Tumor size is irrelevant in predicting malignant potential of carcinoid tumors of the rectum

Abstract

The malignant potential and prognosis of rectal carcinoids are said to be related to tumor size. Our study assessed if size could predict the malignant potential and hence its management. All patients in the Department of Colorectal Surgery, Singapore General Hospital, who underwent surgery for rectal carcinoid tumors between February 1991 and September 2000 were analyzed. Twenty patients (11 men), median age 48 years (range, 33-77 years) were studied. Median follow-up was 40 months (range, 5-120 months). The median tumor diameter was 2.5 cm (range, 0.1-5.0 cm). Eleven patients underwent radical resection and 9 patients had local resection for a presumed benign tumor. Morbidity was 15% and postoperative death was 5%. Overall median survival was 24 months (range, 5-120 months). One patient had an anterior resection for rectal adenocarcinoma but had an incidental 0.1-cm carcinoid tumor near the resection margin which on histology was found to have carcinoid tumor metastasis to 2 out of 12 lymph nodes. In conclusion, tumor size cannot predict malignant potential as even small tumors (<1 cm) can be malignant. Accurate preoperative staging with radical surgery may be required.

The Novel WHO 2010 Classification for Gastrointestinal Neuroendocrine Tumours Correlates Well with the Metastatic Potential of Rectal Neuroendocrine Tumours

“…However, 4 of 8 metastasised tumours were smaller than 2 cm. Our findings are consistent with those of Heah et al [23] and Koura et al [21]. …”

Atypical endoscopic features can be associated with metastasis in rectal carcinoid tumors

“…Tumor size has long been regarded as a reliable and easily obtained parameter that correlates with metastasis. However, even small tumors (\1 cm) can be malignant [8][9][10], illustrating that the risk of metastasis is not governed by primary tumor size alone. Fahy et al reported that the risk stratification score using tumor size, invasion depth, and histopathological features could accurately predict the outcome [1].…”

Clinicopathological characteristics of rectal carcinoid patients undergoing surgical resection

“…However, large numbers of cases in those studies received endoscopic treatment. For patients with small rectal carcinoids who underwent endoscopic treatment, the rate of lymph node metastasis is reported to be low (22,25,26). By contrast, the rate of lymph node metastasis from a small rectal carcinoid in patients who underwent surgery with a lymphadenectomy has been reported to be 66% (27).…”