MCP‐1 expression in breast cancer and its association with distant relapse

BACKGROUND: Distant relapse of breast cancer complicates management of the disease and accounts for 90% of breast cancer‐related deaths. Monocyte chemoattractant protein‐1 (MCP‐1) has critical roles in breast cancer progression and is widely accepted as a pro‐metastatic chemokine. METHODS: This study explored MCP‐1 expression in the primary tumour of 251 breast cancer patients. A simplified ‘histoscore’ was used to determine if each tumour had high or low expression of MCP‐1. Patient breast cancers were retrospectively staged based on available patient data. p < 0.05 was used to determine significance and changes in hazard ratios between models were considered. RESULTS: Low MCP‐1 expression in the primary tumour was associated with breast cancer‐related death with distant relapse in ER− breast cancers (p < 0.01); however, this was likely a result of most low MCP‐1‐expressing ER− breast cancers being Stage III or Stage IV, with high MCP‐1 expression in the primary tumour significantly correlated with Stage I breast cancers (p < 0.05). Expression of MCP‐1 in the primary ER− tumours varied across Stage I, II, III and IV and we highlighted a switch in MCP‐1 expression from high in Stage I ER− cancers to low in Stage IV ER− cancers. CONCLUSION: This study has emphasised a critical need for further investigation into MCP‐1's role in breast cancer progression and improved characterisation of MCP‐1 in breast cancers, particularly in light of the development of anti‐MCP‐1, anti‐metastatic therapies.