Clinicopathological and Prognostic Implications of Circulating MicroRNA-429 in Breast Cancer Patients.

BACKGROUND/

Aims

MicroRNA-429 (miR-429), a member of the miR-200 family, has been implicated in epithelial-mesenchymal transition and tumor progression, yet its clinicopathological significance in breast cancer remains unclear. This study aimed to evaluate serum miR-429 expression in treatment-naïve breast cancer patients and correlate its levels with detailed histopathological variables, molecular subtype, treatment response, and outcome.

Materials And Methods

In this prospective study, serum samples from 49 invasive ductal carcinoma (IDC- no special type [NST]) patients and 49 age-matched healthy controls were analyzed by quantitative real-time polymerase chain reaction. Clinicopathological data (tumor grade, receptor status, lymphovascular invasion [LVI], nodal status, mitosis, tumor-infiltrating lymphocytes, necrosis, and subtype) and treatment response (Response Evaluation Criteria in Solid Tumors [RECIST] v1.1) were recorded. Resection specimens were evaluated for residual cancer burden (RCB).

Results

Mean serum miR-429 levels were significantly lower in cases than controls (0.92 ± 0.53 vs. 1.24 ± 0.55; t = 2.892, P = 0.005). Receiver operating characteristic analysis showed an area under the curve of 0.649 (95% confidence interval: 0.540-0.758; P = 0.011) with 67.3% sensitivity and specificity at a cut-off of <1.005. Higher miR-429 expression was significantly associated with LVI (37.5% vs. 0%, P = 0.021). Trends toward higher mitotic activity (≥6 mitoses/10 hpf: 62.5% vs. 25.0%, P = 0.094) and greater nodal involvement (50.0% vs. 20.0%, P = 0.096) were noted in the high-expression group. No significant associations were observed with grade (P = 0.190), receptor status (estrogen receptor P = 0.354; progesterone receptor P = 0.614; HER2 P = 0.579), molecular subtype (P = 0.852), RCB (P = 0.418), or RECIST response (P = 0.627). At follow-up, 42 patients (85.7%) were doing well, 5 (10.2%) had died, and outcomes were not significantly related to miR-429 (P = 0.351).

Conclusion

Serum miR-429 is downregulated in breast cancer and correlates significantly with LVI, suggesting a role in invasive biology. While diagnostic utility is modest, its integration into multi-microRNA panels may enhance predictive accuracy. Larger, multi-institutional, subtype-stratified studies are needed for validation.