Bone is the most frequent metastasis site of the patients with breast cancer. We investigated to identify prognostic factors affecting survival following bone-only metastasis for breast cancer patients.
Patients and method
The medical records of breast cancer patients, who were treated and followed at Gangnam Severance Hospital, Yonsei University, Seoul, Korea, were retrospectively reviewed to identify patients with bone metastasis. Among them, patients who developed bone metastasis during follow up periods and patients with bone-only metastasis at the initial diagnosis were included in this study.
91 patients (82.7%) had bone-only recurrence and 19 (17.3%) showed bone metastasis at the initial diagnosis (De Novo bone metastasis). The Kaplan-Meier overall survival estimate at 5 year for the breast cancer patients with De Novo bone metastasis was higher than that for the patients with bone-only recurrence (60.2 vs. 44.1 %); however, there was no statistically significant difference between their overall survival estimates (log-rank test, P = 0.136). In the multivariate Cox regression model selected by Akaike Information Criteria, bisphosphonate treatment (hazard ratio (HR) 0.18, 95% CI 0.07 - 0.43), presence of estrogen receptor (HR 0.51, 95% CI 0.28 – 0.94), and solitary bone metastasis (HR 0.32, 95% CI 0.14 – 0.72) were the significant prognostic factors associated with longer overall survival in the bone-only recurrence group.
Our finding of the identification of the prognostic factors having an effect on breast cancer mortality after bone-only metastasis will help to understand the clinical course and improve the treatment outcome of bone-only metastasis from breast cancer. Bisphosphonate treatment identified as one of the most significant prognostic factors in our study warrants further investigation