Clinicopathological and genomic features of breast mucinous carcinoma

INTRODUCTION: Mucinous carcinoma (MC) of the breast is a special histological type of breast cancer. Clinicopathological characteristics and genomic features of MC is not fully understood. MATERIALS AND METHODS: 186,497 primary breast cancer patients from SEER database diagnosed with invasive ductal carcinoma (IDC) or MC were included. 801 primary IDC or MC patients from TCGA cohort were included for transcriptomic and genomic analysis. RESULTS: MC patients were older, had lower tumor grade and T and N stage, higher hormone receptor positive proportions and lower HER2 positive proportions than IDC patients. Kaplan-Meier plots showed that the breast cancer-specific survival (BCSS) of MC patients was significantly better than IDC patients (P < 0.001). However, after adjusting for clinicopathological factors, survival advantage of MC disappeared. In terms of genomic features of MC, representative upregulated genes of MC in transcriptomic level were MUC2, TFF1 and CARTPT. Upregulated pathways of MC included neurotransmitter-related pathways. Moreover, MC was featured by the amplification of 6p25.2, 6q12 and 11q12.3. CONCLUSION: MC is a distinct histological subtype compared with IDC in terms of clinicopathological characteristics and genomic features. Further investigation need to be conducted to explore the formation of this specific histological subtype.