Ten-year recurrence-free survival in stage IV perforated appendiceal mucinous adenocarcinoma with high-risk features:...

Appendiceal mucinous adenocarcinoma (MAC) associated with pseudomyxoma peritonei (PMP) has a poor prognosis in advanced stages. Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is generally regarded as the standard treatment for PMP, but its management may require individualization based on tumor burden, histopathological risk, the patient's condition, and available treatment options.

A 71-year-old man was initially managed conservatively for suspected acute appendicitis and was later referred to our department because of persistent appendiceal enlargement. Before the planned outpatient evaluation, he developed perforated appendicitis and underwent emergency laparoscopic appendectomy. Pathological examination showed MAC with high-risk features and a positive surgical margin. After multidisciplinary discussion, additional surgery aimed at macroscopic disease reduction was performed without CRS/HIPEC, including right hemicolectomy, lymph node dissection, and resection of visible peritoneal nodules and a paracaval lymph node. Postoperative FDG-PET/CT suggested residual pelvic disease, and systemic chemotherapy with capecitabine, oxaliplatin, and bevacizumab was administered. A clinical complete response was achieved, and the patient has remained recurrence-free for 10 years.

This case suggests that long-term recurrence-free survival may be possible when the biologically active tumor burden is limited, timely surgery achieves substantial macroscopic disease reduction, and effective systemic chemotherapy controls residual disease, even if CRS/HIPEC is not performed.

Long-term RFS may be achievable in carefully selected patients with stage IV appendiceal MAC and PMP, even without CRS/HIPEC. This case does not challenge CRS/HIPEC as the standard strategy for PMP but supports individualized multidisciplinary decision-making when CRS/HIPEC is not feasible or not selected.