Detection of bone metastases in uterine cancer: How common are they and should PET/CT be the standard for diagnosis?

OBJECTIVES: Osseous metastases (OM) in endometrial cancer (EMCA) are thought to be rare. This study aimed to address the gap in present knowledge by defining the rate of OM in endometrial cancer (EMCA) as stratified by histology and ascertaining the best diagnostic modality for detection. METHODS: 435 consecutive cases of EMCA evaluated in tertiary care setting were reviewed. Clinico-pathologic data were abstracted and analyzed. RESULTS: 18/403 patients were found to have OM (4.6%). Majority were detected by PET/CT (13/18 (72%)), with conventional CT scans missing the diagnoses otherwise made by PET/CT scans in 2/9 patients. Patients with type II EMCA were at higher risk of developing OM compared with patients with type I EMCA; 2/234 patients with type I EMCA (0.85%) developed OM, as compared to 16/167 patients with type II EMCA (9.58%), OR = 12.3. Patients with serous histology had significantly higher odds of developing OM when compared to patients with non-serous histologies (OR 4, p = 0.001, 95% CI 1.54 to 10.76). Kaplan Myer survival function and log-rank analysis showed that the presence of OM was a significant negative prognosticator of survival, with median overall survival (mOS) of 16 months in OM patients vs. mOS undefined in non-OM patients (p < 0.0001). DISCUSSION: Incidence of detected OM was clinically significant, with most cases identified by PET/CT scans. Patients with type II EMCA, and in particular serous histology, were at a significantly higher risk of developing OM. OM when present, is an indicator of aggressive cancer biology and poor prognosis. Further studies are needed to ascertain the mechanism of predisposition to OM formation in serous EMCA and to confirm PET/CT as modality of choice for detection of OM.