Use of the Oncotype DX^® test for therapeutic decision-making in the context of treating invasive breast cancer

Approximately 6 000 new cases of breast cancer are diagnosed in Québec each year, most of which are hormone-dependent. To treat this type of cancer, hormonal therapy (HT) is generally prescribed after surgery to reduce the risk of recurrence, sometimes with adjuvant chemotherapy (CT) when the benefit of adding it is considered to outweigh the risks involved. The Oncotype DX^® (ODX) gene expression test, which came on the market in 2004, joined the available tools for helping clinicians in this therapeutic decision-making. The test, which is performed on a tumour sample, measures the expression of 21 genes, and the result indicates the patient's individual risk, that is, the probability that she will experience a distant recurrence during the 10 years following surgery.

The ODX test, which is performed only in the manufacturer's laboratory in the United States, is covered by the Régie de l'assurance maladie du Québec (RAMQ) in certain conditions defined in terms of reference drafted by the Direction générale de cancérologie (DGC). Given the high cost of this test and questions raised about its value-added in the literature, the DGC asked INESSS to assess the test's clinical utility and value-added and to then update the terms of reference for its use.