Refining the classification of breast phyllodes tumours.

Area of Science:

• Oncology
• Pathology
• Breast Cancer Research

Background:

• Phyllodes tumours of the breast are rare fibroepithelial neoplasms.
• Current classification relies on multiple histological parameters, leading to grading challenges.
• Pathologist concordance in typing and grading is often low, particularly for borderline cases.

Purpose of the Study:

• To address the recurrent classification challenges in phyllodes tumours of the breast.
• To explore the translation of molecular findings into clinical practice for phyllodes tumours.
• To outline a multipronged approach for refining phyllodes tumour classification.

Main Methods:

• Review of histological parameters used for grading phyllodes tumours.
• Assessment of the application of World Health Organization (WHO) Classification criteria in routine practice.
• Consideration of recent molecular information and its diagnostic utility.
• Leveraging global contributions from the International Fibroepithelial Consortium.
• Utilizing support from the International Collaboration on Cancer Classification and Research (IC³R) and International Collaboration on Cancer Reporting (ICCR).

Main Results:

• Histological parameters like stromal hypercellularity, atypia, mitotic count, overgrowth, and tumour borders contribute to classification difficulties.
• Discrepancies exist in the routine application of WHO diagnostic criteria.
• Molecular data has shown diagnostic promise but is not yet integrated into daily practice.
• A collaborative, evidence-based strategy is proposed to enhance classification reproducibility and prognostic precision.

Conclusions:

• Refining the classification of phyllodes tumours is essential for improved patient outcomes.
• A standardized, reproducible, and prognostically precise classification system is needed.
• International collaboration and evidence translation are key to advancing phyllodes tumour classification.