Insights By: Terry P. Mamounas, MD
The results of the TAILORx trial that were presented in 2019 showed that clinical risk refines the results of the Oncotype DX recurrence score in terms of prognosis. In other words, in the multivariate analysis, clinical pathologic factors—clinical risk in other words—does correlate with outcome in addition to recurrence score. But what the TAILORx also showed is that the benefit from chemotherapy does not depend on the clinical pathologic factors, but rather it depends on the recurrence score pretty much exclusively.
The clinical pathologic factors, from TAILORx, do impact prognosis, but they do not impact benefit from adjuvant chemotherapy. The benefit of adjuvant chemotherapy was the same whether you had low clinical risk or high clinical risk. In the majority of those patients from TAILORx, that was the case. There was not much benefit from chemotherapy for patients with a low recurrence score, even when they had low or high clinical pathologic factors.
But for the intermediate group and up, clinical pathologic factors do affect prognosis, but they do not affect benefit from chemotherapy.
The SEER [Surveillance, Epidemiology, and End Results] data combined with recurrence score information was a major endeavor that allowed us to study thousands of patients who had a recurrence score and also clinical pathologic characteristics that were included in the SEER registry and also had the recurrence score information from the Oncotype DX test.
With these results we’re able to look at hundreds and thousands of patients who actually have this clinical information as well as the recurrence score information. What these data show is that for even, for woman under the age of 50 years, the recurrence score is very prognostic of outcome. For the SEER data, the outcome was breast cancer–specific survival. Essentially what the data showed are that even if you’re under 50 years but you have a recurrence score under 25, you can have a very good outcome, whether you had negative nodes or positive nodes. Age was not a significant predictor of outcome for that population of patients, who did very well if they had a recurrence score of less than 25. For the patients who had a recurrence score of over 25—and these were patients who did not receive chemotherapy.
The decision to give chemotherapy wasn’t randomized in the SEER data. It was per clinician recommendation. But even without chemotherapy, there were very good outcomes for a woman under 50 years with a recurrence score of less than 25, and a higher risk for patients over 25, which we knew from previous data sets.
We can tell patients under 50 years who have a low recurrence score that their outcomes are very good because of the recurrence score, but the outcomes are not so good if their recurrence score is high. Age by itself is not a criterion that you should give chemotherapy, even if you’re node negative and perhaps if you have 1 to 3 positive nodes. If you have a low recurrence score, the outcomes are very good, and chemotherapy benefit is very unlikely if the outcomes are so good because obviously you can only improve 1% or 2% risk by very little by giving chemotherapy, and in most cases, not at all.
The recurrence score has made a significant impact in the decision-making process for how we treat patients. This is because it provides us with good certainty in terms of their prognosis, and it provides us with a very good certainty in terms of benefit from chemotherapy. I think that is perhaps the most important component because if you tell a woman your risk is X, Y, or Z, it could be lower or higher, but if you tell her that there is no benefit from chemotherapy and we have strong evidence to that, there’s absolutely no reason for a woman to receive chemotherapy.
So those results are very instrumental in helping us make decisions in terms of who we treat with adjuvant chemotherapy and who we do not.
The genomic profile for the last 15 years has revolutionized how we approach patients with early stage breast cancer, namely those with estrogen receptor-positive, HER2 [human epidermal growth factor receptor 2]-negative disease and mostly those who are node-negative and also with a low number of positive nodes. It has made a big impact in terms of who we treat with chemotherapy and who we do not, and it has resulted in the use of chemotherapy diminishing significantly over the past 15 years without giving up any benefits. This is because the majority of the patients who we don’t treat with chemotherapy would not have benefitted from chemotherapy. So there’s a major impact in how we approach and treat patients.
Transcript Edited for Clarity
Barbara Jacoby is an award winning blogger that has contributed her writings to multiple online publications that have touched readers worldwide.