Extracellular vesicles in nipple discharge for breast cancer screening.

PURPOSE: Nipple discharge (ND) is one of its major symptoms of breast cancer. However, the low volume of NDs has limited their diagnostic capability. This study aimed to identify extracellular vesicles (EVs) miRNAs in ND using cellulose nanofiber (CNF) sheets to develop clinical biomarkers.

METHODS

Patients with ND from two independent institutions between 2023 and 2024 were included. ND-EVs were isolated from 23 samples [normal, n = 8; intraductal papilloma, n = 1; ductal carcinoma in situ (DCIS), n = 8; invasive ductal carcinoma, n = 6] using CNF sheets. Additionally, miRNAs were also analyzed from intracystic fluid, tumor tissue, and tissue surface EVs from the same patients, and miRNA sequencing was performed.

RESULTS

miRNA sequencing for ND-EVs revealed distinct clustering between cancer and normal groups, identifying miR-342-3p, miR-20b-5p, and miR-550a-5p as candidate biomarkers. ND-EV miRNA profiles reflected tumor tissue characteristics, especially in DCIS. Four additional miRNAs (miR-92b-3p, miR-375-3p, miR-182-5p, miR-96-5p) were commonly upregulated in DCIS tissue, tissue surface, and ND-EVs. These miRNAs were validated by qRT-PCR. ROC curve analyses demonstrated that combining the five miRNAs yielded high diagnostic performance, with AUCs of 0.902 for breast cancer and 0.938 for DCIS. A subset of three miRNAs also showed robust discrimination ability.

CONCLUSION

ND-EV miRNAs collected via CNF sheets show great potential as noninvasive biomarkers for early breast cancer detection.