食道胃接合部腺癌の病理学的特徴―早期癌を胃上部と比較して

Histopathological Characteristics of Early Cancer in the Esophagogastric Junction, Compared with Gastric Early Cancer in the Upper Portion

要旨　「食道癌取扱い規約」が改訂され，食道胃接合部癌の定義が“病理組織型にかかわらず，食道胃接合部の上下2cm以内に癌腫の中心があるもの”とされた．その定義に従い，食道胃接合部腺癌の臨床病理学的特徴を早期癌を用いて検討するとともに，胃上部早期癌と比較検討をした．胃上部癌との比較では，食道胃接合部腺癌は平均年齢がやや高く，男性にやや多い．部位は，いずれも小彎側が多いが，胃上部癌は後壁にも多く認められた．肉眼型は，いずれも0IIc型が多いが，食道胃接合部腺癌は隆起型の頻度も高い．平均腫瘍径に違いは少ないが，食道胃接合部腺癌では長軸方向の長さが短いものが多く認められた．深達度は，食道胃接合部腺癌ではM癌が少なく，SM癌が多い．組織型は，食道胃接合部腺癌では高分化型管状腺癌が多く，また，低分化腺癌や印環細胞癌が認められない．また，食道胃接合部腺癌の粘液形質は胃型優位の胃腸混合型が多く認められた．食道胃接合部腺癌を領域別に比較検討すると，Gは肉眼型，深達度，組織型，粘液形質でほかの領域と違いがみられた．その結果，食道胃接合部癌の定義は，食道胃接合部からの長さを1cmに短く定義するとともに病変が食道胃接合部に及んでいることを要件に入れることが必要と考えられた．その定義に含まれるEG，E＝G，GEの癌はいずれも円柱上皮化生粘膜から発生するが，癌周囲の胃粘膜に違いが認められ，発生する場の違いによるものと捉えられた．

　According to the revision of the guidelines for the clinical and pathological studies on carcinoma of the esophagus, the esophagogastric junctional carcinoma （EGJC）is defined as existing when there is a center of a carcinoma less than 2 cm above or below the esophagogastric junctional line （EGJL）. Under this definition, the pathological characteristics of EGJC are studied in thirty-one cases of early cancers as compared with fifty-five cases of early gastric carcinoma located in the upper portion of the body （UGC）.

　Compared with the UGC, the average age of the EJGC patients is higher and there is a slightly higher proportion of males among the total number of cases. EJGC is mostly located in the lesser curvature, but UGCs are located in the lesser curvature and in the posterior wall. The macroscopic type of EGJC is not only superficial depressed type but also protruded type. The greatest dimension of EGJC is perpendicular to the major axis. SM cancers are more numerous M cancers. The histologic type is mostly well differentiated tubular adenocarcinoma, and there are not signet-ring cell carcinomas or poorly differentiated adenocarcinoma. Concerning the mucin phenotype of carcinoma, the gastric predominant type is most numerous. So clinicopathologically EGJC is different from UGC clinicopathologically.

　When EGJC cases are studied according to the sub-location, such as E, GE, E＝G, EG, G, which defined by the guidelines, in five locations, G is different from other areas in macroscopic type, invasion depth, histologic type and mucin phenotype. Considering these results, the definition of EGJC should be changed to include carcinomas whose center is less than 1cm above or below the EGJL, and in contact with or spreading across the EGJL.

　So carcinomas of EG,E＝G and GE will be the true EGJCs. Examining the surrounding mucosa,EG and E＝G are shift to the fundic gland mucosa, and GE shifts to the gastric mucosa with intestinal metaplasia. Thus,E＝G may have the same break point as EG.