Predicting the outcome of rectal carcinoid tumors

This study examined if the TNM staging system is useful for predicting the outcome of patients with rectal carcinoids (also known as neuroendocrine tumors).

Patients with rectal carcinoids have neuroendocrine tumors in the rectum. Neuroendocrine cells are important as they allow the nervous system (includes the brain and nerves) and organs to communicate. Communication happens when cells from the nervous system send chemical messages to neuroendocrine cells. The neuroendocrine cells then produce proteins (for example hormones) which enter the blood.

In general rectal carcinoid tumors do not tend to spread to other organs (metastasis). However, it has been reported that the tumors can spread to the lymph nodes. Similar to other types of rectal tumors, the TNM staging system is used when diagnosing the cancer. This system takes into account the size and depth of the tumor (T) and extent of cancer spread (nodes, N; and distant metastasis, M). Whether the TNM staging system is useful for predicting patient outcome is unclear. 

The authors examined the records from 122 patients who were treated for rectal carcinoids. 81.2% of patients had stage I tumors, 4.9% had stage II cancer, 11.5% had stage III tumors and 2.5% had stage IV tumors. Overall 88.4% of patients survived the first 5 years after diagnosis. Patients diagnosed with lower cancer stage had a better 5 year survival rate: 100% of patients with stage I, 80% of patients with stage II, 51.4% of patients with stage III and 0% of patients with stage IV cancer.

An initial diagnosis of stage I or II cancer also predicted a reduced chance of the cancer returning. 97.7% of patients with stage I, 62.5% of patients with stage II, 17.1% of patients with stage III and 0% of patients with stage IV cancer had no cancer at the end of 5 year follow-up.

The number of patients with cancer spreading to the lymph nodes was highest for patients diagnosed with the highest T scores: 84.6% of patients with T3 (largest), 0% of patients with T2, 16.7% of patients with T1b and 1.2% of patients with T1a (smallest). This indicated that the larger the tumor, the higher the risk that it would spread to the lymph  nodes. 

The authors concluded that the new TNM staging system is useful for predicting patient survival and risk of the cancer returning.

The small number of patients in this study limit how generalizable the results might be.