BMC Cancer 2009, 9:154 http://www.biomedcentral.com/1471-2407/9/154 P-value - - 0.003 - < 0.001 0.69 < 0.001 0.96 0.96 TFoigtualrpea1tients with metastatic bone disease Total patients with metastatic bone disease. (A) TTP_BD (P = 0.059), (B) OS (P < 0.001). It has been known that patients with hormone receptor (HR) positive tumors tend to develop more bone metas- tasis than those with HR negative tumors. As shown in Table 1, our study population reflected this trend. When we conducted the survival analysis of all patients, longer survival was associated with BP treatment as well as with HR positivity (Table 2). We therefore analyzed the effect of BP treatment on survival after stratifying HR status into HR positive and HR negative groups because we wanted to exclude the possible role of HR positivity as a confound- ing factor. bone and of SREs (except for the first event), these associ- ations were not statistically significant (Table 3). There was no significant difference in TTP_BD or OS associated with BP treatment (P = 0.117, P = 0.104 respectively) (Fig. 2). HER2 receptor positivity and visceral organ involvement were important factors in OS. These results were con- firmed through multivariate analysis. However, BP treat- ment was not a significant component for OS in HR positive patients (Table 4). The effect of BP treatment in the HR positive group Of the 230 patients whose tumors were HR positive, 202 patients (87.8%) received BP treatments. Although more patients in the BP group developed disease progression in The effect of BP treatment in the HR negative group Of the remaining 87 patients with bone metastasis whose tumors were HR negative, 60 (69%) patients were treated with BP for metastatic bone disease. There was no signifi- Table 2: Analysis for OS of total patients Univariate Multivariate Hazard ratio (95% CI) Hazard ratio (95% CI) Abbreviations: *, disease free interval; **, estrogen receptor; ***, progesteron receptor; †, bisphosphonate;. Page 4 of 9 (page number not for citation purposes) Variables Age <40 Post-menopausal state DFI* >2 yr Initial stage IV ER**/PR*** positive HER2 positive Visceral metastasis Sum of metastasis sites ≥ 3 BP† use 0.86 (0.66–1.13) 1.11 (0.77–1.59) 0.63 (0.48–0.83) 0.93 (0.67–1.29) 0.36 (0.27–0.48) 1.50 (1.13–1.98) 2.02 (1.55–2.65) 1.53 (1.17–2.00) 0.52 (0.37–0.73) P-value 0.29 0.59 0.001 0.66 < 0.001 0.005 < 0.001 0.002 < 0.001 - - 0.65 (0.48–0.86) - 0.41 (0.31–0.56) 0.94 (0.69–1.28) 1.93 (1.39–2.68) 0.99 (0.73–1.37) 0.70 (0.50–0.98)