Carcinoid tumors have been called "cancers in slow motion" because they grow slowly. They are also less likely than other tumors to spread (metastasize) to other parts of the body. However, this is not always the case. Sometimes, they grow and spread rather quickly.
Most carcinoid tumors start in the small intestine, but about 25% of them begin in the lungs. They account for only a small percentage of all lung cancers. Some carcinoid tumors, especially those arising from the gastrointestinal tract or the appendix, produce hormones that can cause a number of symptoms. Carcinoid tumors in the lung are much less likely to produce hormones.
There are two types of carcinoid tumors of the lung: typical and atypical. Typical carcinoid tumors are about nine times more common than atypical carcinoid tumors. Typical carcinoid tumors are also less likely to spread beyond the lungs.
Carcinoid tumors of the lung occur equally in women and men, usually between ages 45 and 55.