To study the clinicopathologic characteristics and prognosis of rectal neuroendocrine neoplasms (NENs) .

From January 2000 to May 2017, 84 patients were diagnosed as NENs by pathology and underwent surgical treatment in Peking University First Hospital. Their clinicopathological characteristics, surgial options and prognosis were analyzed retrospectively.

Among these 84 cases, 67 cases were NET G1, 6 cases were NET G2, 10 cases were NEC G3 and 1 case was MANEC G3. The median size was 0.8 (0.2 to 18.0) cm. There were 60 cases of stageⅠ, 2 cases of stageⅡ, 12 cases of stage Ⅲ, 10 cases of stage Ⅳ. Forty-nine patients accepted examinations because of non-specific symptoms, including altered bowel habits (22/49) , bloody stool (19/49) and abdominal pain (10/49) ; the other 35 cases including 2 patients with liver metastasis were diagnosed by endoscopy or CT during routine physical examination. Forty-four patients received endoscopic ultrasonography (EUS) with 100% of sensitivity and 90.9% of accuracy. Among 20 cases (23.8%) with lymph node metastasis (all ≥T2 stage) , 12 cases were NET G1 and G2 (1 case of multiple NET G1) and 8 cases were NEC G3 and MANEC G3. The lymph node metastasis rate of stage T1 NET G1 and G2 was lower than that of stage T2 to T4 NET G1 and G2, also lower than that of NEC G3 and MANEC G3 (all P= 0.000) , however, stage T2 to T4 NET G1 and G2 showed the similar rate of lymph node metastasis with NEC G3 and MANCE G3 (P > 0.05) . Synchronously distant metastasis was found in 10 (11.9%) patients at the first diagnosis, and ovarian metastasis was found in 1 case 9 years after curative resection of rectal NEN. Among 81 patients receiving operation, 57 patients underwent endoscopic mucosal resection (56 patients of stage T1 NET G1 and G2) ; 3 patients local excision without lymph node dissection; 13 patients curative resection; 1 patient curative resection with liver metastasis resection; 6 patients palliative surgery and 1 patient metastatic lesion resection only. Overall follw-up time was 1 month to 169 months, and the 3-and 5-year survival rates were 87.7% and 79.7% respectively. No recurrence or metastasis was observed in all the 62 patients with T1 G1 and G2, including 56 cases of ESD, 3 cases of local excision, 3 cases of curative resection, whose 3-year and 5-year survival rates were both 96%. The prognosis was closely associated with grade and stage of NENs (all P= 0.000) .

The early symptoms of rectal NENs are insidious and atypical, therefore some patients are diagnosed as stage Ⅱ or higher at their first consultation. ESD is safe and effective for NET G1 and G2. The prognosis depends on grade and stage of NENs.

Neuroendocrine neoplasms; Clinicopathologic significance; Surgical treatment; Prognosis