Barrett食道癌の深達度の評価と転移リスク

Depth of Tumor Invasion and Lymph Node Metastasis of Barrett's Adenocarcinoma in Japan

要旨　本邦ではBarrett食道癌の頻度が低いためBarrett食道癌の深達度の評価とリンパ節転移に関する研究は少ない．そこで，当院でリンパ節郭清を含む切除が施行されたBarrett食道癌64例の特徴を，深達度とリンパ節転移との関連を中心に検討した．Barrett食道癌のリンパ節転移率は45％で，深達度別にみると粘膜内癌で29％，粘膜下層浸潤癌で24％，固有筋層以深浸潤癌で71％であった．早期の分化型癌に限ると，リンパ節転移は腫瘍径20mm以上，粘膜下層深達度1,000μm以上，脈管侵襲陽性例に多く認められた．粘膜内癌で脈管侵襲あるいはリンパ節転移を認めたものが3例あり，いずれも腫瘍が粘膜筋板内に浸潤していた．このうち2例は分化型と未分化型の混在型で，もう1例は分化型であったが腫瘍径が80mmと大きかった．粘膜筋板が錯綜・断片化したものが多く，腫瘍の深達度診断はしばしば苦慮した．Barrett食道癌の深達度診断とリンパ節転移リスクの関連については今後，他施設共同研究を含めたさらなる議論が必要であろう．

　There have been few studies on the relationship between the depth of tumor invasion and lymph node metastasis, because of the low frequency of Barrett' adenocarcinoma in Japan. Therefore, we studied, clinico-pathologically, 64 surgically resected cases of Barrett's adenocarcinoma with lymph node dissection. The rate of lymph node metastasis was 45％ overall, 29％ of the intramucosal tumors（M）, 24％ of the submucosal invasive tumors（SM）and 71％ of the tumors invading deeper than the muscularis propria（MP）. Confined to the differentiated-type carcinoma in the early stage, tumors more than 20mm in size, more than SM 1,000μm in depth and with lymphatic invasion tended to have lymph node metastases. Among the intramucosal tumors, three cases were positive for lymphatic invasion and/or lymph node metastases, all of which were invading the muscularis mucosae. Two of these 3 cases were histologically composed of differentiated and undifferentiated type（mixed type）. Although another case histologically consisted of differentiated type, the size of the tumor was larger than 80mm. We felt difficulty in estimating exactly the depth of tumor invasion in the early stage, because the muscularis mucosae were often irregularly fragmented and regenerated. Further examination, including a multicenter study, would be needed to clarify the association between the tumor depth of Barrett adenocarcinoma and the risk of lymph node metastasis.