Clinical Application And Precision Medicine: The Diagnostic Revolution From Tissue Sampling To Molecular Subtyping

Breast biopsy needles play an indispensable role in precision medicine for breast cancer. The tissue samples they procure serve not only as the foundation for pathological diagnosis, but also as critical material for molecular subtyping, targeted therapy selection, and prognostic evaluation. With the rapid advancement of molecular pathological diagnostics, technical requirements for biopsy needles have evolved from "obtaining sufficient tissue" to "acquiring high‑quality, intact samples suitable for multi‑omics analysis".

Technological Evolution of Molecular Pathological Diagnosis

Traditional breast cancer diagnosis relies on histomorphological observation and limited immunohistochemical markers (e.g., ER, PR, HER2). The established classification into Luminal A/B, HER2‑enriched, and triple‑negative subtypes has greatly advanced endocrine therapy and anti‑HER2 targeted treatment, yet it cannot fully explain the substantial inter‑patient heterogeneity in prognosis and therapeutic response. Driven by rapid progress in molecular pathology, especially the widespread adoption of next‑generation sequencing (NGS), breast cancer diagnosis has transitioned from conventional morphological and IHC‑based subtyping into an era of precision classification grounded in genomic, transcriptomic, and proteomic profiling.

Genetic Testing as a Mandatory Component of Treatment

The 2025 updates to the CSCO and NCCN Breast Cancer Guidelines further underscore the central role of genetic testing in breast cancer management. Genetic testing has shifted from an optional procedure to a mandatory requirement, ushering in a new era of refined molecular subtyping. The 2025 CSCO Guidelines added the PIK3CA gene as a testing target and elevated the recommendation level for BRCA1/2 mutation‑associated therapeutic regimens. In the section on breast cancer diagnosis and examination, the guidelines recommend routine PIK3CA testing prior to first‑line therapy for patients with hormone receptor‑positive, HER2‑negative locally advanced or metastatic breast cancer, with NGS or PCR as recommended detection methods.

Quality Requirements for Biopsy Specimens

Modern molecular pathology imposes stricter standards on biopsy samples. Although fine‑needle aspiration (FNA) is minimally invasive with a complication rate below 1%, it yields limited cellular material insufficient for multi‑gene panel testing. Vacuum‑assisted biopsy (VAB) retrieves larger, more intact tissue specimens with a single sample mass exceeding 20 mg and a cellular degeneration rate below 5%, making it ideal for comprehensive molecular profiling. Studies indicate that percutaneous breast biopsy combined with IHC achieves a diagnostic accuracy of up to 95%, and international guidelines recognize it as the gold standard for definitive breast cancer diagnosis.

Updates to Clinical Practice Guidelines

The Clinical Practice Guidelines for Molecular Pathological Testing of Breast Cancer (2025 Edition) strongly recommend PD‑L1 testing for patients with triple‑negative breast cancer to guide treatment selection. For advanced breast cancer patients with negative conventional molecular markers and progressive disease despite standard therapy, pan‑solid‑tumor molecular profiling is recommended where feasible to identify potential targeted therapy opportunities, including NTRK/RET fusions, MSI‑H/dMMR, and TMB‑H. Large‑panel NGS is recommended for simultaneous detection to improve testing efficiency.

Technology Platform Selection and Specimen Optimization

The guidelines prioritize NGS for advanced breast cancer, as it enables simultaneous multi‑gene analysis, accommodates diverse sample types such as tissue and liquid biopsies, and minimizes tissue consumption. Nevertheless, NGS has technical limitations in detecting gene fusions; FISH or RT‑PCR may be required for confirmatory testing. This imposes new design demands on biopsy needles: they must procure sufficient high‑quality tissue while minimizing trauma and cellular degeneration to guarantee accurate molecular testing.

Future Development Directions

With advances in liquid biopsy, circulating tumor DNA (ctDNA) analysis has emerged as a new modality for breast cancer surveillance. Even so, tissue biopsy remains the diagnostic gold standard, particularly for evaluating neoadjuvant therapy response and investigating resistance mechanisms. Future biopsy needles will become increasingly intelligent, integrating real‑time molecular analysis to deliver preliminary on‑site molecular data and support immediate clinical decision‑making. Meanwhile, the integration of minimally invasive biopsy with image guidance and artificial intelligence will further enhance procedural precision and safety, propelling breast cancer care toward greater personalization and precision.