EP141/#791 Does positive peritoneal cytology alter oncologic outcomes of patients with clinical early stage low-grade endometrioid endometrial carcinoma?

Objectives

Investigate the prevalence and outcomes of positive peritoneal cytology among patients with clinical early stage low-grade endometrioid endometrial carcinoma (EEC).

Methods

Patients with no history of another tumor diagnosed between 2010–2015 with clinical early-stage grade 1 or 2 EEC after hysterectomy with lymphadenectomy and known peritoneal cytology, as well as data on depth of myometrial invasion, lymph node and lymph-vascular invasion (LVSI) status were included. Overall survival (OS) was compared with log-rank test following generation of Kaplan-Meier curves. Cox model was constructed to control for confounders.

Results

33161 patients met inclusion criteria; 1553 (4.7%) had positive peritoneal cytology. Patients with positive peritoneal cytology were younger (median 61 vs 62 years, p<0.001), more likely to have grade 2 tumors (52.2% vs 42.1%, p<0.001), outer half myometrial invasion (38.4% vs 23.3%, p<0.001), positive lymph nodes (14.6% vs 3.9%) and LVSI (28.7% vs 11.9%, p<0.001). They were more likely to receive radiation therapy (36.4% vs 19.4%,p<0.001), and chemotherapy (22.6% vs 4%, p<0.001). There was no difference in OS between patients with negative and positive peritoneal cytology (p=0.10; 4-year OS rates were 94.5% vs 93.2% respectively). Positive peritoneal cytology was not associated with worse OS when controlling for confounders (HR: 1.06, 95% CI: 0.86, 1.30) neither when excluding lymph node metastases (HR 1.23, 95% CI: 0.99, 1.53). Negative lymph nodes and positive peritoneal cytology (n=1322), radiation therapy (p=0.59) and chemotherapy (p=0.83) were not associated with better OS.

Conclusions

For patients with clinical early-stage low-grade EEC, positive peritoneal cytology was rare and not associated with worse overall survival.