814P Clinical Significance of Isolated Pulmonary Recurrence in Patients with Endometrioid Endometrial Cancer Who Achieved Complete Remission after Primary Treatment

This study was to evaluate the clinical significance of pulmonary recurrence for patients who achieved complete remission after primary treatment of endometrioid endometrial cancer. This multicenter retrospective study included patients who had undergone primary treatment for endometrial cancer at six different hospitals between 2009 and 2019. Inclusion criteria were patients with endometrioid histology and no evidence of residual disease after primary treatment including standard surgical procedure. Patients who developed pulmonary metastasis during follow-up were identified. Time to second objective disease progression (PFS2) was defined as time from the start of second-line therapy to second recurrence, and second-line overall survival (OS2) was defined as time from the start of second-line therapy to death. Of the 1074 patients who met the inclusion criteria, 90 experienced recurrences. Pulmonary recurrence was the most frequent site of first recurrence, accounting for 34.4% (31/90) of all recurrences. Isolated pulmonary recurrence accounted for 64.5% (20/31) of all pulmonary recurrences, whereas 35.5% (11/31) of patients had concurrent recurrences at other sites. The median PFS2 and OS2 of patients with isolated pulmonary recurrence were significantly longer than those with concurrent recurrences at other sites (PFS2, 17.0 vs. 9.0 months, log-rank P = 0.004; OS2, not reached vs. 28.0 months, log-rank P = 0.001). During the median follow-up period of 88.0 months, 73.7% of patients with isolated pulmonary recurrence had recurrence or progression after second-line treatment, but only 15.8% of the patients died. On the other hand, during the median follow-up period of 33.0 months, 88.9% of patients with concurrent recurrence at other sites had recurrence or progression after second-line treatment and 66.7% died. Multivariable analysis identified isolated pulmonary recurrence as an independent factor for longer OS2 (HR, 0.18; 95% CI, 0.03-0.59; P = 0.009). Our study showed that isolated pulmonary recurrence is associated with prolonged OS2 in patients with recurrent endometrioid endometrial cancer.