Adjuvant Therapy for Breast Cancer

Transcript:Adam M. Brufsky, MD, PhD: We’ve talked a lot about metastatic disease. We’ll end with some comments on some very important abstracts that are being presented at this year’s ASCO meeting, in terms of adjuvant therapy for breast cancer. Kim, you hinted at the first one of those, which is the MA17R study. Could you summarize that for us?

Kimberly L. Blackwell, MD: Yes. We’ve all been waiting for the results of MA17R for quite a long time. I think, if I remember correctly, we had the results of MA17 in 2002.

Adam M. Brufsky, MD, PhD: It was published in 2003.

Kimberly L. Blackwell, MD: 2003. So, this is 13 years in the making. That’s a dedicated study team. But the bottom line is they took postmenopausal women who had early-stage breast cancer and had completed 5 years of tamoxifen, 5 years of letrozole, and then I think it was roughly about 800 patients that then got randomized.

Sunil Verma, MD, MSEd, FRCPC: A thousand.

Joyce A. O’Shaughnessy, MD: 1918.

Kimberly L. Blackwell, MD: That got randomized, after 10 years, to either continuing the letrozole or continuing on placebo; it was a blinded study. And basically what the study demonstrated was roughly about a 2% absolute difference in disease-free survival in favor of continuing the letrozole past the 10th year. There’s another presentation at this meeting showing that there’s no impact of continuing that on quality of life, as best as they could ascertain. So, I think I was a big early adapter to 10 years of endocrine therapy. I’ve hinted at it throughout our discussion this morning, and, at least for my patients who are doing well who have adequate bone health—whether they’re on a bone health agent or not—I will discuss continuing it past the 10th year.

Joyce A. O’Shaughnessy, MD: Data will be coming out later today. But what I’ve seen just written in summary so far was a 4% difference at the 5-year mark, 95% with letrozole.

Adam M. Brufsky, MD, PhD: Which is the absolute 15-year mark. It’s the 5-year mark of the trial.

Joyce A. O’Shaughnessy, MD: Yes, and 91% with placebo in terms of the patients.

Kimberly L. Blackwell, MD: So, 4%, sorry.

Joyce A. O’Shaughnessy, MD: Yes, 4% remain NED (no evidence of disease), so a hazard ratio of 0.66, a 34% reduction in recurrence.

Adam M. Brufsky, MD, PhD: But, the key is, when you say recurrence, it’s in DFS. And remember, I’m guessing—at least looking at the data that I’ve seen so far—that the DFS is mostly new contralateral breast cancers and not really metastatic disease.

Joyce A. O’Shaughnessy, MD: No, it’s 0.2% with letrozole, 0.4% with placebo contralateral. So, there’s a benefit, but it’s not accounting for this 4% difference.

Sunil Verma, MD, MSEd, FRCPC: But, it will be really interesting.

Adam M. Brufsky, MD, PhD: To see it, yes.

Sunil Verma, MD, MSEd, FRCPC: From a quality of life perspective, these were women who were prepared to be randomized after 10 years of endocrine therapy to go for an additional 5 years of treatment or not. So, is there a selection process as to who those women were? We’ve always said, “Okay, you know what, it hasn’t been that bad.” I can go another 5 years, so I’m not sure how much to put the emphasis on the quality of life. It will be really interesting how they report it. But, yes, to me, the most clinically impactfulness is not in this patient group, it’s 5 years of tamoxifen and 5 years of letrozole; another 5 years of this treatment. The question, from a clinical context, is what to do for those patients who have had 5 years of an AI (aromatase inhibitor) who come to us and who have not had prior tamoxifen. This shows that there is ongoing benefit of aromatase inhibitor beyond 5 years.

Adam M. Brufsky, MD, PhD: It predicts B42, which is going to probably be announced at San Antonio, right?

Sunil Verma, MD, MSEd, FRCPC: I think this sort of justifies the rationale to continue an AI suppression.

Kimberly L. Blackwell, MD: I think I’ll go home from the meeting—whereas before I would say to patients, “There are no data that you should have to take this drug past 10 years”—and say now, “There are fairly good data that continuing past the 10th year might offer you an additional benefit.”

Carlos L. Arteaga, MD: Yes. I just hope we don’t see a 15- versus 20-year trial.

Adam M. Brufsky, MD, PhD: We may.

Carlos L. Arteaga, MD: And I want to bring up a point that is perhaps philosophical and that I’ve reflected upon. As a community, we should do better than this. I’m happy, and I celebrate the people that benefit from this trial. I’m happy that the quality of life was not affected, although there was a clear selection process going on for a decade. But, I think that I would hope that as we identify targeted therapies that trump that later recurrence, we should be cutting back on the length of therapy.

Adam M. Brufsky, MD, PhD: Selection. Again, probably in the interest of time tonight, we don’t have the time to talk about even selecting people for therapy. Maybe there are luminal A patients who don’t need anything, that were minimal therapy and 3, 5 years, that’s it.

Transcript Edited for Clarity