Clinical experience with neuroendocrine rectal tumors.

Abstract

611 Background: Carcinoids are heterogeneous neuroendocrine tumors with malignant potential. The rectum is the third most common location for gastrointestinal carcinoids after small bowel and colon. Due to their rarity, the characteristics and behavior of this unusual malignancy remain unclear. Methods: Retrospective review of the clinicopathologic features of patients treated for carcinoid tumors of the rectum. Results: A single institute's tumor registry was retrospectively queried, identifying nine patients with rectal carcinoid tumors over a 10-year period. The mean age at diagnosis was 57.6 years. Four of the nine patients were female. Presenting symptoms included abdominal pain in five patients, rectal bleeding in two patients and a change in bowel habits in one patient. As previously reported, no patient had symptoms consistent with carcinoid syndrome. The rectal tumor size was > 2 cm in five patients. The rectal tumor was located in the lower third of the rectum in three cases (< 5 cm from anal verge) whereas three were in the middle third (6-11 cm) and two in the upper third (11-15 cm). Four of the tumors were well differentiated tumors (grade 1), 1 was atypical carcinoid or moderately differentiated tumors (grade 2), and 4 were poorly differentiated tumors (grade 3) according to the SEER. Initially, 5/9 patients had distant metastasis. As an initial site of metastasis, the liver was the most common site (4/5 patients, 80%). Five patients underwent surgical treatment of their rectal tumor, two with endoscopic transanal resection whereas 3 patients had a low anterior resection (LAR). Three patients received chemotherapy treatment only in the metastatic setting and one patient received chemotherapy and radiotherapy as palliative treatment. Of the nine patients, five had progressive disease after initial treatment. With a median follow-up of 14 months, the overall survival of the entire population was 13.4 months. Conclusions: Neuroendocrine carcinomas of rectum are uncommon. Only small rectal carcinoids can be safely managed and surgery represents the treatment that can offer a greater chance of survival to these patients. Larger primary tumors have a high tendency to spread early. They are associated with aggressive behavior, resistance to chemotherapy and poor prognosis. No significant financial relationships to disclose.