Michael D. Alvarado, MD: The Oncotype DX Breast Recurrence Score test has been used now for almost 14 years to look at ER [estrogen receptor]-positive breast cancers, and originally at early stage breast cancers. It was originally designated for node-negative patients. Obviously, since that time, it has now been incorporated into node-positive patients, but it really was used to determine what the likelihood is that a woman would benefit from the addition of chemotherapy to hormone therapy for these ER-positive breast cancers.
The recurrence score is used for women who have ER-positive breast cancers. Specifically, it’s utilized to determine what the risk is of that cancer and to understand the biology of that breast cancer because once we know the biology, we can better determine what is the best adjuvant therapy. Should that just be hormone therapy, or should that woman also get chemotherapy? So really, it’s specifically used to predict chemotherapy benefit but at the same time give prognosis for that patient.
The Oncotype recurrence score is a genomic assay that’s based on 21 genes and specifically, 16 cancer-related genes. When this recurrence score was first developed and became available for patients, there was some consideration that maybe oncologists could predict what the recurrence score was going to be based on characteristics such as the grade of the tumor, the size of the tumor, or even the age of the patient. Another characteristic that pathologists use is something called the Ki-67 protein. Sometimes, oncologists felt they could predict the recurrence score based on Ki-67. However, over the last 10 or 12 years, there have been a number of studies that have shown—regardless of Ki-67, the grade of the patient, or their age—you really can’t predict what the recurrence score is going to be. In the clinic, physicians and oncologists need to realize that even though they may have a sense that maybe this is a low-risk tumor, it really still can be a high recurrence score tumor, or even vice versa.
Previously, we had used a number of prognostic factors to help understand what the future risk was for women diagnosed with early stage estrogen-positive breast cancer. Those factors were things like tumor size, patient age, and the grade of that tumor. However, we realized that wasn’t the best way to understand the risk for these patients. Really, these genomic assays like the recurrence score better predict and prognosticate for these patients.
Now having said that, it is important to understand that these other clinical factors, such as age, tumor size, and grade, can also be used with a genomic assay for better prognosis. However, even more importantly is that the prediction of chemotherapy benefit that is gotten from the recurrence score does not change with these prognostic characteristics. It is a good way for prognosis to combine both the genomic assay and these other clinical factors, but when it comes to chemotherapy prediction, it truly is just the genomic assay itself.
When utilizing the genomic assay, the recurrence score, you should also keep in mind other factors such as the patient’s age, tumor size, and potentially grade. Now, these are sometimes important for determining adjuvant therapy when patients have, for example, a lower recurrence score. If a woman has a low recurrence score and she’s not going to benefit from the addition of chemotherapy, it is possible to use these other prognostic factors, such as age and tumor size, to potentially change or augment the type of hormone therapy that patient might receive. You can use these prognostic characteristics in conjunction with the recurrence score, but again, they’re not used to determine chemotherapy benefit but rather to potentially augment the type of endocrine therapy that patient might receive.
There are definitely going to be cases that oncologists see that are at what I call the periphery of the range of biology. For example, for a woman in the age category of 75 to 80 years old who has a sub—1-cm tumor that is strongly estrogen receptor-positive, progesterone receptor-positive, and grade 1, it’s highly likely that that recurrence score is going to be low risk. In that case, it may not be cost effective or helpful to order the recurrence score in this type of patient. Again, for someone who has a very small cancer and is older, in the 70-to-80-year-old age group, it will almost always be low risk. There are some cases where you can probably avoid utilizing the recurrence score, but it’s a very small number of cases.
Transcript Edited for Clarity