- One in four patients with T1abN0 breast tumours of less than 1 cm can benefit from adjuvant chemotherapy.
Why this matters
- The study challenges the assumption that all patients with small breast tumours clinically classified as low-risk can avoid adjuvant chemotherapy after surgery.
- 826 of 6693 patients with pT1abN0 breast tumours enrolled in the MINIDACT study had both their genomic risk and clinical risk for recurrence assessed using MammaPrint®, a 70-genes signature test, and Adjuvant!, a suite of online tools.
- Patients were randomly assigned to receive or not receive chemotherapy and were followed for 5 years.
- Funding: European Organisation for Research and Treatment of Cancer.
- 99.3% of the patients were clinical low-risk; 75.5% were clinical low-risk and genomic low-risk.
- 23.7% were clinical low-risk and genomic high-risk.
- 5-year distant metastasis-free survival for clinical low-risk/genomic high-risk group who received chemotherapy was 97.3% (95% CI, 89.4-99.3) versus 91.4% (95% CI, 82.6-95.9) for those who did not.
- 5-years distant metastasis-free interval and overall survival for clinical low-risk/genomic high-risk group treated with chemotherapy were 98.8% (95% CI, 91.9-99.8) and 98.5% (95% CI, 89.6- 99.8), respectively versus 91.4% (95% CI, 82.6- 95.9) and 95.8% (89.1- 98.4%), respectively for those who did not receive chemotherapy.
- Small sample
- Genomic test sensitivity is still low.
- A small group of patients had benefits but a still large number of patients received chemotherapy without apparent personal benefits.