Margaret underwent breast conserving surgery, what now?

Margaret, a 57-year old postmenopausal woman had an abnormal screening mammogram showing a mass in the left breast. Breast conserving surgery (BCS) with sentinel lymph node excision revealed the following:

• A large 3.1 cm grade II invasive carcinoma of no special type (NST)
• The two sentinel lymph nodes were negative
• Both estrogen (85%) and progesterone (75%) receptors were positive
• HER2 staining was negative
• No vascular or lymphatic channel invasion was found
• Staining for Ki67 revealed 30% positive tumour cells

The tumour board recommended an anthracycline and taxane-based adjuvant chemotherapy due to high clinical pathological parameters such as large tumour size and high Ki67 levels. Since the patient was reluctant to have adjuvant chemotherapy, an Oncotype Dx assay was performed and showed a Recurrence Score® result of 20.