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Case history

image A 45-year-old woman presented with a symptomatic 3 cm left-sided breast lump in October 2015. A core biopsy demonstrated invasive breast carcinoma. She had a left wide local excision and sentinel node biopsy; pathology demonstrated a 29 mm grade 2 invasive ductal carcinoma with associated ductal carcinoma in situ, which did not increase the whole tumour size. There was no lymphovascular space invasion and none of the five sentinel lymph nodes contained cancer. Receptor status was oestrogen receptor (ER) Allred score 7, progesterone receptor (PR) score 0, human epidermal growth factor receptor 2 (HER2) 1+ staining on immunohistochemistry (negative).

She had experienced an early menopause at age 40 due to endometriosis and she had been on hormone replacement therapy in the past. She had no other medical history or family history of note.

Using the PREDICT tool (,1 her overall survival (OS) at 10 years with surgery alone was estimated at 87%. This improved to 90.2% with the addition of adjuvant hormone therapy, and to 94% with the further addition of adjuvant third generation chemotherapy (i.e. 3.8% additional benefit of chemotherapy).

At her oncology clinic visit, the patient was ambivalent about adjuvant chemotherapy. The oncologist discussed the potential benefit of adjuvant therapy suggested by the PREDICT tool and the additional information using the Oncotype DX test (Genomic Health, London, UK). It was agreed to proceed with this test and, if the result of the test result suggested a high risk of recurrence (a score of 32 or higher), the patient would accept adjuvant chemotherapy in addition to hormone therapy and radiotherapy. Conversely, if the test result indicated a low risk of recurrence (a score of 17 or lower), only adjuvant hormone therapy and radiotherapy would be recommended. If the test result suggested an intermediate risk (a score between 18 and 31), she agreed to accept chemotherapy if her score was greater than 25.

The Oncotype DX score was 27, with an estimated 18% risk of recurrence at 10 years with surgery and 5 years of tamoxifen (data from the National Surgical Adjuvant Breast and Bowel Project [NSABP] B-20 trial2). The patient consented to receive six cycles of adjuvant anthracycline-based chemotherapy.

What is Oncotype DX?

What is the rationale for Oncotype DX testing?

How has Oncotype DX been validated for clinical practice?

Which patients benefit from Oncotype DX testing?

What is Oncotype DX?

Oncotype DX is a 21-gene expression assay which is performed on formalin-fixed paraffin-embedded breast cancer tissue specimens. It was developed to provide additional prognostic information about a cancer above and beyond classical clinicopathological features such as ER status and lymph node involvement. The Oncotype DX assay measures the levels of expression of 16 tumour-associated genes and five reference genes, and, using an algorithm, produces a result expressed as a recurrence score between 0 and 100. Higher expression levels of 'favourable' genes such as ESR1 would produce ...

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