How Common is Appendiceal Cancer?
Appendiceal cancer is rare, occurring in approximately 0.9-1.0% of all appendectomies performed, with primary malignant tumors found in only 0.1% of appendectomies. 1, 2
Incidence and Epidemiological Data
The overall population incidence of appendiceal tumors is quite low:
Appendiceal neuroendocrine tumors (NETs) account for approximately 0.1-0.2 per 100,000 persons per year, with the incidence nearly doubling between 1975 and 2005. 3
Among all appendectomies, approximately 1% reveal any appendiceal tumor (benign or malignant), with the vast majority being carcinoid/neuroendocrine tumors (57% of appendiceal tumors), followed by benign tumors (16%), and primary malignant adenocarcinomas (27%). 2
True appendiceal adenocarcinomas represent only 0.08% of all cancers diagnosed, making them exceptionally rare. 4
The estimated annual incidence in the United States is approximately 3,000 new cases, though this likely underestimates true incidence due to diagnostic challenges and misclassification as colon or ovarian malignancies. 5
Clinical Context and Discovery
Most appendiceal cancers are discovered incidentally during appendectomy performed for suspected acute appendicitis (49% of cases), with only 9.5% being truly incidental findings during other procedures. 2
The rarity creates significant diagnostic challenges:
No disease-specific screening exists, and appendiceal tumors lack well-established risk factors or diagnostic imaging modalities that can detect them before symptoms develop. 5
Acute presentation mimicking appendicitis is the most common clinical scenario, making preoperative diagnosis nearly impossible in most cases. 2, 5
Important Clinical Pitfall
There is a remarkably high incidence of synchronous and metachronous colorectal cancer in patients with appendiceal tumors: 10% in carcinoid tumors, 33% in benign appendiceal tumors, and 89% in primary appendiceal malignancies. 2 This mandates colonoscopy as part of the workup for any appendiceal neoplasm. 6, 7