Appendectomy followed by two-stage right-sided colectomy with lymph node dissection for appendiceal cancer and risk factors for peritoneal recurrence: a single high-volume cancer center study in Japan.

Purpose: Few studies have evaluated whether the timing of colectomy affects the prognosis of appendiceal cancer. This study compared long-term outcomes and recurrence patterns between initial appendectomy followed by two-stage colectomy and one-stage colectomy for appendiceal cancer.

Methods: We retrospectively evaluated 65 patients who underwent 2-stage (n = 17) or 1-stage (n = 48) right-sided colectomy with lymph node dissection for stage 0-III appendiceal cancer between August 2005 and December 2022. The recurrence types and risk factors were compared.

Results: The 2-stage colectomy group had a more advanced disease stage than the 1-stage group (stage III cases: 29.4% vs. 14.6%, P = 0.03). The 5-year overall recurrence rates were similar between the groups (29.4% vs. 19.2%, P = 0.39). All peritoneal recurrence cases (n = 9) had pT3 or T4 depth. Among pT3 and T4 cases (n = 46), the peritoneal recurrence rates did not differ significantly (31.2% vs. 13.8%, P = 0.17). A multivariate analysis identified preoperative serum CA19-9 level of > 37 ng/mL (hazard ratio [HR], 35.4; 95% confidence interval [CI], 3.08-406.8; P = 0.004) and lymph node metastasis (HR, 42.6; 95% CI, 9.90-183.6; P < 0.001) as independent risk factors for peritoneal recurrence.

Conclusions: Serum CA19-9 levels and lymph node metastasis are risk factors for peritoneal recurrence. The effect of colectomy timing on recurrence was not definitive.