Tumor proximity to serosal surface as an independent prognostic factor in FIGO stage 1 endometrial cancer

Objective: Determine if tumor distance from serosal surface is an independent prognostic factor for disease recurrence and survival in stage 1 endometrial cancer. Methods: 747 patients diagnosed with stage 1 endometrial cancer between 1984 and 2015 were identified from an institutional database. This retrospective cohort was evaluated to assess differences in tumor distance from the serosal surface, histologic subtype, histologic grade, use of adjuvant treatment, recurrence rates and overall survival. Cox proportional hazard models were used to determine if variables of interest were related to recurrence and overall survival. Concordance correlation coefficients were used to compare our model to the 2009 International Federation of Gynecology and Obstetrics (FIGO) staging. Results: Tumor distance from serosal surface ranged from o mm-21 mm. 47 (8.7%) patients experienced recurrence. Patients with tumors located 5 mm or less from the serosal surface were 2.24 times more likely to experience recurrent disease (HR 2.24, 95% CI: 1.16 to 4.31, p = 0.02). Concordance rates for disease recurrence were 0.573 and 0.583 for our tumor distance model compared to the 2009 FIGO staging (95% CI: 0.568 to 0.579 and 95% CI: 0.577 to 0.589). Conclusions: Our study demonstrates that patients with tumors located 5 mm or less from the serosal surface have a two-fold increased risk of recurrence. Concordance rates are very similar between our model and the 2009 FIGO staging suggesting comparable predictability; these rates suggest there is room for improvement in both methods to predict disease recurrence and survival.