Yutaka Inada1, Naohisa Yoshida2, Kohei Fukumoto3, Ryohei Hirose4, Ken Inoue4, Osamu Dohi4, Takaaki Murakami5, Kiyoshi Ogiso6, Akira Tomie7, Munehiro Kugai8, Hiroyuki Yoriki9, Yoshikazu Inagaki10, Daisuke Hasegawa11, Kotaro Okuda12, Takashi Okuda13, Yukiko Morinaga14, Mitsuo Kishimoto14, Yoshito Itoh4. 1. Department of Gastroenterology, Japanese Red Cross Kyoto Daiichi Hospital, Kyoto, Japan. 2. Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan. naohisa@koto.kpu-m.ac.jp. 3. Department of Gastroenterology, Nara City Hospital, Nara, Japan. 4. Department of Molecular Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan. 5. Department of Gastroenterology, Kyoto Kuramaguchi Medical Center, Kyoto, Japan. 6. Department of Gastroenterology, Osaka General Hospital of West Japan Railway Company, Osaka, Japan. 7. Department of Gastroenterology, Saiseikai Kyoto Hospital, Kyoto, Japan. 8. Department of Gastroenterology, Akashi City Hospital, Akashi, Hyogo, Japan. 9. Department of Gastroenterology, Otsu City Hospital, Otsu, Shiga, Japan. 10. Department of Gastroenterology, Nishijin Hospital, Kyoto, Japan. 11. Department of Gastroenterology, Ayabe City Hospital, Kyoto, Japan. 12. Department of Gastroenterology, Kyoto Kujo Hospital, Kyoto, Japan. 13. Department of Gastroenterology, Fukuchiyama City Hospital, Kyoto, Japan. 14. Department of Surgical Pathology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan.
Abstract
PURPOSE: For rectal neuroendocrine tumors (NETs) ≤ 10 mm, endoscopic resection is a standard treatment. However, there is no consensus whether additional surgery should be performed for patients at risk of lymph node metastasis (LNM) after endoscopic resection. The purpose of this study was to analyze the results of endoscopic resection and additional surgery of rectal NETs, thereby clarify the characteristics of cases with LNM. METHODS: This study was a multicenter retrospective cohort study conducted at 12 Japanese institutions. A total of 132 NETs ≤ 10 mm were analyzed regarding various therapeutic results. A comparative analysis was performed by dividing the cases into two groups that underwent additional surgery or not. Furthermore, the relationship between tumor size and LNM was examined. RESULTS: The endoscopic treatments were 12 endoscopic mucosal resections (EMR), 58 endoscopic submucosal resections with ligation (ESMR-L), 29 precutting EMRs, and 33 endoscopic submucosal dissections (ESD). The R0 resection rates of EMR were 41.7%, and compared to this rate, other three treatments were 86.2% (p < 0.001), 86.2% (p = 0.005), and 97.0% (p < 0.001), respectively. There were 41 non-curative cases (31.1%), and 13 had undergone additional surgery. Then, LNM was observed in 4 of the 13 patients, with an overall rate of LNM of 3.0% (4/132). The rate of positive lymphatic invasion and the rate of LNM by tumor size ≤ 6 mm and 7-10 mm were 9.7 vs. 15.4% (p = 0.375) and 0 vs. 10.3% (p = 0.007). CONCLUSIONS: A multicenter study revealed the priority of each endoscopic resection and the low rate of LNM for rectal NETs ≤ 6 mm.
PURPOSE: For rectal neuroendocrine tumors (NETs) ≤ 10 mm, endoscopic resection is a standard treatment. However, there is no consensus whether additional surgery should be performed for patients at risk of lymph node metastasis (LNM) after endoscopic resection. The purpose of this study was to analyze the results of endoscopic resection and additional surgery of rectal NETs, thereby clarify the characteristics of cases with LNM. METHODS: This study was a multicenter retrospective cohort study conducted at 12 Japanese institutions. A total of 132 NETs ≤ 10 mm were analyzed regarding various therapeutic results. A comparative analysis was performed by dividing the cases into two groups that underwent additional surgery or not. Furthermore, the relationship between tumor size and LNM was examined. RESULTS: The endoscopic treatments were 12 endoscopic mucosal resections (EMR), 58 endoscopic submucosal resections with ligation (ESMR-L), 29 precutting EMRs, and 33 endoscopic submucosal dissections (ESD). The R0 resection rates of EMR were 41.7%, and compared to this rate, other three treatments were 86.2% (p < 0.001), 86.2% (p = 0.005), and 97.0% (p < 0.001), respectively. There were 41 non-curative cases (31.1%), and 13 had undergone additional surgery. Then, LNM was observed in 4 of the 13 patients, with an overall rate of LNM of 3.0% (4/132). The rate of positive lymphatic invasion and the rate of LNM by tumor size ≤ 6 mm and 7-10 mm were 9.7 vs. 15.4% (p = 0.375) and 0 vs. 10.3% (p = 0.007). CONCLUSIONS: A multicenter study revealed the priority of each endoscopic resection and the low rate of LNM for rectal NETs ≤ 6 mm.