大腸腫瘍の内視鏡的切除後における局所再発の実態―切除断端からみた再発率とその経過

Risk of Local Recurrence after Endoscopic Resection of Colorectal Tumors

要旨　内視鏡的切除（ER）後に経過観察しえた径10mm以上の大腸腫瘍232例314病変（腺腫176病変，m癌121病変，sm₁癌17病変）を対象に，切除断端からみた遺残再発のリスク，再発の実態とその治療経過について検討した．局所再発は12病変にみられ，切除断端陰性の病変には再発はなく，全例，断端不明もしくは陽性であった．切除法でみると粘膜切除術において腫瘍径20mm以上で断端陰性例は減少したが，ポリペクトミーでは腫瘍径と切除断端には相関は認めなかった．再発病変における初回の肉眼型は結節集簇型6病変，Ⅱa3病変，Ⅰs（p）3病変であった，また一括切除例の局所再発は0.8％と低率で，再発病変の83.3％（10/12病変）が分割切除であった．再発病変の11病変は12か月以内に発見され，また11病変に対し追加治療（再ER3病変，焼灼5病変，外科手術3病変）を行い，全例完全治癒を得た．以上から，遺残再発のリスクは，①20mm以上の病変に対する粘膜切除術，②分割切除，③表面型あるいは結節集簇型腫瘍であり，これらの病変に対して厳重な経過観察が必要であると考えられた．

　We retrospectively analyzed follow-up colonoscopic data after endoscopic resection of colorectal tumors to evaluate the effectiveness of the the treatment. A total of 314 colorectal neoplasms more than 10 mm in size were removed from 232 patients. The neoplasms included 176 adenomas, 121 intramucosal carcinomas and 17 minimally invasive submucosal carcinomas. Tumor tissue on the cut margin was negative in 170 lesions (complete resection), positive in 37 lesions (positive cases), and unknown because of piecemeal resection in 107 lesions (unknown cases). The possibility of complete resection decreased when tumors more than 20 mm in size were treated by endoscopic mucosal resection. No correlation was found between the cut margin and tumor size when polypectomy was able to be carried out. We found 12 cases of local recurrence during the follow-up period of 2～96 (average 23) months, resulting in 73.8% and 91.8% of five-year non-recurrence in the positive and unknown cases, respectively. No recurrence has been noted in the cases of complete resection. The recurrence arose from six nodule aggregations, three type Ⅱa, and three type Ⅰs or Ⅰsp tumors, in which 10 aggregations had been removed by piecemeal resection except for two cases by enbloc resection. Over all, five-year non-recurrence was more frequent in enbloc resection than in piecemeal resection (96.9% vs. 82.0%). Most recurrence was detected within 12 months by follow-up colonoscopy. A complete cure was achieved in 11 recurrent cases by additional treatment consisting of endoscopic mucosal resection in three, electrocoagulation or LASER therapy in five, and the surgical resection in three cases. It is concluded that a close follow-up examination is required in cases of incomplete resection, particularly when ① a tumor more than 20 mm in size is treated by endoscopic mucosal resection, ② a tumor is removed by piecemeal resection, and ③ a tumor is type Ⅱa or comprised of nodule aggregations.