Current Status of Surgery for Colorectal Neuroendocrine Tumor

• Published in: Nippon Daicho Komonbyo Gakkai Zasshi Vol. 73; no. 10; pp. 467 - 474
• Main Authors: Takahashi, Keiichi, Yamaguchi, Tatsuro, Natsume, Souichiro, Nakamori, Sakiko, Ono, Tomoyuki, Takao, Misato, Nakano, Daisuke
• Format: Journal Article
• Language: Japanese; English
• Published: The Japan Society of Coloproctology 2020
• Subjects: colorectal NET; local excision; lymph node metastasis; predictive risk factors of the lymph node metastasis; surgery
• ISSN: 0047-1801; 1882-9619
• DOI: 10.3862/jcoloproctology.73.467

It is sometimes difficult to choose local excision or bowel resection with lymph node dissection as the surgical treatment for colorectal NET (neuroendocrine tumor). The latter surgery is necessary when the risk of lymph node metastasis is high. The size of the metastatic lymph node for rectal NET on the preoperative CT image is smaller than that of rectal cancer. It is very difficult to identify the true metastatic lymph node accurately. We analyzed 387 cases of colorectal NET from a nationwide retrospective cohort to determine the predictive risk factors of lymph node metastasis.Five predictive risk factors were found: tumor size (≥10 mm), superficial depressed type, NETG2, depth of invasion (proper muscle or deeper) and lympho-vascular invasion. The rates of lymph node metastasis by the number of these risk factors were as follows: no factor: 0.7%, 1 factor: 19.1%, 2 factors: 20.7%, 3 factors: 61.9%, 4 factors: 75.0% and 5 factors: 75.0%. Cases with more than two factors showed the highest rate of lymph node metastasis. It is considered that the type of surgery should be decided based on these five predictive risk factors.