Bone Metastases as the Only Metastatic Site in Patients With Urothelial Carcinoma: Focus on a Special Patient Population

Worldwide, patients with urothelial carcinoma characterized by a bone-exclusive metastatic spread usually present with poor performance status, have limited access to active therapy, and have a poor outcome. Consequently, treatments offered and outcomes should be improved in this rare subgroup. Patients with exclusive bone metastatic spread from urothelial carcinoma (UC) throughout their disease course represent a rare subgroup with unique clinical features. These patients deserved special consideration in a retrospective multicenter study. Analyses were made from a pool of 1911 patients with a diagnosis of metastatic UC, from 23 centers. Baseline characteristics, access to treatment, and outcomes were analyzed according to metastatic spread. Univariable and multivariable Cox analyses were performed. A total of 128 evaluable patients (6.7%), diagnosed between February 1997 and April 2013, were identified. Eastern Cooperative Oncology Group performance status (PS) was ≥ 2 in 33.3% versus 17.7% of the remaining patients. Seventy-three (57%) received first-line chemotherapy, that was platinum-based in 50 patients (69%). Twenty-eight (21.9%) received second-line chemotherapy (vs. 75.9% and 32.2%, respectively, of the remaining patients). In multivariable analyses, no clinical factor was significantly associated with overall survival (OS). Among platinum chemotherapy-treated patients (total evaluable n = 972), significantly different relapse-free survival (RFS) and OS were observed according to bone metastases status (no bone metastases vs. bone metastases only vs. bone and other sites, P < .001). In these groups, 2-year RFS was 37.4%, 28.8%, and 25.9%, respectively. Two-year OS was 35.5%, 15.8%, and 23%, respectively. Patients with metastatic UC and bone-only metastases are less likely to receive systemic therapy than those with other metastases, likely because of their lower PS. The prognostic effect of having exclusive bone metastases or additional sites seems to be equally poor. These patients deserve new effective and tolerable agents, and improvements in the knowledge of their disease.