Benefits of Genomic Testing in Breast Cancer

Transcript:Hope S. Rugo, MD: The Breast Cancer Index is an interesting test because, again, I think it has the best data in terms of predicting those who might benefit from ongoing hormone therapy, although the data are a selected small group of patients from MA.17, so we have to be cautious about that. It doesn’t matter when you do the test. You could do the test when a patient first comes in, or you could do the test at 5 years, and I would be probably most likely to do the test later out. The tumor is sitting there. Nothing’s happened to it, and the data have been obtained from tumors that were stored in paraffin for a fairly long period of time. So, I think that that’s okay. Normally, it might not be advantageous to know that information up front just because it might be overwhelming to the patient. And, I don’t know that that’s going to change what you do up front, necessarily.

There are some data that the Breast Cancer Index could be used up front, but I’ve tended to use some of the other genomic tests, simply because there are a little more data and they came out first. Have I used the Breast Cancer Index in my population of patients? In our clinic, we started to, especially since MA.17R started to use the test in women who fall into this intermediate risk, who I’m on the fence about extending adjuvant hormone therapy or not. I’ve had a couple of women even inquire, so I’ve sent the test in a few women, as have my colleagues.

I do expect, however, that my use of the test may increase over time, depending on the data from the NSABP B-42 trial because I think that the balance of risk-toxicity versus benefit is so incredibly important for our patients. And, even though those quality of life measures didn’t show any difference, I have a hard time believing that it’s really the case. If you look at the quality of life from the TEXT and SOFT trials, it also looks like quality of life was relatively similar whether you got ovarian suppression or not, whether you took an AI versus tamoxifen. And it’s just not true in clinical practice. So, it may be that our quality-of-life tools can’t really pick up those. That finesse of difference that women see, it’s very hard to get that reported in a meaningful way in our current tools.

There are groups of patients, as we’ve discussed, who might benefit from extending adjuvant hormone therapy. And then, there are groups of patients who we know we don’t need to do that—tiny cancer, low grade, no extended adjuvant hormone therapy. For patients with a big cancer, lots of tumor in nodes, high risk, we’re going to extend adjuvant hormone therapy. But, then there’s this big group in the middle that you just really don’t know—maybe a T2 tumor, maybe one node positive. You’re on the fence. Should you recommend they take hormone therapy for longer or not? And, that’s the group of patients where we most need a test to try and help us differentiate who’s more likely to benefit versus not.

Ruth O’Regan, MD: As far as patients who would be candidates for molecular analysis of their cancer to determine the risk of late recurrence, I think, overall, most of us tend to think about extending therapy in patients who we think are at higher risk, so patients with node-positive breast cancer, for example. I think if you have somebody with a node-negative breast cancer, it’s still very worth considering doing some kind of molecular testing to see if you could estimate whether they have a significant risk of recurrence years 5 to 10. I have to say, overall, for most patients—both node-negative and certainly node-positive—I would consider ordering one of those molecular assays to determine whether they’re going to benefit from more treatment or not. The problem is the assays that we have right now need further validation before we can just use it on every patient.

The other thing I think to keep in mind is that if you have a patient who perhaps had a lot of lymph nodes positive who wants to stop the endocrine therapy, using something like the Breast Cancer Index to tell them their risk years 5 to 10 would be useful in terms of trying to keep them on the medication, and certainly I’ve done that before, as well. I think what’s a little bit less clear is whether you have somebody that’s at high risk because they have node-positive disease, but comes back with one of the assays showing that they have a very low risk of recurrence years 5 to 10, whether we’re comfortable really accepting that data and taking them off the medication at that time point or not. So, I think we’ll get more data, but, at this point, the Breast Cancer Index probably would be the one that would give you the most information in that setting.

Transcript Edited for Clarity