What is the primary treatment for adenocarcinoma of the appendix?

Primary Treatment for Adenocarcinoma of the Appendix

The primary treatment for adenocarcinoma of the appendix is right hemicolectomy with regional lymphadenectomy, which provides superior survival outcomes compared to appendectomy alone and should be performed even as a secondary procedure if the initial diagnosis was made after simple appendectomy. 1

Surgical Management Based on Tumor Characteristics

For Small, Low-Risk Tumors

• Simple appendectomy is sufficient only for well-differentiated tumors <1 cm confined to the appendix with no adverse features, as this is likely curative 2, 3
• This limited approach is appropriate when there is no lymphovascular invasion, no mesoappendiceal invasion, and the tumor does not breach the serosal surface 2

For Tumors ≥2 cm or High-Risk Features

• Right hemicolectomy with regional lymphadenectomy is indicated for all tumors ≥2 cm, even without obvious malignant features, due to higher risk of lymph node metastases (present in up to 38% when secondary resection is performed) 2, 1
• Right hemicolectomy should also be performed for tumors of any size with high-risk features, including:
  • Breach of the serosal surface 2, 3
  • Mesoappendiceal invasion >3 mm 2, 3
  • Location at the base of the appendix 2, 3
  • Lymphovascular invasion 2
  • Incomplete resection margins 2

Evidence Supporting Right Hemicolectomy

• Right hemicolectomy provides significantly better survival than appendectomy alone (68% vs. 20% 5-year survival, p<0.001) 1
• Secondary right hemicolectomy results in upstaging in 38% of patients, identifying previously undetected lymph node involvement 1
• All patients who underwent right hemicolectomy in one series remained alive and disease-free, whereas 50% of those with appendectomy alone died 4

Critical Staging and Workup

Preoperative/Intraoperative Assessment

• Perform thorough abdominal exploration during surgery, examining the entire peritoneal cavity, liver, and pelvis, as adenocarcinoma of the appendix frequently presents with advanced disease (60% present with Duke's C or D) 4
• Complete colonoscopy is essential to rule out synchronous colorectal malignancies, as 35% of patients develop second primary malignancies (17 in the gastrointestinal tract) 1

Postoperative Staging for Incomplete Resection

• For patients with incomplete resection or tumors ≥2 cm after initial appendectomy, obtain abdominal/pelvic CT or MRI to rule out distant disease 2
• If no distant disease is identified, proceed with secondary right hemicolectomy 2

Special Considerations

Adenocarcinoid (Goblet Cell Carcinoid) Variant

• These tumors should be managed according to colon cancer protocols rather than typical carcinoid protocols, as they behave more aggressively 5, 6
• Right hemicolectomy is the standard surgical approach for these variants 5

Adjuvant Therapy

• Postoperative radiation therapy appears to provide benefit for both local control and overall survival in locally advanced disease 7
• Adjuvant chemotherapy should be considered for patients with lymph node involvement 8

Prognostic Factors

Stage-Specific Survival

• 5-year survival varies significantly by stage: Stage A (100%), Stage B (67%), Stage C (50%), Stage D (6%) 1
• Tumor grade also impacts survival: Grade I (68%), Grade III (7%) 1
• Mucinous type has better prognosis than colonic type 1

Common Pitfalls to Avoid

• Do not rely on simple appendectomy for tumors >1 cm or those with any high-risk features, as this results in significantly worse outcomes 1, 4
• Do not assume the diagnosis preoperatively is correct—in most series, the correct diagnosis was not made before surgery and was entertained intraoperatively in only 32% of cases 1
• Do not neglect surveillance for second primary malignancies, particularly in the gastrointestinal tract, as these occur in 35% of patients 1
• Ensure at least 12 lymph nodes are analyzed to adequately stage the disease 5