Real-life prognosis of 5041 bone-only metastatic breast cancer patients in the multicenter national observational ESME program

BACKGROUND: Bone-only (BO) metastatic breast cancer (MBC) is considered a more favorable entity than other MBC presentations. However, only few retrospective series and data from selected randomized controlled trials have been reported so far. METHODS: non-BO MBC at diagnosis, with adjustment on main prognostic factors using a propensity score. Secondary objectives were to compare first-line progression-free survival (PFS1), describe treatment patterns, and estimate factors associated with OS. RESULTS: < 0.0001]. Results were concordant in all analyses. CONCLUSION: BO MBC patients have better outcomes compared with non-BO MBC, consistently, through all MBC subtypes.