Lessons on responsiveness to adjuvant systemic therapies learned from the neoadjuvant setting

Area of Science:

• Oncology
• Molecular Biology
• Clinical Therapeutics

Background:

• Operable breast cancer treatment relies on understanding diverse tumor subtypes.
• Identifying predictive factors and targets is crucial for effective therapy selection.
• Recent advancements focus on predictive factors in the neoadjuvant setting.

Purpose of the Study:

• To review established predictive factors for response in neoadjuvant breast cancer treatment.
• To highlight the role of molecular and immunohistochemical markers in guiding therapy.
• To inform clinical trial design and patient selection for preoperative therapies.

Main Methods:

• Review of experimental and clinical studies on predictive factors in breast cancer.
• Analysis of estrogen receptor (ER) and progesterone receptor (PgR) expression levels.
• Evaluation of HER2 overexpression/amplification as a predictive marker.
• Assessment of cell proliferation markers (Ki-67, grade) and histotype (lobular vs. ductal).

Main Results:

• ER/PgR expression defines distinct biological entities impacting neoadjuvant treatment response.
• Tumors with high ER/PgR benefit little from chemotherapy; absence correlates with pathologic complete remission (pCR).
• Invasive lobular carcinoma shows lower pCR rates than ductal carcinoma.
• High cell proliferation (Ki-67, high grade) predicts chemotherapy response.
• HER2 positivity correlates with higher pCR rates in patients receiving neoadjuvant chemotherapy.

Conclusions:

• Predictive factors enable more effective application of neoadjuvant therapies.
• Identifying patients likely to benefit substantially from treatment is achievable.
• Tailoring therapy based on predictive markers optimizes outcomes in operable breast cancer.