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Epidemiology of Appendiceal Cancer (additions)

(A study of primary malignancies in the United States found a rate of 0.12 cases per 1,000,000 population per year. Carcinoids that were not identified as malignant were not included in this data. Carcinoid is found in roughly 1 in 300-400 appendectomies for acute appendicitis. A Hong Kong case series of 1492 appendectomies identified 17 neoplasms. Eight were carcinoids without specification of malignant features. Three cases of adenocarcinoma, and one each of cystadenocarcinoma, pseudomyxoma peritonei, and metastasic carcinoma were identified. The remaining tumors were benign. Carcinoid tumors are the most common tumors of the appendix.)

In a systematic literature review where 4765 appendiceal cancer patients were identified, the incidences of appendiceal cancer were shown to have increased regardless of the type of tumor, age, sex, and stage of appendiceal cancer. The most common forms were mucinous adenocarcinoma's, carcinoids, adenocarcinoma-not otherwise specified (NOS), and signet ring cell adenocarcinoma listed from highest to lowest incidence. Roughly 75% of appendiceal cases listed in the review had some form of metastases occurring. No observed trends have been noticed as to why this increase is occurring. One theory proposed is the increased use of computed tomography imaging in emergency departments since the early 1990's allowing for detection to occur before a surgery may be performed.

A specific subgroup under neoplasias that occur in the appendix are called Neuroendocrine Tumors (NETs). Incidence rates among neuroendocrine tumors occur at about .15 per 100,000 per year. This subgroup makes up a large amount of neoplasias both malignant and benign. Almost 3 out of 4 of these tumors are associated with the region at the end of the appendix, and tend to be diagnosed in the 4th to 5th decades in life. Both women and Caucasian individuals show a minor prevalence regarding Neuroendocrine tumor diagnosis without an explanation. Prognosis of 5 year survival rates of neuroendocrine tumors averages between 70-80% for typical cases. Advanced cases for 5 year survival range from 12-28%. Neuroendocrine tumors have higher survival rates compared to the other tumors that occur in the appendix such as Globet cell carcinoids or mucinous adenocarcinomas, and normally are found during appendectomies when acute appendicitis in a patient is suspected.