表在性の中・下咽頭癌の治療

Endoscopic Strategy for Superficial Middle and Hypopharyngeal Tumors

要旨　中・下咽頭における扁平上皮癌の拡大内視鏡観察所見が解明されるにつれて，多数の表在性の中・下咽頭癌が発見されるようになってきた．通常内視鏡で発赤部を見い出し（NBIでは，発赤調の病変部はbrown spotとして認識される），拡大内視鏡所見IPCLパターン分類でtype IVやV-1を認めれば，上皮内癌を含めた腫瘍性病変の可能性が高まる．「頭頸部癌取扱い規約」の0期（TisN0M0）の病変を認めれば，完全生検の意味でもEMRを施行している．広範囲のEMRも技術的に可能であるが，EMRの影響が喉頭に及ぶと考えた場合には，気道の予防的確保の意味でも，一時的な気管内挿管や気管切開術が必要である．これまでに30例に中・下咽頭腫瘍性病変の内視鏡的切除術を行っているが，特記すべき合併症を認めていない．スクリーニング内視鏡において，より早期の癌，さらには微小癌を見つけ出すことは，治療侵襲の軽減，ひいては患者利益に直結するものと考えられる．

　Superficial lesions in the middle and hypopharynx were firstly detected as the same kind of lesions as superficial esophageal cancer. Most of the lesions were observed as reddish patches and the others were detected as whitish slight elevations. Both kinds of lesions were confirmed with conventional bite biopsy.

　Magnifying endoscopy revealed precise characteristics of the minute lesions in the pharynx. IPCL type IV and V have, to a great extent, the characteristics of high grade intraepithelial neoplasia which includes carcinoma in situ. (Similar characteristics are also found in esophageal cancer) High resolution endoscopy with magnification enables the detection of high grade intraepithelial neoplasiia, even less than 2 mm in diameter.

　When we suspect carcinoma in situ with no lymph node metastasis, EMR becomes the first line of treatment, which enables precise histopathological analysis. In order to avoid respiratory insufficiency just after the treatment, general anesthesia under intratracheal intubation becomes mandatory when the treatment area involves a laryngeal lesion. Major mucosal injury to the tracheal area demands temporay tracheostomy.

　As the laryngo-pharyngeal region is structurally complicated, EMR using small caliber endoscopy is necessary.