HUNTINGTON BEACH, CALIF. — Two proposed staging systems would divide patients who have rectal and colon carcinoid tumors, respectively, into statistically significant prognostic groups based on survival data, Dr. Christine S. Landry reported at the Academic Surgical Congress.
The proposed staging systems show overall survival at 5 years ranging from 100% for stage I rectal carcinoid tumors to 18% for stage IV, and from 96% for stage I colon carcinoid tumors to 20% for stage IV. No system is currently accepted for carcinoid tumors, according to the National Cancer Institute (NCI).
The proposed stages are based on an analysis of the NCI's Surveillance, Epidemiology, and End Results (SEER) database for 1977–2004. The SEER database includes 4,701 patients with rectal carcinoid tumors and 2,459 colon carcinoid tumors during that time period, said Dr. Landry of the University of Louisville (Ky.).
“Although rectal carcinoid tumors are often thought of as very slow-growing tumors, they do have significant malignant potential,” Dr. Landry said. “And the purpose of this study was to identify clinical pathological characteristics that predict overall prognosis as well as develop a staging system to help determine overall survival.” Similar considerations were at play in the study of colon carcinoid tumors.
Size of primary tumor, depth of invasion, lymph node metastasis, distant metastasis, and surgical resection were all significantly associated with prognosis for both rectal and colon carcinoid tumors in univariate analysis. Differences between the two tumors appeared in multivariate analysis.
For patients who have rectal carcinoid tumors, only the size of the primary tumor and the depth of invasion proved statistically significant prognostic indicators after controlling for the other factors. For patients who have colon carcinoid tumors, on the other hand, lymph node metastasis and distant metastasis were the only statistically significant independent prognostic indicators, she said.
Dr. Landry and her colleagues then looked at different combinations of these indicators to see how best to separate patients into different survival groups. For rectal carcinoid tumors, it proved best to divide patients into T stages based on a tumor size greater than or less than 2 cm and whether the depth of invasion went beyond the muscularis propria.
They proposed that tumors would be designated T1 if they had not grown beyond the muscularis propria and were less than 2 cm in diameter. Tumors would be designated T2 if they were beyond the muscularis propria and less than 2 cm in diameter or not beyond the muscularis propria and 2 cm or more in diameter. And tumors would be designated T3 if they were beyond the muscularis propria and 2 cm or more in diameter.
Colon carcinoid tumors, on the other hand, would be designated T1 if they were less than 2 cm in diameter, T2 if they were between the 2 cm and 4 cm in diameter, and T3 if they were 4 cm in diameter or more.
Both rectal and colon carcinoid tumors would be designated N0 if there was no nodal metastasis, N1 if there was nodal metastasis, M0 if there was no distant metastasis, and M1 if there was distant metastasis.
The investigators then analyzed different combinations of T, N, and M to determine how they should best be combined into staging systems. (See boxes.)
“Incorporating the staging systems into clinical practice will help us determine the best treatments for rectal [and colon] carcinoid tumors as well as predict overall survival,” Dr. Landry said.
Dr. Landry disclosed that she did not have any relevant financial relationships associated with her presentation.
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