Should mucosal bowel invasion in ovarian cancer be assigned to FIGO stage IV disease?

Objectives: The FIGO staging consensus agreement from 2012 indicates that bowel mucosal invasion for epithelial ovarian cancer (EOC) should be assigned to stage IV disease. Finding no evidence justifying this recommendation, we examined the impact of recto-sigmoid colonic invasion on survival based on depth of invasion. Methods: Patients having recto-sigmoid resection to achieve complete gross resection for stage IIIC/IV EOC between 2003 and 2011 were included. For this study, mucosal invasion alone was not considered as stage IV. Degree of bowel invasion was defined as: serosal/subserosal vs. muscularis/submucosa/mucosa. Patients with only mesenteric invasion were excluded. Intraperitoneal disease (IP) dissemination patterns were defined as pelvic, lower abdomen, upper abdomen, and miliary disease. Comparisons between groups were evaluated using the log-rank test for progression-free and overall survival (PFS, OS) and the chi-square test for IP dissemination pattern. Results: Eighty-five patients were included with a mean age of 64.5 years. Most cases were serous (87.1%) and stage IIIC (83.5%). There were 53 (62.4%) patients with serosal/subserosal and 32 (37.6%) with muscularis/submucosa/mucosa invasion. Although not statistically significant, PFS and OS both favored cases with deeper invasion (muscularis/submucosa/mucosa vs. serosal/subserosal invasion: median PFS, 33.5 vs. 18.2 months, p = 0.34; median OS, 82.3 vs. 51.5 months, p = 0.46). When comparing patterns of disease dissemination, we observed that patients with serosal/subserosal invasion (vs. those with deeper invasion) tended to have more upper abdominal or miliary disease (67.9% vs. 48.4%, p = 0.08). Conclusions: Depth of recto-sigmoid colon wall invasion does not have prognostic significance. Our observations do not support assignment to a higher FIGO stage (IV) based solely on this factor.