The Impact of Sites of Metastases, Number and Time of Diagnosis on Clinical Outcomes for Breast Cancer Patients Receiving Palliative Chemotherapy

Abstract

Background and objective Approximately 10% of breast cancer patients are diagnosed at metastatic stage, whereas 30% develop metastases sometime after initial tumor diagnosis. Despite the availability of several therapeutic options for metastatic breast cancer (MBC), no predictive tools of response and/or survival are available to support clinical decision making. Our study aims to investigate the prognostic value of the timing of metastasis diagnosis and the site(s) and number of metastases in both response and survival.
Subject and methods Our prospective cohort study encompassed 235 metastatic breast cancer (MBC) patients receiving first-line chemotherapy. Response was evaluated for all patients after three cycles of treatment. Survival was assessed for 156 patients after a follow-up period of 18 months from the date of diagnosis of MBC. The relationships between the parameters and treatment outcomes (i.e., response and overall survival rate (OS) was studied using a chi-square and Kaplan-Meier tests, respectively. A Log Rank test was adopted for statistical comparisons between groups.

Results Higher percentage of patients initially diagnosed at metastatic stage did not experience disease progression (78.5%) compared with only 64.8% of patients diagnosed with metastases later (P=0.02). A better OS rate (87.7%) was observed among patients with initial metastases compared to OS of 70.3% in those who developed metastases later (P=0.009). Two thirds (77%) of the patients diagnosed with metastasis in a single site did not develop disease progression, compared to 63.9% of patients who were diagnosed with metastases in multiple sites (P=0.032). Single site metastases were also associated with a better survival tendency at an OS rate of 83.3% compared to 69.8% in those with multiple metastases (P=0.067). Our results revealed better survival rate in patients with bone metastases, with an OS rate reaching 90.1%, compared with patients with visceral metastases (70%), both bone and visceral metastases (78.6%), and both visceral and cerebral metastases (33.3%) (P=0.003). There was no clear effect of the sites of metastases to the response (P=0.126).

Conclusion Metastases diagnosed with primary breast cancer, single site of metastasis and bone metastases are predictors of better response and longer survival in breast cancer patients.