Primary objective:

Determine the impact of the Oncotype DX Recurrence Score (RS) on the treatment recommendation made (administration of chemotherapy or not, in addition to hormonotherapy) in a HR+, N- or pN1(mi), Her2- breast cancer adjuvant population.

The impact of Oncotype DX on treatment recommendations can be either a decrease in treatment intensity defined as a change in treatment recommendation from chemotherapy plus hormonal therapy to hormonal therapy alone or an increase in treatment intensity defined as a movement from hormonal therapy alone to the addition of chemotherapy to hormonal therapy.

Patients with HR+, N- breast cancer currently represent around 70% of newly diagnosed breast cancers. These are usually good prognosis tumors. However, on the basis of classical clinical and pathological prognostic parameters and markers, the international consensus guidelines recommend treatment with hormone- and chemotherapy in 85-95% of the cases. Considering the natural disease history, such as documented by the EBCTCG meta-analysis, more than 50% of these patients are overtreated, which leads to unnecessary side effects and costs to the health system and to the society.

Oncotype DX appears to be well adapted to therapeutic de-escalation as it targets HR+, N- patients and is performed on fixed paraffin embedded tissue (FPET). It is therefore best adapted to daily clinical practice as it does not necessitate any specific surgical procedure or tissue freezing.

The prognostic and predictive value of Oncotype DX in ER+, N- patients has been validated on three large adjuvant randomized trials (NASBP B-14, NSABP B-20, and the ATAC study). The test has been commercially available in the USA since 2004, and is being used for more than 50% of the HR+ N- patients in this country.

While Oncotype DX has been validated in the USA, it needs to be independently evaluated in France, in the context of the local treatment guidelines and habits, to provide data that are meaningful to the French health system and to the French medical community.

Inclusion Criteria:

1. Patients > 18 years old.
2. Pre- or post- menopausal women with breast adenocarcinoma, confirmed by a pathologist and who underwent surgery, with a maximum of 4 weeks between surgery and the 2nd therapeutic decision with Oncotype DX.
3. HR positive (at least ER+) breast cancer patients (defined by a threshold of 10% of the cells IHC + without N- or pN1(mi), Her2 - (IHC0, 1, 2+ or FISH -)
4. Patients must be eligible to receive adjuvant chemotherapy as defined by a good Karnofsky index, no hematological, cardiological or hepatic contraindications nor any impeding comorbidity.
5. Patients must have given a written informed consent.

Exclusion Criteria:

1. T3 or T4, HR-, N+ (except pN1 (mi) (sn), Her2+ (IHC 3+ or Fish+) patients.
2. Metastatic patients.
3. Patients who cannot give an informed consent.
4. Patients who cannot receive chemotherapy.
5. Patient who participated in another clinical trial and is still in the exclusion period of any other trial.
6. Mentally disabled patient who has no legal responsibility for herself.