12. Towards the treatment of invasive breast cancer
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)
Threshold of oestrogen for endocrine therapy
Issued on: September 2017
Healthcare question
Should a threshold of 10% or more vs. 1% or more of cells showing oestrogen receptor positivity be used for providing endocrine therapy in women with invasive breast cancer?
Recommendation
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.
Recommendation strength
| Conditional recommendation |
| Very low certainty of the evidence |
Justification
The GDG agreed by consensus that the limited very low quality evidence reviewed favours the current practice, using an oestrogen receptor (ER) threshold of 1% positivity.
Monitoring and evaluation
The GDG suggested monitoring low (1-9%) and high (10% and above) ER positivity in relation to patient outcomes to better assess ER thresholds for treatment.
Research priorities
- New research using ideally modern oestrogen receptor (ER) immunohistochemical techniques on tumour tissue primarily fixed in 10% neutral buffered formalin.
- The GDG suggested additional observational studies to provide evidence on the current threshold used in practice, ideally using modern immunohistochemical techniques.
Supporting material