Advanced Pseudomyxoma Peritonei Requiring Gastrectomy to Achieve Complete Cytoreduction Results in Good Long-Term Oncologic Outcomes.

BACKGROUND: Optimal outcomes in pseudomyxoma peritonei (PMP) require complete macroscopic tumor removal by cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). Partial or complete gastrectomy may be required with ongoing debate as to the risks and benefits of gastrectomy in what is often a low-grade malignancy.

METHODS: Retrospective single-center analysis of 1014 patients undergoing CRS and HIPEC for PMP of appendiceal origin. Complications and survival were compared in patients who had gastrectomy versus the nongastrectomy cohort.

RESULTS: Of 1014 patients, 747 (74 %) had CRS and HIPEC with complete cytoreduction. Overall, 86 (12 %) of 747 had partial (n = 80) or total (n = 6) gastrectomy. Median age was 55 years for gastrectomy patients and 56 for nongastrectomy patients (p = 0.591). Preoperative tumor markers [carcinoembryonic antigen, carbohydrate antigen (CA) 125 and CA19-9] were elevated more frequently in the gastrectomy group compared to the nongastrectomy group [81, 61 and 81 % compared to 41 % (p = 0.001), 20 % (p = 0.001) and 39 % (p = 0.001), respectively]. The proportion of high-grade histology was similar in the two groups (gastrectomy 19 % vs. nongastrectomy 18 %, p = 0.882). Postoperative complications (Clavien-Dindo III-IV) were 31 % for the gastrectomy group and 13 % for the nongastrectomy group (p = 0.001). The 30-day postoperative mortality was 3 (0.5 %) of 661 for the nongastrectomy group and 1 (1.2 %) of 86 for the gastrectomy group (p = 0.387). Three- and 5-year overall survival were 96 and 88 % in the nongastrectomy group and 87 and 77 % in the gastrectomy group (p = 0.018). Three- and 5-year disease-free survival were 89 and 77 % in the nongastrectomy group versus 66 and 48 % in the gastrectomy group (p = 0.001).

CONCLUSIONS: Gastrectomy is an essential component of complete cytoreduction in advanced PMP and was required in 12 % of patients with good long-term survival.