大腸カプセル内視鏡

Recent Advances and Future Perspectives of Colon Capsule Endoscopy

要旨●大腸カプセル内視鏡は2009年より第二世代に移行し，本邦では2014年1月に保険収載された．この第二世代の大腸内視鏡カプセルは視野角172°のカメラをカプセル両端に有し，撮影枚数を自動に調節するAFRや病変サイズが計測可能なPSEが搭載されており，径6mm以上の大腸ポリープの感度は84〜91％，特異度64〜94％と報告されている．大腸カプセル内視鏡は，全大腸観察が困難な症例や，羞恥心などの心理的負担により大腸がん検診で便潜血陽性だが大腸内視鏡検査を躊躇している患者に対するオプションとしての可能性を秘めており，将来的には大腸がん検診の受診率向上への寄与が期待される．ただし，現時点では高コスト，前処置，適応，読影などの課題が山積しており，さらなる機器の改良や工夫が必要である．

　Conventional colonoscopy is the gold standard for diagnostic examination of the colon. However, the overall acceptance of this procedure is low due to patients' fear of complications or embarrassment. With the advanced technology used in PillCam^® CCE2（COLON 2 capsule endoscopy）, there have been marked improvements in diagnostic rates for CCE2 with regard to the detection of colonic polyps and colorectal cancer. CCE2 represents a minimally invasive, patient-friendly procedure that offers complete visualization of the colon and rectum. The acceptability of CCE2-based examination is extremely high. Patients with a previously failed colonoscopy could be offered CCE2 examination as an optional procedure. There is low-quality evidence that CCE2 has good sensitivity and specificity for detecting colorectal polyps. In fact, low-quality evidence does not show a difference in accuracy between CCE2 and computed tomography colonography. There is also low-quality evidence that CCE2 has a good safety profile with few associated adverse events. CCE2 is a safe and effective means of detecting colorectal cancer and polyps in screening-positive cohorts（those with a positive fecal immunological test）and has the potential to reduce the number of optical colonoscopies. In addition, examination is limited not only to the colon, but also enables the detection of clinically relevant manifestations in other parts of the GI tract. Therefore, entire GI tract evaluation using CCE2 may be possible in the near future.