Improving decision-making for post-operative, postmenopausal women with oestrogen-receptor positive early breast cancer.

The vast majority of women with breast cancer have oestrogen-receptor positive tumours. After their surgery, these patients will almost always be treated with endocrine however not all will require chemotherapy.

This decision is usually based on an assessment of risk factors related to the tumour, its biology and the patient. There are multiple tests available that can help clinicians and patients to determine what the risk is of the cancer relapsing. One such test is called the Oncotype DX Recurrence Score. This test is very expensive (approximately $4000) and it not funded by Medicare and therefore remains inaccessible to most patients. This study evaluates a novel test called the IHC4+C score which estimates risk of the cancer coming back. For example, a risk score of 5% means that there is a 5% risk that the cancer could come back over the next ten years if the patient takes their endocrine therapy (and does not have chemotherapy). This score helps to decide whether chemotherapy should be recommended.

In the case of a score being 5%, this is considered a low risk score; hence it is unlikely that chemotherapy would be recommended to this patient. This test has been shown to provide similar information to the Oncotype DX but has the advantage of being affordable and routinely available. When used to help make treatment decisions, this test has been shown to result in less patients requiring chemotherapy.