What is an Oncotype Dx score?
It is a new way of assessing recurrence risk in Breast Cancer, and selecting patients for whom chemotherapy would be useful to decrease that risk, after curative surgery. Previously, we were recommending postoperative chemotherapy in most sizes of tumors larger than 1 cm, or whose estrogen or progesterone receptors were low, or grade was high. Some fraction of those didn’t really need it. We didn’t have a tool to tease out those who would truly benefit vs. those who would not.
It is a genetic profile of the patient’s cancer cell. It looks for 21 genetic characteristics, and assigns a numerical score of relapse probability. It that falls in the Low Risk Category, there is no benefit to adding chemotherapy. In the High Risk Category, there is clear benefit in reducing recurrence rates. The Intermediate Category is a grey zone, and the benefit of chemotherapy has not been validated. The decision of whether to do post operative, preventive chemotherapy becomes an individualized one.
Should it always be done? Only if there is a question about whether or not to add chemotherapy. If the answer is clear, then not. Or if a woman is clear that she wants to do chemotherapy for a chance that it might help. But if we are on the fence about the value of additional chemotherapy, then the Oncotype Dx score helps make the decision. There are other gene profiling tests that are used in Europe, e.g. Mammoprint, which use much larger gene signatures.
There are scores being developed for other cancers, e.g. Colon cancer, where again the decision to do chemotherapy in the postoperative situation falls in the grey zone. It has been beneficial only in some instances of Stage ll disease. At the moment we use rough, clinical characteristics to guide us in that decision. An additional tool that predicts a recurrence score would be very helpful in making choices of treatment.