From the Guidelines
Appendix cancer is rare, with an incidence of approximately 0.15 to 0.9 cases per 100,000 people per year. This represents less than 1% of all gastrointestinal cancers diagnosed in the United States annually. The most common type is appendiceal neuroendocrine tumors (carcinoids), accounting for about 50-75% of all appendix cancers, followed by adenocarcinomas.
Key Points
- The incidence appears to be increasing slightly over time, though this may partly reflect improved detection through more frequent imaging and surgical procedures 1.
- Appendix cancer is typically discovered incidentally during appendectomy procedures performed for suspected appendicitis, as it rarely causes specific symptoms in early stages.
- The disease is more commonly diagnosed in adults between 50 and 70 years of age, though it can occur at any age.
- Risk factors remain poorly understood, with no clear genetic or environmental causes identified.
- Due to its rarity, appendix cancer may be underreported in cancer registries, potentially leading to underestimation of its true incidence.
Management
- For tumors less than 1 cm in size, simple appendectomy is usually sufficient, while for tumors greater than 2 cm in size, right hemicolectomy is the treatment of choice 1.
- For tumors 1-2 cm in size, any of the following mandates right hemicolectomy: serosal breach by tumor, cellular atypia, invasion of mesoappendix.
Diagnosis and Treatment
- Patients with an incomplete resection or tumors smaller than 2 cm are at risk for locoregional or distant metastases, and should be staged with abdominal/pelvic CT or MRI scans 1.
- If no distant disease is identified, they should undergo reexploration with a right hemicolectomy.
From the Research
Incidence of Appendix Cancer
- The incidence of appendix cancer is relatively low, with a reported age-adjusted incidence of 0.12 cases per 1,000 people per year 2.
- Carcinoid tumors of the appendix are the most common primary malignant lesion of the appendix, found in as few as 0.3-0.9% of appendicectomy specimens 3.
- Goblet cell carcinoids of the appendix are rare, with an annual population incidence of 0.66/1,000 4.
Types of Appendix Cancer
- Carcinoids of the appendix are classified as "malignant carcinoid" and are rarely suspected before surgery 2.
- Goblet cell carcinoid tumors exhibit histologic features of both adenocarcinomas and neuroendocrine tumors 5.
- Other types of appendix cancer include colonic type adenocarcinoma, mucinous adenocarcinoma, signet ring cell carcinoma 2.