A clinicopathologic study of endometrial cancer metastatic to bone: Identification of microsatellite instability improves treatment strategies

Metastasis to bone (BM) is an uncommon manifestation of advanced endometrial cancer (EC). The present study will review the clinicopathologic features of a cohort of patients with EC and BM. We conducted a multi-center retrospective review of patients with EC and BM. Demographic and clinical information was extracted from the medical records. Survival outcomes were determined using Kaplan-Meier Curves. Final analysis included 10 patients. The median age was 65 years (range 31-71). 80% had FIGO stage III/IV disease. The most common site of BM was the spine (66%). All patients presented with extraosseous dissemination at the time of diagnosis of BM and 70% were found to have multiple sites of BM. 80% of patients were diagnosed with BM in the recurrent setting. The median time to diagnosis of bone recurrence was 14 months (range: 0-44). Median survival after diagnosis of BM was 11 months (range: 1-22 months). Patients with endometrioid histology and single site of bone metastasis experienced improved survival (p = 0.04 and p = 0.05, respectively). Eight patients had immunohistochemistry or molecular tumor profiles available for review. Seven of these patients (87.5%) were found to have microsatellite instability (MSI). The most common mutation was hypermethylation of MLH-1 (43%). To our knowledge, this is the first report demonstrating a correlation between MSI and metastasis to bone. The identification of BM in EC is uncommon, but will alter treatment strategies and dramatically impact prognosis. Molecular tumor profiling should be performed to identify targeted therapy options and optimize adjuvant treatment strategies.