Surgical treatment options for rectal carcinoid cancer: local versus low radical excision.

R ECTAL CARCINOIDS ARE rare and their biologic behavior and optimal surgical treatment remain poorly defined. Classically, primary tumors less than 2 cm were assumed to be indolent and were treated by transanal excision. We hypothesized that rectal carcinoids are more malignant than previously described and tumors less that 2 cm may warrant more aggressive surgery. The charts of 62 consecutive patients with rectal carcinoids seen at our institution between October 2006 and August 2011 were reviewed. The primary tumor size, extent of disease, and survival data were analyzed. The primary tumor size and the incidence of lymph node metastases were available for 60 of 62 patients and was: less than 1 cm: two of 26 (8%); 1.1 to 2 cm: nine of 13 (69%); 2.1 to 3 cm: four of five (80%), greater than 3 cm: seven of 12 (58%); and multiple primaries: two of four (50%). Small (less than 2 cm) rectal carcinoids have a higher incidence of nodal positivity than previously described. Based on our survival data, we believe that tumors larger than 1 cm should be considered for a low anterior resection with total mesorectal excision as their initial definitive treatment. For tumors less than 1 cm, treatment should be individualized. RECTAL CARCINOIDS ARE relatively rare, with a reported incidence of one in every 100,000 people.1 However, recent reports have indicated that this incidence is on the rise.2 The 5-year survival rate for all rectal carcinoid tumors has been reported to be as high as 88 per cent, and these high survival rates were attributed to the fact that most rectal carcinoids are small and present with localized disease.3, 4 The incidence of lymph node metastasis for rectal primaries less than 1 cm has been reported to be less than 3 per cent. For primaries between 1 and 2 cm, nodal positivity has generally been reported between 10 and 15 per cent,4–9 but has recently been reported as high as 31 per cent.10 In contrast, the nodal positivity rate for tumors greater than 2 cm is classically reported as 80 per cent.3, 4, 6–9 Based on this, the treatment guidelines for rectal carcinoids universally agree that tumors greater than 2 cm demand a formal oncological operation such as a low anterior resection (LAR) with total mesorectal excision (TME) or abdominal–perineal resection (APR) with TME. For local rectal carcinoids, less than 1 cm in size, without evidence of lymphatic involvement on endoscopic ultrasound, a transanal surgical or endoscopic excision has been embraced as the standard in the literature and by the major organizational guidelines: European Neuroendocrine Tumor Society, North American Neuroendocrine Tumor Society, National Cancer Institute, and National Comprehensive Cancer Network.4, 6–9 In contrast, the treatment for rectal carcinoids from 1 to 2 cm is a matter of intense debate. Some authors believe that these intermediate-sized lesions will behave in an indolent manner. These authors recommend a conservative, nonaggressive approach to their resection.4–10 However, we have observed relatively poor clinical outcomes in this intermediate rectal carcinoid population. Based on our clinical experiences in a large tertiary referral center for neuroendocrine tumors (NETs), we conducted a formal review to better define the clinical impact that tumor size has on nodal positivity and the overall survival rate for this rare malignancy. We hypothesized that the malignancy potential of rectal carcinoids has been underestimated and that smalland intermediate-sized rectal carcinoids may warrant more aggressive surgery than what has been traditionally recommended.