Dorothy has invasive breast cancer and mixed tumour characteristics. What now?

Dorothy, a 76-year-old postmenopausal woman, was diagnosed with cT2N0 breast cancer in the left breast (2.5 cm). Apart from mild hypertension and osteopenia of the lumbar spine, she is otherwise healthy (ECOG PS 0). She underwent breast conserving surgery with sentinel lymph node biopsy.

Histology report:

• 1.5 cm ductal invasive carcinoma (NOS – not otherwise specified) and another foci of 7 mm  of the same histology type, 5 mm apart from to the larger tumour; both tumours were included  in the same specimen and excised with “clear” margins
• All 3 sentinel lymph nodes were negative
• Larger tumour:
  • Grade 1
  • ER positive (100%), PgR negative (0%)
  • HER2 staining negative (1+)
  • Ki67 score 20%
  • No lymphovascular invasion
• Smaller tumour: similar but Ki67 score 15%

The tumour board decided to treat the patient with radiotherapy and systemic therapy. In view of some of her clinical-pathological parameters (negative PgR, marginal Ki67 of the larger tumour and a fit patient capable for chemotherapy if needed), the tumour board decided to perform  the Oncotype DX® assay. The assay was firstly performed in the larger tumour and showed a Recurrence Score® result of 34; no further Oncotype DX® assay analysis of the smaller tumour was performed.