Obturator canal lymph node metastasis from rectal carcinoid tumor

• Published in: Journal of clinical oncology Vol. 30; no. 4_suppl; p. 440
• Main Authors: Wang, Yi-Zarn, Hall, Michael Anthony
• Format: Journal Article
• Language: English
• Published: 01.02.2012
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/jco.2012.30.4_suppl.440

Abstract only 440 Background: The optimal treatment option for rectal carcinoid tumor remains unsettled. Trans-anal excision has been accepted for small tumors (< 1-2 cm in size) without lymph node involvement. Larger tumors, and those with lymph node metastasis, however, are usually treated via low anterior resection (LAR) with total mesorectal excision (TME). Midgut carcinoid tumors have been found to have the tendency to obstruct lymphatic flow and create a detour in lymphatic passage. We hypothesize that rectal carcinoid may have similar potential to develop alternative lymphatic pathways outside of the mesorectal envelope, thus escaping surgical removal with traditional TME. Methods: A retrospective chart review of rectal carcinoid patients who underwent radical LAR with TME between 2006 and 2011 was conducted to determine if any extra-mesorectal metastasis had occurred. Results: 19 patients who underwent LAR with TME for rectal carcinoid were identified. 14 patients had radio-guided surgery (RGS). 12 of which, were injected with TC-99 intra-operatively and 2 had a preoperative injection of In-111 for octreotide scan. 6 of the 19 patients (31.5%) were found to have obturator canal lymph node metastasis, confirmed by final pathologic review. 5 of these 6 patients had the nodal metastasis to the right obturator canal. Of note, 4 of the 6 patients complained of debilitating foot and medial thigh pain on the affected side, with complete symptom resolution after surgical excision. Conclusions: Up to 31.5% of rectal carcinoid patients can have extra-mesorectal lymph node metastasis that could easily be missed by the traditional TME. Preoperative octreotide scanning with In-111 injection or intra-operative Tc-99 peri-tumor injection, with concomitant RGS can easily identify and remove such metastasis. Symptomatic improvement can be accomplished with its removal. The effect of such extra-mesorectal metastasis on patients’ long term or disease free survival is yet to be determined.