Cellularity in low-grade Pseudomyxoma peritonei impacts recurrence-free survival following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

PURPOSE

Documentation of cellularity in Pseudomyxoma peritonei (PMP) is not performed on a regular basis in everyday clinical practice, but is recommended by the PSOGI (Peritoneal Surface Oncology Group International). We investigated the impact of cellularity in PMP following cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) on recurrence-free survival.

METHODS

Data from 25 patients with low-grade (American Joint Committee on Cancer grade G1) PMP were retrospectively evaluated. Cellularity was categorized as acellular mucin, scant (< 2% cellularity), moderate (2-19% cellularity), or high cellularity (> 20% cellularity). Impact of cellularity, PCI, CC-score, and HIPEC regimen on recurrence-free and overall survival was primarily assessed.

RESULTS

Assessment of cellularity showed acellular mucin in ten patients (40%), scant cellularity in 11 (44%) patients, moderate cellularity in one (4%) patient, and high cellularity in three (12%) patients. Median PCI was 15 (range, 1-39). A CC-0 score was achieved in 13 (52%) patients and a CC-1 score was achieved in 12 (48%) patients. After a median follow-up of 25 (range, 2-74) months, all patients were still alive. Overall, four (16%) patients suffered from recurrent disease after a median of 38 (range, 36-60) months. PCI above 17 (p = 0.03) and moderate and high cellularity (p = 0.007) were statistically significantly associated with recurrent disease. CC-score and HIPEC compound used did not impact on recurrence-free survival.

CONCLUSIONS

Recurrent disease occurs more often in patients with PCI values above 17 and with moderate and high cellularity in low-grade PMP. Pathological assessment of cellularity is crucial for identification of patients at risk for recurrence.