早期胃癌ESD適応拡大病変の長期予後

Long Term Survival of “Extended Indication” Cases of Early Gastric Cancer Treated with ESD

要旨　2000年1月から2004年5月までにESDを施行した早期胃癌232病変のうち，3年以上経過を追うことができた適応内群104例108病変・適応拡大群（分化型）71例74病変・適応拡大群（未分化型）5例5病変を対象とした．適応拡大群（分化型）は①M癌・腫瘍長径2.1cm以上・潰瘍非合併〔以下UL(－)〕・脈管侵襲陰性，②M癌・腫瘍長径3cm以下・潰瘍合併〔以下UL(＋)〕・脈管侵襲陰性，③SM1（粘膜筋板の下縁から500μm以下）癌・腫瘍長径3cm以下・ULの有無を問わないと定義し，適応拡大群（未分化型）はM癌・腫瘍長径2cm以下・UL(－)・脈管侵襲陰性と定義し，適応内群と適応拡大群（分化型），適応拡大群（未分化型）をそれぞれ比較検討した．一括完全切除率は適応内群92.6％，適応拡大群（分化型）90.5％，適応拡大群（未分化型）60.0％であり3群間に有意差はなかった．局所再発率は適応内群で0.9％，他群では0％であり3群間に有意差はなかった．遠隔転移は3群ともになかった．他病死を除く3年生存率はともに100％であった．適応拡大群（分化型）は適応内群の治療成績・長期予後と同等であり，内視鏡治療可能であると考えられた．また適応拡大群（未分化型）も適応拡大群（分化型）の治療成績・長期予後と同等であると考えられたが，症例数が少ないため今後，症例を重ね検討が必要と考えられた．

　Background：The indication for EMR (endoscopic mucosal resection) traditionally accepted by the Japanese Gastric Cancer Association is differentiated intramucosal adenocarcinoma of less than or equal to 20mm in diameter without ulceration. With the introduction of endoscopic submucosal dissection (ESD), an extended indication for treatment of early gastric cancer has been recently suggested.

　Purpose：The purpose of our study is to compare the outcomes of ESD for treatment of early gastric cancer following the expanded indication and that following the standard indication.

　Materials and methods：Of the 232 lesions of early gastric cancer treated with ESD at our hospital from January, 2000 to May, 2004, 187 lesions in 180 patients were followed up for over three years and were included in our analysis. These cases were divided into three groups：a standard indication group (104 patients with 108 lesions), an extended indication group for differentiated adenocarcinoma (71 patients with 74 lesions) and an extended indication group for undifferentiated adenocarcinoma (5 patients with 5 lesions). We defined the extended indication group for differentiated adenocarcinoma as (1) intramucosal cancer greater than 20mm in diameter without ulceration, (2) intramucosal cancer less than or equal to 30mm in diameter with ulceration, and (3) mucosal cancer with minimal submucosal invasion of 500 micrometer or less (SM1) and diameter of up to 30mm. We also defined an extended indication group for undifferentiated adenocarcinoma as intramucosal cancer of up to 20mm in diameter without ulceration. There were no significant differences in background among three groups. We compared with a standard indication group, the extended indication group for differentiated adenocarcinoma and the extended indication group for undifferentiated adenocarcinoma.

　Results：There was no significant difference among the three groups in complications. The complete en-bloc resection rate was 92.6％, 90.5％, 60.0％, respectively. The local recurrence rate was 0.9％, 0％, 0％, respectively. The three-year survival rate was 96.3％, 91.9％, 80.0％, respectively. And the cause-specific survival rate was 100％ in the three groups.

　Conclusion：The expanded indication for ESD of early gastric cancer appears very acceptable.