There are several different kinds of appendix cancer, classified by the types of cells inside the tumors:
Carcinoid tumors (also called neuroendocrine tumors)
About 50 percent of appendix cancers are carcinoid, or neuroendocrine tumors.  These tumors are usually small and often can be treated with an appendectomy (removal of the appendix). In some cases, more extensive surgery may be necessary. Carcinoid tumors of the appendix are most often seen in women who are in their forties.
Adenocarcinomas
Adenocarcinomas in the appendix tend to be aggressive, spreading to lymph nodes and traveling — a process known as metastasis — to other parts of the body.
In some cases, a patient may be diagnosed with a hybrid of a carcinoid and an adenocarcinoma (called goblet cell carcinoid or ex-goblet adenocarcinoma). This tumor has a high propensity to metastasize.
Pseudomyxoma peritonei (PMP)
This rare type of appendix cancer usually begins in the inner lining of the appendix and can spread into the abdomen. PMP appendix cancer is seen in both men and women who are in their fifties.