Breast MR imaging changes after neoadjuvant chemotherapy: correlation with molecular subtypes.

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Neoadjuvant chemotherapy is a standard treatment for locally advanced breast cancer.
• Magnetic Resonance Imaging (MRI) is crucial for assessing treatment efficacy.
• Understanding treatment response across molecular subtypes is essential for personalized medicine.

Purpose of the Study:

• To quantify neoadjuvant chemotherapy response in different breast cancer molecular subtypes using MRI.
• To describe morphological and dynamic changes observed on MRI post-treatment.
• To investigate potential shifts in molecular phenotype after chemotherapy.

Main Methods:

• Retrospective analysis of 75 breast cancer cases (69 patients) with pre- and post-neoadjuvant chemotherapy MRI.
• Classification of treatment response: complete, major partial, minor partial, or no response.
• Quantification of response by molecular subtype (Luminal A, Luminal B, Her2+, triple negative) and analysis of morphological/dynamic MRI features.

Main Results:

• All four molecular subtypes exhibited varying degrees of response to neoadjuvant chemotherapy.
• Triple-negative subtype showed the highest response rate (84.6%), followed by Luminal B (76.9%), Luminal A (75.6%), and Her2+ (69.2%).
• Predominant morphological change was concentric reduction (75%); main dynamic change was decreased maximum intensity peak (64.2%).

Conclusions:

• Triple-negative breast cancer demonstrates superior response to neoadjuvant chemotherapy.
• MRI reveals common post-treatment changes including concentric reduction and diminished intensity peaks.
• A small percentage (12.2%) of cases showed a molecular phenotype change from diagnosis to post-treatment.