Prognostic factors in patients with metastatic breast cancer at the time of diagnosis.

Approximately 90% of breast cancer mortality is due to metastases that are resistant to adjuvant therapies. Thus, assessment of factors associated with clinical outcomes in patients with advanced breast cancer is of significant importance. Despite the recent improvement in early detection, between 5 and 10% of breast cancer patients are diagnosed with metastasis at initial presentation or, rarely, before the primary breast cancer has been identified. These patients typically have poorer survival outcomes compared to those who develop distant metastasis subsequently. Yet, the prognostic relevance in these patients has not been intensively explored. In this study, we analyzed breast cancer patients with distant metastasis at the time of diagnosis between 1997 and 2010 (n=194) to identify the clinicopathological factors significant for overall survival. By univariate analysis, race, estrogen receptor (ER) and progesterone receptor status were significantly associated with overall survival, while race and ER remained independent factors in multivariate analysis. Being Caucasian and overexpressing of ER both showed a significantly decreased hazard of death (P=0.015 and 0.017, respectively). Reflecting these findings, the overall survival differed significantly between breast subtypes, with the luminal subtype and triple negative disease being associated with the longest and worst survival, respectively. Further, multi-organ involvement was associated with a worse prognosis than those with single organ metastasis, whereas no significant difference in survival was found between the different anatomic sites (bone, viscera and brain). Our findings suggest that it is predominantly the intrinsic nature of the tumor along with the genetic makeup of the patient that predicts the prognostic outcome in those patients with advanced disease at presentation.