隆起型早期大腸癌の内視鏡診断—pit pattern診断の立場から

Pit Pattern Diagnoses for Protruding Early Colorectal Cancer

要旨●今回，当施設で経験した1,284例の隆起型早期大腸癌のpit patternと壁深達度について検討した．隆起型T1b癌におけるV_N型pit patternの特異度は99.5%であったが，T1b癌の中でV_N型，V_I型高度不整pit patternを呈した病変は58.2%にすぎなかった．V_I型高度不整pit patternを呈した病変でみると，32.4%がTisもしくはT1aであった．隆起型早期大腸癌では，粘膜内病変を保ったまま，粘膜下層深部へ浸潤する症例や，V_I型高度不整であっても深部浸潤していない症例をしばしば経験する．このように，隆起型早期大腸癌ではpit pattern診断の限界があることに留意し，他の肉眼形態と比べてより慎重に治療方針を決定する必要がある．

　In this study, we retrospectively analyzed 1,284 patients with protruding early colorectal cancer and their pit pattern findings. When we assumed the type V_N pit pattern as an indication of T1b cancer, the specificity was 99.5%. Conversely, the proportion of T1b cancers that were revealed to be type V_N or having a V_I high-grade pit pattern was only 58%. Thirty-two percent of the lesions with a V_I high-grade pit pattern were Tis or T1a cancer. Protruding colorectal cancer often invades the deep submucosal layer without exposing the submucosal cancer tissue. Therefore, it is necessary to carefully determine the treatment procedure for protruding early colorectal cancer compared to other macroscopic types of cancer.