Solitary Bone Metastasis and Oligometastatic Bone Disease in Breast Cancer: Are They Two Different Entities?

Abstract In this study, we planned to investigate the clinical course of breast cancer patients with oligometastatic bone disease (OMBD).The patients were grouped according to the characteristics and the sites of metastases. Group I included 928 patients without metastasis. Group II, OMBD group, icluded 68 patients. Group III, widespread metastasis group, consisted of 185 patients with multiple bone metastases and/or solid organ metastases.The mean overall survival of the groups were 16.7 ± 0.3 years in Group 1, and 7.8 ± 0.8 and 5.9 ± 0.4 years in Group 2 and 3, respectively (p<0,001 for the comparison of all three groups together; p <0.001 for Group 1 vs 2 & 3) and (p=0.037 for Group 2 vs. Group 3). In the subgroup survival analysis of patients in Group 2 (OMBD), the mean and median survival were 5.5 ± 0.8 and 4.0±0.8 years versus 9.2 ± 0.98 and 9.0 ±1.05 years in more than one bone metastasis and SBM patients, respectively (p = 0.019).As a result; OMBD seems to be a different disease than breast cancer with isolated bone metastases. The high risk of developing OMBD especially following locoregional recurrences increases the importance of locoregional therapy in large T and N stage tumors.