According to the American Cancer Society, the number of digestive system carcinoids has been increasing in recent years. About 8,000 new diagnoses are made annually. Although carcinoid tumors can appear anywhere in the body, the most common site is the lining of the gastrointestinal tract followed by the lungs.
Information. Carcinoid tumors are slow-growing cancers that can occur at different sites in the body. They are part of a class of tumors known as neuroendocrine tumors. These tumors arise from neuroendocrine cells, which have the characteristics of hormone-producing cells and nerve cells. Carcinoid tumors of the digestive tract are classified into three grades according to how likely they are to get bigger and move to other parts of the body. Grade 1 carcinoids are the slowest growing and least likely to spread while grade 3 carcinoids grow very fast and are quite likely to invade other organs. Lung carcinoid tumors are divided into two categories: typical and atypical. Like carcinoid tumors of the digestive tract, these categories represent how likely the cancer is to proliferate and spread. Typical carcinoids are the slowest-growing and least invasive while atypical carcinoids are the fastest growing and most intrusive.