Early Stage Breast Cancer: TAILORx Trial



Terry P. Mamounas, MD: The TAILORx trial was a large phase III randomized clinical trial comparing adjuvant endocrine therapy to chemotherapy plus adjuvant endocrine therapy for patients who had an intermediate Oncotype DX recurrence score. The rationale behind the trial is that when we evaluated chemotherapy benefit in an old NSABP [National Surgical Adjuvant Breast and Bowel Project] study, B-20, it appeared that benefit from chemotherapy was large in patients who had a high recurrence score and nonexistent for patients who had a low recurrence score. But that left us in the middle with an intermediate-risk recurrence score category, for which we weren’t quite sure if there was a benefit from chemotherapy or not. The TAILORx study was designed to take a large number of these patients and randomize them to chemotherapy plus endocrine therapy or endocrine therapy alone to show whether there is or isn’t benefit from adjuvant chemotherapy for that population to then better define who we should treat with the adjuvant chemotherapy.

The TAILORx study was very impactful because it gave us a very definitive result, essentially that there is no benefit for chemotherapy for patients with a recurrence score of 11 to 25. Now we can define the cutoff when we start adjuvant chemotherapy with a recurrence score of 25 or more.

However, there was a little bit of an interaction with age. Patients who are younger than 50 years appeared to receive some chemotherapy benefit, even if they had a recurrence score of 16 to 25. The TAILORx helped us define who needs chemotherapy, who doesn’t. But it’s not necessarily the same population for patients over the age of 50 years and in patients under the age of 50 years. Under the age of 50 years, the cutoff where we consider chemotherapy is a recurrence score of 16—or 11 at least, but more importantly 16. But for women over 50 years, the cutoff is 25 or higher where we would recommend chemotherapy, under 25, we would not.

TAILORx again was very instrumental in actually defining cutoffs because before TAILORx, we were very uncertain about what to do with patients with a recurrence score of 11 to 25. We ended up giving them chemotherapy just to be safe. But with TAILORx, we have very strong data to suggest that for a woman over 50 years with a recurrence score under 25, there’s no benefit from chemotherapy. For a woman under 50 years with a recurrence score under 16, there’s really no benefit, and for sure under 11 we knew there was no chemotherapy benefit because those patients were treated with endocrine therapy alone in TAILORx.

In terms of prognosis, the recurrence score is very prognostic of outcome for sure. However, clinical pathologic factors also play a role in addition to the recurrence score. For example, if you have a recurrence score of 10, you have X-risk of recurrence at 10 years. If your tumor is 1 cm versus if your tumor is 4 cm, the risk of recurrence is a little bit different. Obviously it will be more for a tumor of 4 cm versus 1 cm. So you do not eliminate clinical pathologic factors for the prognostic algorithm, but the recurrence score is more important than those factors, and it has to be in the algorithm to better define prognosis.

The results of the TAILORx trial actually gave patients certainty in terms of making a decision regarding chemotherapy or not. Before TAILORx, for a recurrence score of 11 to 25, we were not sure if chemotherapy should be used or not. We ended up giving it because we didn’t have any data. But now that we have the data, we can with certainty tell patients that under 25, if you’re over 50 years, you’re not going to benefit from chemotherapy, and therefore you should not take it. Even if you’re under 50 years, and if you have a recurrence score under 16 pretty much, there’s not much benefit for chemotherapy. Therefore you should not get it.

The cutoffs may be a little bit different between younger and older patients, but it gives patients certainty in making a decision regarding chemotherapy use.

Transcript Edited for Clarity

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