography was significantly less sensitive than colonoscopy [7], [13], whereas another demonstrated that CT colonography was more sensitive than colonoscopy for detecting lesions ≥10 mm [11], [12]. Detection of tumour-derived DNA alterations in stool is an intriguing new approach with high potential for the non-invasive detection of CRC, but that approach is not yet ready for clinical application [14].
The ideal screening method for CRC should be non-invasive, safe, not operator-dependent, well accepted by the target population, cost-effective and of high diagnostic accuracy. In the continuing search for such non-invasive methods, wireless capsule endoscopy emerged as an attractive approach to mass screening. Since the beginning of this millennium, the PillCam™ small bowel capsule endoscope (Given Imaging Ltd., Yoqneam, Israel) has become the gold standard for evaluating obscure gastrointestinal bleeding and other small bowel pathology [15], [16], [17]. It seemed reasonable to take this concept one step further and apply wireless capsule endoscopy to evaluate the large bowel as well, and this led to the development of the PillCam™ Colon capsule endoscope (Given Imaging Ltd., Yoqneam, Israel) for visualizing the colon.
The 11 mm × 32 mm PillCam™ Colon capsule has dual cameras, a wide visual optic field, an automatic light control, a frame rate of 4 frames per second and a total operating time of approximately 10 h (Fig. 1). Following the initial activation of the capsule and several minutes of image transmission, the capsule enters a 2-h delay mode after which it is programmed to reactivate and transmit images. Similar to the PillCam™ small bowel and oesophageal capsules, the colon system includes a sensor array and data recorder worn by the patient during the procedure. The capsule has tiny cameras at each end which capture four images per second for up to 10 h. Each camera contains automatic lighting control and captures more than twice the coverage area and depth of field of the PillCam™ small bowel capsule that is used to diagnose diseases in the small intestine. The recorded data are downloaded into the Given Imaging RAPID® workstation for later review of the video (Fig. 2, Fig. 3).
The preparation of the colon needs to be more fastidious than that for standard colonoscopy: all residual material must be cleared since there is no way to suction it. The propelling of the capsule through the colon is completely different from that of the small bowel due the differences of the physiology of the colon which has only six longitudinal contractions per day [20]. Thus, the answers to the questions of whether the colon capsule could pass through the entire colon while transmitting images and identifying colonic pathologies could not be extrapolated from the experience with the small bowel capsule and needed further investigation.
Currently there are five ongoing trials which are designed to evaluate the colon capsule in comparison to standard colonoscopy. Two of them have already been published, one carried out in three Israeli medical centres [18] and the other in a Belgian trial [19]. A USA trial that involves a three-arm blinded investigation for comparing capsule colonoscopy, standard colonoscopy and virtual colonoscopy (presented at the meeting of the American College of Gastroenterology Las Vegas, NE, USA, October 2006), a pan-European trial (described in part at the Digestive Disease Week meeting, Washington DC, USA, May 2007) and two multi-centre trials in the USA and Europe are still ongoing.
A total of 91 individuals were enrolled in three Israeli medical centres (Rambam, Hillel-Yaffe and Bikur Holim) [18]. The results were evaluable in 84 cases (seven patients were excluded because of inability to swallow the capsule [n = 1], failure to adhere to the preparation procedure [n = 2], failure of the capsule to progress past the stomach for the entire examination time [n = 1] and technical capsule failures [n = 3]). All of these study patients underwent capsule colonoscopy with the PillCam™ Colon and were scheduled for traditional colonoscopies later in the day. Polyps of any size were found in 45 patients by both screening methods. PillCam™ Colon identified 76% (n = 34) compared to 80% (n = 36) by colonoscopy. Twenty of the 84 patients (24%) had significant findings, defined as at least one polyp measuring 6 mm or ≥3 polyps of any size. Of these, PillCam™ Colon identified 14 (70%) and colonoscopy identified 16 (80%). There were no adverse events with the exception of one patient who had severe abdominal pain immediately following traditional colonoscopy. The colonic preparation was well tolerated in all cases.
The Belgian study [19] was a single-centre (Brussels) comparative study of patients who presented for colorectal screening when polyps or CRC was suspected. Significant findings were defined either as polyps >6 mm, or ≥3 polyps of any size. Forty-one patients with a mean age of 56 years were enrolled into the study. Four patients were excluded due to technical problems (e.g., the capsule covered less than 20% of the colon length or failed to progress beyond the caecum) and one could not swallow the capsule, leaving 36 patients for analysis. The capsule had not been expelled after 10 h and was retrieved endoscopically in six of them. The PillCam™ Colon identified 19 of the 25 patients (76%) with positive findings and 10 of the 13 (77%) with significant lesions as detected by colonoscopy. The PillCam™ Colon detected seven lesions not seen at colonoscopy, two of which were detected by both examinations. The overall sensitivity of the PillCam™ Colon in detecting significant lesions was 77%, with a specificity of 70%, a positive predictive value of 59% and a negative predictive value of 84%. There were no adverse events. The authors concluded that further improvements in the procedure will probably increase the rate of capsule examination completion as well as polyp detection rates.
Both published studies [18], [19] proposed that the PillCam™ Colon showed promising accuracy compared with colonoscopy (Table 1).
The USA trial (presented at the meeting of the American College of Gastroenterology Las Vegas, NE, USA, October 2006) included 51 subjects and compared capsule colonoscopy, standard colonoscopy and virtual colonoscopy. The sensitivity was 79% for the capsule, 89% for conventional colonoscopy and 32% for CT colonography. The specificity of the capsule was, however, only 53%, compared to the 97% and 100% for CT colonography and standard colonoscopy, respectively (Table 2).
Additional multi-centre trials are underway in the USA and Europe. A seven-centre USA trial targeted 340 subjects and is designed to evaluate and compare the accuracy and safety of PillCam™ Colon capsule endoscopy for patients with significant findings on standard colonoscopy. It will also assess the diagnostic yield of the colon capsule in detecting pathologies compared to standard colonoscopy. An eight-centre European study targeted 329 patients for a double blind study comparing standard colonoscopy to PillCam™ Colon capsule endoscopy, and initial data are already available on 84 of them (presented at the Digestive Disease Week Meeting, Washington DC, USA, May 2007). The capsule had a sensitivity of 79% and a specificity of 78% for the detection of polyps (Table 3). The authors concluded that the colon capsule might challenge colonoscopy for CRC screening.
There are a number of problems associated with this new technology that will need to be dealt with before the capsule could be recommended for regular clinical application. One disadvantage of the colon capsule that emerged from these first investigations concerns the preparation of the bowel: the colon must be clear of all residual material since it is not possible to suction off the material as is done in regular colonoscopy. The thorough cleaning also contributes to facilitating the progression of the capsule. Therefore, in addition to the restricted diet and preparation with 4 l of polyethylene glycol, the trial patients also received a prokinetic drug (Tegasord 6 mg or Domperidone 10 mg) and a booster of at least one dose of sodium phosphate (30–45 ml), with a second dose given in cases in which the colon capsule was not excreted 10 h after its ingestion. The stringent preparation was the main reason for subject unwillingness to undergo the procedure. Another limitation is that 10 h after capsule ingestion, only 78–90% of the video capacity was captured by the capsule due to battery limitations. Finally, the capsule needs more refinement for precisely locating the lesions and determining the size of the polyps.
The concept of capsule colonoscopy is sound and the procedure appears to represent a safe and promising new technology for visualizing the colon. It can serve as a complementary technique to traditional colonoscopy when colonoscopy is incomplete or when colonoscopy is contraindicated, and for patients who are unwilling to undergo it. We believe that there is a solid place for capsule colonoscopy in the armamentarium of the clinical gastroenterologist. Currently there are five ongoing trials which are designed to evaluate the colon capsule in comparison to standard colonoscopy. The colon capsule is well accepted by patients. The quality of the colonic images and the diagnostic yield of colon capsule were good. Overall detection rate of polyps and other pathologies is good. The colon capsule showed promising accuracy compared with colonoscopy. Large-scale multi-center comparative studies are needed to confirm these data.
Section snippets
Conflict of interest statement
None declared.
Acknowledgement
Esther Eshkol is thanked for editorial assistance.
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Cost-effectiveness of colorectal cancer screening - An overview
2010, Best Practice and Research: Clinical GastroenterologyCitation Excerpt :A more careful examination of radiation risks and extra-colonic findings is needed [67]. Finally, capsule endoscopy is the least developed of the emerging CRC screening tests [69,70]. To date, only one study has evaluated the cost-effectiveness of capsule endoscopy [71].
The new PillCam Colon capsule: difficult colonoscopy? No longer a problem?
2008, Gastrointestinal EndoscopyCitation Excerpt :PCCE provides a safe and well-accepted modality for colon evaluation, and it may represent a valid alternative in cases of difficult or incomplete colonoscopies. The sensitivity, specificity, and positive and negative predictive values for PCCE have been reported to be 76%, 64% to 100%, 83% to 100%, and 54% to 78%, respectively,1-4 suggesting a promising beginning. We report a case in which the standard colonoscopy was incomplete because of the presence of a sigmoid stricture.
Colon capsule endoscopy
2008, Gastroenterologia y Hepatologia ContinuadaReducing the Incidence and Mortality of Colon Cancer: Mass Screening and Colonoscopic Polypectomy
2008, Gastroenterology Clinics of North AmericaCitation Excerpt :Ideally, if these deficiencies are corrected, videocapsule endoscopy could provide an initial screening examination of the colon. A lesion detected by this examination would prompt colonoscopy to confirm the diagnosis, to determine the histology of the lesion by colonoscopic biopsy, and potentially to remove the lesion by colonoscopic polypectomy [117]. In a pilot study, in which 41 patients underwent both capsule endoscopy and colonoscopy, capsule endoscopy had a sensitivity of 77% and specificity of 70%, using colonoscopy as the gold standard [118].
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Prof. Fireman is a member of the medical advisory board of Given Imagining Ltd.