A 10 year service evaluation of the survival of 439 patients with early oestrogen receptor positive breast cancer who underwent initial OncotypeDX ® testing to guide adjuvant chemotherapy decisions

Objective: To explore the long-term outcome of patients who underwent Oncotype DX® testing. The relationship between the RS, adjuvant treatments received, and clinical outcomes across the entire range of RS results are reported.

Methods: 10-year Kaplan-Meier estimates for distant recurrence/BC-specific survival (BCSS) in this cohort. The analysis included 439 patients. The follow-up time ranged from 14 to 142 months. All analyses were performed using the SPSS v20.

Results: More than half of patients had low RS (<18) (55.6%) and 15.3% had RS ≥ 31. Chemotherapy use was consistent with the RS with 4.4%, 7.1%, 28.0%, 71.4% and 91.0% receiving adjuvant chemotherapy in patients with RS < 11, 11-17, 18-25, 26-30, and ≥31, respectively. The overall chemotherapy rate was 27.6%. Distant metastasis free survival (DMFS) differed significantly (P < 0.001) between the RS groups with 10 year DMFS rates of 99% (SE +/- 0.01) in the RS<11, 97% (SE +/- 0.03) in the RS 11-17, 97% (SE +/- 0.02) in the RS 18-25, 85% (SE +/- 0.1) in the RS 26-30 and 74% (SE +/- 0.08) in the RS ≥ 31 group. Ten year breast cancer specific survival also differed significantly (P < 0.001) between the RS groups; this risk was 100% (no deaths from breast cancer reported in the first 10 years) in RS < 11, 95% (SE +/- 0.03) in RS 11-17, 94% (SE +/- 0.04) in RS 18-25, 93% (SE +/- 0.07) in RS 26-30, and 79% (SE +/- 0.07) in the RS ≥ 31 group.

Conclusions: Use of Oncotype DX RS does guide the treatment decisions and correlates with the BCSS and disease-free survival for ER positive, Her2 negative, early-stage, node negative breast cancer patients.