ASCO 2019: What Impact on my Breast Cancer Clinical Practice?

The importance of characterizing breast cancers.

The new AJCC staging procedure for non-metastatic breast cancers reflects:

• The importance of clinical and pathological staging.

• The predictive and prognostic value of ER and HER2 positivity.

• The prognostic impact of molecular signatures.

Important questions:

• What is the appropriate definition of ER positive breast cancer?

• What is the appropriate definition of HER2 positive breast cancer?

• Is Oncotype Dx® the only useful signature?

Based on the ASCO/CAP definition of ER positivity many questions are addressed:

• Do very low and low positive ER+ breast cancers share the same prognosis?

• Do very low and low positive ER+ benefit in the same ways from the adjuvant tamoxifen?

• Is the cut-off for positive of 10% used in some European countries more relevant regarding the adjuvant endocrine treatment effect?

• Can we do better with BCI?

What are the changes in new ASCO/CAP guidelines and how will they impact clinical practice?