Background: The lack of a clinically relevant staging system for carcinoid tumors of the rectum creates a persistent challenge for clinicians trying to provide patients with meaningful prognostic information. The purpose of this study was to identify the clinicopathologic factors that affect survival for patients diagnosed with carcinoid of the rectum, and to use this information to create a staging system.
Methods: A search of 15,983 patients with carcinoid tumors from the National Cancer Institute's SEER (Surveillance Epidemiology and End Results) database identified 4701 patients with rectal carcinoid tumors from 1973 to 2004. Patients were analyzed according to various clinicopathologic factors and a tumor (T1, T2, T3), lymph node (N0, N1), and metastasis (M0, M1) staging system was created according to these parameters. The staging system was developed using log rank tests and the Cox proportional hazards model.
Results: Of the 4701 patients, 2329 females and 2372 males were identified with a median age of 56 years (14-94). Median size of primary tumor was 0.6 cm (0.1-25). Lymph node metastasis was found in 111 (4%), and distant metastatic disease was present in 97 (2.4%) patients. Rectal carcinoid was the only primary malignancy in 82% of patients; 17% presented with 1 additional primary malignancy, and 1% had two or more additional malignancies. Age, size, depth of invasion, lymph node involvement, and distant metastasis were significant predictors of survival. Four stages were created according to statistically significant prognostic factors: 83% of patients were classified into Stage I, 6.5% into Stage II, 2.8% into Stage III, and 7.4% into Stage IV. Five-year survival rates were 97%, 84%, 27%, and 20% for Stages I through IV, respectively.
Conclusion: The newly developed TNM staging system accurately discriminates prognosis for carcinoid tumors of the rectum. Size of primary tumor, depth of invasion, lymph node involvement, and distant metastasis have the greatest impact on survival. Incorporation of this staging system into clinical practice will allow better study of outcomes and development of stage-specific treatment recommendations.