What are the current NCCN guidelines for staging, treatment, and surveillance of a patient with a prior malignant appendix neoplasm?

Management of Malignant Appendiceal Neoplasms: NCCN Guidelines

Immediate Diagnostic Workup

When appendiceal adenocarcinoma is discovered, obtain abdominal/pelvic CT or MRI with IV contrast, chest CT, baseline CEA level, and colonoscopy to exclude synchronous colorectal neoplasia. 1

• Colonoscopy is critical because patients with primary malignant appendiceal adenocarcinomas carry an 89% risk of synchronous or metachronous colorectal cancer 2
• Histopathological classification must be completed immediately to determine the appropriate surgical approach 1
• At least 12 lymph nodes must be examined in the surgical specimen for adequate staging 1

Surgical Management Algorithm by Tumor Size and Features

For Adenocarcinomas <1 cm

• Simple appendectomy alone is sufficient only for well-differentiated tumors <1 cm confined to the appendix without adverse features 1, 3

For Adenocarcinomas 1-2 cm

• Right hemicolectomy should be performed if ANY high-risk features are present: 1
  • Breach of serosal surface 1, 3
  • Mesoappendiceal invasion >3 mm 1, 3
  • Location at base of appendix 1, 3
  • Lymphovascular invasion 1
  • Incomplete resection margins 1
  • Poorly differentiated histology 1

For Adenocarcinomas ≥2 cm

• Right hemicolectomy with regional lymphadenectomy is mandatory, even without obvious malignant features, due to significantly higher risk of lymph node metastases 1, 3

Critical Exception: Goblet Cell Adenocarcinoma

Goblet cell adenocarcinoma (adenocarcinoid) must be managed according to colon cancer protocols, NOT neuroendocrine tumor protocols, and right hemicolectomy is always required regardless of size. 1

• These tumors behave much more aggressively with adenocarcinoma-like biology 1, 4
• They exhibit unpredictable behavior even in early stages with potential for local recurrence and delayed metastases 4

Adjuvant Chemotherapy

For node-positive disease (Stage III) or peritoneal involvement, use FOLFOX (5-FU/leucovorin/oxaliplatin) as preferred adjuvant chemotherapy, with capecitabine ± oxaliplatin as an alternative. 1

• Systemic therapy for advanced appendiceal adenocarcinoma follows colorectal cancer regimens 1, 5
• Response rates of 39% and median overall survival of 2.1 years are achievable with modern chemotherapy regimens 5
• Poor prognostic factors include nonmucinous histology, high-grade tumors, and history of nondebulking surgery 5

Surveillance Protocol

Follow colorectal cancer surveillance protocols with the following schedule: 1

• History and physical examination every 3-6 months for 2 years, then every 6 months for years 3-5 1
• CEA monitoring at each visit 1
• CT chest/abdomen/pelvis every 6-12 months for 5 years 1
• Colonoscopy at 1 year, then per standard colorectal cancer guidelines 1

Common Pitfalls to Avoid

• Do not treat goblet cell carcinomas as neuroendocrine tumors—they require aggressive surgical resection like adenocarcinomas 1, 4
• Do not skip colonoscopy—the extremely high rate of synchronous colorectal cancer (89% for malignant appendiceal adenocarcinomas) makes this essential 2
• Do not perform simple appendectomy for tumors ≥2 cm—lymph node metastases are significantly more common and right hemicolectomy is mandatory 1, 3
• Lifelong surveillance is warranted for goblet cell carcinomas due to unpredictable behavior and potential for delayed metastases 4