Surveillance Strategy for Rectal Neuroendocrine Tumors According to Recurrence Risk Stratification

Rectal neuroendocrine tumors (NETs) have been increasing in incidence. However, the recommendations for disease surveillance after tumor resection have not been well established. We evaluated the long-term outcomes of rectal NETs and surveillance strategies according to recurrence risk stratification. From January 2000 to July 2011, 188 patients diagnosed with rectal NETs were included in this study. Patient characteristics, treatment methods, recurrence rates, risk factors of recurrence, and surveillance schedules were analyzed. The male-to-female ratio was 1.29:1 and the mean age at diagnosis was 50.6 years. The mean tumor size was 6.5 (range 1-30) mm. A total of 144 patients (76.6 %) were treated with endoscopic resection, and 44 patients (23.4 %) were treated with surgical resection as the initial treatment. During the follow-up period, ten patients (5.3 %) had disease recurrence, including one case of local recurrence and nine cases of recurrence at a distant site. Tumor size of > 10 mm, invasion of the muscularis propria, increased mitotic index, lymphovascular invasion, and regional lymph node metastases were statistically significant predictors of recurrence by univariate analysis. Among the 152 patients without risk factors of recurrence, only one patient who underwent transanal resection had a local recurrence at 15 months after surgery. Our patients with rectal NETs showed favorable clinical outcomes and had a low rate of recurrence. Intensive surveillance with endoscopy or imaging study may not be required in patients without risk factors for recurrence.