大腸カルチノイド腫瘍の内科治療適応に関する臨床病理学的検討

Clinicopathological Study of Colorectal Carcinoid Tumor, Focusing on the Indication for Endoscopic Mucosal Resection (EMR)

要旨　大腸カルチノイド48症例49病変を対象とし，転移に関する臨床病理学的因子，治療内容とフォローアップ成績などを検討した．腫瘍径別では，転移は10mm未満の病変に認めず10mm以上の病変で認め，その転移率はリンパ節40.0％，肝22.2％であった．深達度別では，転移はsm病変では認めずmp以深の病変で認めその転移率はリンパ節，肝とも66.7％であった．陥凹所見出現率は転移例で50％，非転移例で8.5％であった．脈管侵襲率は転移例で100％，非転移例で18.6％であった．Ki-67陽性率（陽性細胞10個以上/10HPF)は転移例で100％，非転移例では18.5％であった．今回の症例の平均経過観察期間は37.8±22.2か月（13～111か月)で，原病死した2例（いずれも転移例で手術例)を除けば，他は局所遺残・局所再発・転移などを1例も認めていない．また，文献検索による10mm以下の転移例は大半がsm病変で中心陥凹や脈管侵襲を高頻度（70％以上)に認めた．自験例と過去の論文報告の成績を勘案すると，直腸カルチノイドの治療方針は“腫瘍径10mm以下，深達度sm，脈管侵襲のない病変に対してはEMRなどの局所切除を行う（ただし，中心陥凹のある病変は適応を慎重にする)，それ以外の病変は原則的に根治的外科切除を行う”ことであると考えられた．

　We clinicopathologically investigated 48 cases (49 lesions) with colorectal carcinoid tumor focusing on risk factors of metastasis and evaluated the prognosis of the cases followed up after treatment.

　Concerning the relationship between tumor size and metastatic ratio, no metastasis was recognized in lesions less than 10 mm in diameter, but lymphnode and liver metastatic ratios were 40.0 ％ and 22.2 ％, respectively, in lesions over 10 mm in diameter.

　Concerning the relationship between the depth of tumor invasion and metastatic ratio, no metastasis was recognized in lesions whose invasion was limited within the submucosal layer, but lymphnode and liver metastatic ratio were 66.7 ％ in lesions invading beyond the submucosal layer.

　Depression on the surface of the lesion was detected in 50 ％ of the lesions with metastasis, but in only 8.5 ％ of the lesions without metastasis.

　Vessel invasion was recognized in 100 ％ of the lesions with metastasis, but in only 18.6 ％ of the lesions without metastasis.

　The Ki-67 positive ratio (over 10 positive tumor cells/10 HPF) was recognized in 100 ％ of the lesions with metastasis, but in only 18.5 ％ of the lesions without metastasis.

　32 cases were followed up for 37.8±22.2 months. No case showed local recurrence, but metastasis and death due to the original lesion followed in all except two cases who had metastasis but died due to the originals colorectal carcinoid.

　Hence, on principle, the treatment for colorectal carcinoid tumor should be, EMR or local resection applied to carcinoid tumors less than 10 mm in diameter with invasion confined to the submucosal layer and with no vessel invasion. However, radical resection is recommended for other carcinoid tumors.