ESDによる表層拡大型食道癌の治療成績―多施設共同研究

Long-term Prognosis of Superficial Esophageal Cancers of at Least 50mm in Diameter Treated by Endoscopic Submucosal Dissection

要旨　2000年1月～2010年12月までの間に，対象施設で内視鏡的粘膜下層剝離術（ESD）が施行された腫瘍長径が50mm以上の表在型食道扁平上皮癌138例を対象とした．内訳は男性118名，女性20名と男性に多く，年齢中央値は69（42～88）歳であった．腫瘍長径が50～95mmと，大きな病変であるにもかかわらず，138例中137例で一括切除が施行され，分割切除はわずかに1例のみであった．また，一括完全切除率は88％（122/138）と，全食道ESDを対象とした既報と比し遜色のない結果であった．ESDの適応病変である深達度T1a-EP/LPMは，それぞれ30例，51例であり，全体の59％にとどまっていた．一方，相対適応であるT1a-MMが34例，T1b-SM1が5例と28％を占め，残りの18例（13％）はT1b-SM2であり，適応外病変であった．138例中，局所再発は1例のみで，51か月後に2型進行癌として再発を来した．138名中16名に追加治療が施行され，その治療法はRT 1例，CRT 15例で，外科切除例はなかった．追加治療が施行された16名は，観察期間中央値58（13～110）か月で，全例が無再発生存中であり，ESD＋RT or CRTの予後は，深達度にかかわらず極めて良好であった．一方，経過観察された122名中1名は予後調査ができず，4例が原病死，18例が他病死された．追加治療なしで経過観察され，予後が判明している121名のcause specific，all overの5年生存率はT1a-MM：90/71％，T1b-SM1：67/67％，T1b-SM2：90/67％であった．ESDは表層拡大型癌食道扁平上皮癌に対する，有効で，安全な治療法であった．一方，深達度T1a-MM以深の比率が約40％と高く，術前の深達度診断が残された課題である．

　［Aim］The aim of this study was to assess the efficacy of ESD（endoscopic submucosal dissection）for ECCS of at least 50 mm in diameter and to evaluate long-term prognosis after ESD.

　［Patients and methods］A total of 138 patients with superficial ECCS of at least 50mm in diameter treated by ESD were enrolled in this retrospective study. The patients were recruited from five territorial hospitals between 2000 and 2013 : Saku Central Hospital, Niigata University Hospital, Osaka Medical Center for Cancer and Cardiovascular Diseases, Shizuoka Cancer Center, and the National Cancer Center Hospital.

　Patients included 118 males and 20 females, and the median age was 69years（42～88years）. Cancers were located in the upper（11）, mid（81）, lower（43）, and abdominal（3）esophagus. Macroscopic types were 0-IIa（1）, IIb（12）, and IIc（125）. Additional treatments such as esophagectomy, CT（chemotherapy）, RT（radiation therapy）, and CRT（chemo/radiotherapy）were recommended for patients who had T1b ESCC.

　［Result 1. R0 resection rate and invasion depth］The en bloc resection rate was 99.3％（137/138）and the R0 resection rate was 88.4％（122/138）. There were no serious complications requiring surgical management. Invasion depth was sub-classified on the basis of the Japan Esophageal Society guidelines. The invasion depths for cancers classified as T1a-EP, T1a-LPM, T1a-MM, T1b-SM1（≦200μm）, and T1b-SM2 were 30, 51, 34, 5, and 18, respectively.

　［Result 2. Local recurrence］The local recurrence rate was 0.7％（1/138）. This patient had T1b-SM2 ESSC, but refused additional treatment. Local recurrence was diagnosed 51 months after ESD, and esophagectomy was performed.

　［Result 3. Prognosis］A total of 16 patients were treated with additional therapy（RT＝1, CRT＝15）, and currently, all of them are well with no evidence of recurrence. All other patients were followed up without additional therapy. Four of these patients died of esophageal cancer and 18 of other diseases. Cause-specific and overall 5-year survival rates for T1a-MM, T1b-SM1, and T1b-SM2 were 90/71％, 67/67％, and 90/67％, respectively.

　［Conclusion］ESD is a safe and effective treatment for ECCS of at least 50mm in diameter. The prognosis of T1a-EP and T1a-LPM is excellent. The prognosis of T1a-MM, T1b-SM1, and T1b-SM2 is also excellent when appropriate additional therapy is provided.