Laparoscopic cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for perforated low-grade appendiceal mucinous neoplasms.

Introduction: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is an established treatment for pseudomyxoma peritonei (PMP) from perforated low-grade appendiceal mucinous neoplasms (LAMN II). In a selected group of LAMN II patients without established PMP, CRS/HIPEC can be performed laparoscopically (L-CRS/HIPEC); however the short-term benefits and safety of this approach have yet to be determined. This study aims to determine the short-term outcomes from a series of L-CRS/HIPEC LAMN II patients compared to those who have undergone a similar open operation (O-CRS/HIPEC) for low-volume PMP.

Methods: LAMN II patients undergoing L-CRS/HIPEC at a UK national peritoneal tumour centre were compared to O-CRS/HIPEC patients (peritoneal cancer index ≤ 7). Outcomes of interest included Clavien-Dindo complication grade, operative time, blood transfusions, high dependency unit (HDU) admission, length of hospital stay, and histopathological findings.

Results: 55 L-CRS/HIPEC were compared to 29 O-CRS/HIPEC patients (2003-2017). Groups were matched for age, sex, and procedures. Median operative time was 8.8 (IQR 8.1-9.5) h for L-CRS/HIPEC versus 7.3 (IQR 6.7-8) h for O-CRS/HIPEC (Mann-Whitney test p < 0.001). Post-operative HDU admission was 56% versus 97% (OR 0.04 95% CI 0.01-0.34) and median length of stay = 6 (IQR 5-8) versus 10 (IQR 8-11) days (p < 0.001) for L- versus O-CRS/HIPEC. Despite a normal pre-operative CT scan, 13/55 (23.6%) L-CRS/HIPEC patients had acellular mucin and 2/55 (3.5%) had mucin with epithelium present in their specimens. Residual appendix tumour was identified in 2/55 patients (3.6%). Clavien-Dindo Grade 1-4 complications were similar in both groups with no mortality.

Conclusion: L-CRS/HIPEC for LAMN II takes longer; however patients have significantly reduced length of HDU and overall stay, without increased post-operative complications. A significant proportion of LAMN II patients undergoing L-CRS/HIPEC have extra-appendiceal acellular mucin with some cases demonstrating residual cellular epithelium from the LAMN II. The risk of these patients developing PMP without surgery is under current review.