Towards the treatment of invasive breast cancer

Threshold of oestrogen and progesterone for endocrine therapy

In women with invasive breast cancer, the ECIBC's Guidelines Development Group (GDG) suggests:

• administration of adjuvant endocrine therapy if 1% or greater of tumour cells show oestrogen receptor positivity rather than applying a threshold of 10% tumour cell oestrogen receptor positivity
  (conditional recommendation, very low certainty of the evidence)
• administration of adjuvant endocrine therapy if 1% or greater of tumour cells show progesterone receptor positivity rather than applying a threshold of 10% tumour cell progesterone receptor positivity (conditional recommendation, very low certainty of the evidence)

Multigene testing to guide the use of chemotherapy

To guide the use of chemotherapy in women with hormone receptor positive, HER2-negative, and lymph node negative or up to 3 lymph nodes positive invasive breast cancer, the ECIBC's Guidelines Development Group (GDG):

• recommends not using the 70 gene signature test when women are at low clinical risk (strong recommendation, low certainty of the evidence)
• suggests using the 70 gene signature test when women are at high clinical risk (conditional recommendation, low certainty of the evidence)
• suggests using the 21 gene recurrence score (conditional recommendation, very low certainty of the evidence)