The Impact of the Gene Recurrence Score on Chemotherapy Prescribing in ER Positive, Lymph Node Positive Early Stage Breast Cancer

Inclusion Criteria:

General Inclusion Criteria (All Patients)

1. Age 18 years of age or older
2. ER Positive Tumours (≥1% positive cells or Allred score ≥ 2 (Appendix 1))
3. Human Epidermal Growth Factor Receptor 2 (HER2) negative breast cancer (0-1 by IHC or FISH \<2.0)
4. No evidence of metastatic disease on CT, bone scan or other imaging
5. Fit for consideration of chemotherapy as determined by the Investigator
6. Adequate performance status (Eastern Cooperative Oncology Group (ECOG) 0 or 1 (Appendix 2))

Inclusion Criteria - Cohort 1 (Postoperative Patients): N= 75

1. Adequate surgical excision of breast tumour (mastectomy or lumpectomy) and lymph nodes (sentinel lymph biopsy or axillary dissection)
2. Any tumour size (T stage (Appendix 3))
3. Involvement of 1-3 lymph nodes (N1, including micrometastases)

Inclusion Criteria - Cohort 2 (Preoperative Patients): N= 75

1. Candidates for preoperative therapy for early breast cancer
2. T2-T4 tumours
3. Involvement of at least one lymph node, (including micrometastases) on biopsy
4. Adequate tissue from core biopsy for 21 gene RS testing (approximate minimum 5mm)

Exclusion Criteria (All patients):

1. ER negative tumour (Allred score 0-1)
2. HER2 positive tumours as defined by IHC 3+ or FISH ≥ 2.0
3. Node negative disease, including those with Isolated tumour cells only (node negative i+/i-)
4. Known metastatic breast cancer
5. Performance status ≥ 2
6. Patients not considered by their treating physician to be fit to undergo chemotherapy.
7. Men with breast cancer.