ESD後のsurveillanceの有用性と問題点—LSBE由来の腺癌の異時多発癌リスク因子に着目して

The Usefulness and Issues of Surveillance after Endoscopic Submucosal Dissection：Focusing on Risk Factors for Metachronous Multiple Cancers in Patients with Long Segment Barrett's Esophagus-derived Adenocarcinoma

要旨●背景：本邦ではLSBE由来の腺癌は少なく，内視鏡的粘膜下層剝離術（ESD）後の適切なsurveillanceについては一定の見解を得ていない．適切なESD後治療方針決定のため，LSBE由来の腺癌の治療後異時再発のリスク因子を評価することを目的とした．方法：当院でESDを施行し，2年以上の経過観察が行われたLSBE由来の腺癌14例を対象とした．異時多発癌なし群と異時多発癌あり群に分け，その臨床病理学的特徴の違いについて，比較検討した．結果：対象症例中，4例（28.6%）で異時多発癌を認めた．病変の臨床病理学的特徴については両群間で差はなかった．一方，病変周囲の背景粘膜と異時多発癌の有無の関連に関する検討では，異時多発癌あり群のほうが，ESD後残存Barrett粘膜の最大長が有意に長く（3.3cm vs. 5.5cm，p＝0.038），切除検体の背景粘膜に占める腸上皮化生（IM）の割合も有意に高かった（42.0% vs. 8.0%，p＝0.047）．結論：LSBE由来の腺癌において，ESD後のBarrett粘膜長や，切除後検体のIM割合を詳細に評価することは，異時再発リスクを予測するうえで重要であり，その後の治療方針決定に寄与する可能性がある．

　Background：There is no consensus on appropriate surveillance after ESD（endoscopic submucosal dissection）since adenocarcinoma derived from LSBE（long segment Barrett's esophagus）is rare in Japan. We aim to evaluate risk factors for metachronous multiple cancers of LSBE-derived adenocarcinoma to determine an appropriate treatment strategy after ESD.

　Methods：We included 14 patients with LSBE-derived adenocarcinoma who underwent ESD at our hospital and were followed up for more than two years. The clinicopathological features between patients with and without metachronous multiple cancers were compared.

　Results：Among the patients, four（28.6%）had metachronous multiple cancers. There was no difference in the basal lesion characteristics between the two groups. However, there were some differences regarding the background mucosa around the lesion. The group with metachronous multiple cancers had longer maximum length of residual Barrett's mucosa after ESD（3.3cm vs. 5.5cm, p＝0.038）, and higher IM（intestinal metaplasia）rate on the background mucosa of resected specimen（42.0% vs. 8.0%, p＝0.047）than the group without metachronous multiple cancers.

　Conclusion：The length of Barrett's mucosa and the IM rate are important in predicting the risk of metachronous multiple cancers, and may contribute to the decision of appropriate treatment strategy after ESD in patients with LSBE-derived adenocarcinoma.