[Therapeutic strategy for neuroendocrine tumor of the rectum]

The clinicopathological features of neuroendocrine tumor (NET) of the rectum were retrospectively analyzed in 25 patients( 17 men and 8 women; mean age, 57 years[ 30-78 years]) at Tohoku University Hospital from January 1998 to December 2012. The average diameter of 25 tumors was 15 mm (5-70 mm). Local resections and rectal resections with lymph node dissection were performed in 16 and 9 tumors, respectively. Three of the 9 tumors had lymph node metastases (33%), including 2 tumors with a diameter of 10 mm. In a median follow-up of 48 months, tumor recurrence was observed in 3 of 25 patients( 12%); local recurrence was observed in 1 patient; and liver metastasis was observed in 2 patients. Of the 2 patients with liver metastasis, liver metastasis recurred in a patient whose primary tumor, with a diameter of 10 mm, had been locally resected 40 months ago. According to histopathological analysis, 3 primary tumors with local recurrence or liver metastasis were categorized as G2 or G3 according to the World Health Organization (WHO) classification. Tumors with a diameter of ≥10 mm, in principle, may be removed by rectal resection with lymph node dissection. However, histopathological findings such as a proliferation of tumor cells should also be taken into consideration when deciding the treatment strategy for rectal NET.