Breast lesions of uncertain malignant potential represent a diagnostic challenge, as conventional histopathological assessment does not always reliably distinguish between benign and malignant changes.

The purpose of this prospective diagnostic study is to evaluate whether methylation patterns of selected breast cancer-related genes (BRCA1, RASSF1A, and PTEN) can help differentiate benign from malignant breast lesions.

Tissue samples obtained during diagnostic needle biopsy, and when applicable during surgical excision, will be analyzed for gene methylation status. The results will be compared with standard histopathological findings.

The study aims to improve diagnostic accuracy in breast lesions of uncertain malignant potential and contribute to better clinical decision-making in breast diagnostics.

Breast lesions of uncertain malignant potential (B3 category) pose a significant diagnostic challenge in clinical practice, as they carry a variable risk of malignancy and often lead to surgical excision despite a substantial proportion of benign outcomes.

Epigenetic alterations, particularly DNA methylation of tumor suppressor genes, are recognized as early events in breast carcinogenesis and may provide additional diagnostic information beyond conventional histopathology.

This prospective interventional diagnostic study investigates the diagnostic significance of methylation status of BRCA1, RASSF1A, and PTEN genes in breast lesions of uncertain malignant potential. Participants undergoing diagnostic evaluation for suspicious breast lesions will be enrolled after providing written informed consent.

Tissue samples obtained during diagnostic needle biopsy will be analyzed using molecular methods to determine gene methylation status. In cases where surgical excision is performed, methylation findings from needle biopsy specimens will be compared with those from surgical samples and correlated with final histopathological diagnosis.

The primary objective is to assess whether gene methylation patterns can distinguish benign from malignant breast lesions. Secondary objectives include evaluating concordance between needle biopsy and surgical specimens and analyzing differences in methylation profiles across histopathological lesion categories.

The study is conducted at the Institute of Oncology Ljubljana and does not influence clinical decision-making. All diagnostic and therapeutic procedures follow standard clinical practice.

Inclusion Criteria:

• Female patients aged 18 years or older.
• Patients referred for diagnostic evaluation of breast lesions of uncertain malignant potential.
• Availability of breast tissue samples obtained by diagnostic needle biopsy.
• Written informed consent for participation in the study.

Exclusion Criteria:

• Male patients.
• Patients younger than 18 years.
• Patients without breast lesions or without indication for diagnostic biopsy.
• Inadequate or insufficient tissue material for molecular analysis.
• Withdrawal of informed consent.