早期胃癌内視鏡的切除の評価―病理の立場から

Radical Endoscopic Resection of Early Gastric Carcinoma: Major Problems Concerning Pathologic Evaluation

要旨　内視鏡的に切除される早期胃癌について病理学的には切除端と粘膜下浸潤の2つの問題がある．胃癌を便宜的に高分化型癌と低分化型癌に大別し，それぞれの問題について検討した．高分化型癌では，実体顕微鏡観察の裏付けと，十分に切り出された病理組織標本があれば，切除端に癌が認められなければ完全切除と診断する．低分化型癌の場合は，より厳しい判定基準が求められ，切除端と癌巣辺縁との間に0.5cm程の距離が必要と考える．粘膜下浸潤が認められた場合は，原則として外科的治療を追加すべきである．内視鏡的切除の対象となる病変は，1回の切除で完全採取が可能な比較的小さい病変に限るべきで，高分化型癌は2cm以下，低分化型癌は1cm未満の潰瘍や潰瘍搬痕を合併しない粘膜内癌である．正確な根治性の評価には，適切かつ十分な病理標本の作製が必要不可欠な条件である．

　There are two major problems in pathologically examining the material of endoscopically resected early gastric carcinoma; whether or not completely resected, and thorough examination for submucosal invasion. In the present study, gastric carcinoma is divided into two groups;well differentiated and poorly differentiated adenocarcinoma. The materials belonging to each group are discussed and evaluated separately.

　Conclusions

　1) To examine endoscopically resected material, it is indispensable to make adequate microscopic preparations from the material by means of careful stereoscopic examination.

　2) In case of well differentiated adenocarcinoma, absence of carcinoma at the margin is sufficient to judge the material completely resected.

　3) In case of poorly differentiated adenocarcinoma, the criterion for well differentiated adenocarcinoma does not hold. In our opinion, there should be at least O.5 cm between the margin and carcinoma to judge the material completely resected.

　4) In case of incomplete resection of well differentiated adenocarcinoma, endoscopic resection may well be repeated. However, in case of poorly differentiated adenocarcinoma, repeat endoscopic treatment is prohibited and surgical resection should be performed with lymph node dissection.

　5) When pathologic examination reveals submucosal invasion of carcinoma, surgical treatment is required as radical therapy of gastric carcinoma.

　6) Indication of endoscopic resection should be limited to small mucosal cancer without ulcer or ulcer scar, well differentiated adenocarcinoma less than 2 cm and poorly differentiated adenocarcinoma less than 1 cm in diameter.

　7) Endoscopic piecemeal resection of gastric cancer is contraindicated for radical treatment.

　In conclusion, making adequate microscopic preparations by means of careful stereoscopic examination is prerequisite for accurate evaluation of endoscopically resected early gastric carcinoma.