Breast Cancer Update, Issue 2, 2016 (Video Program) - Video 8Role of the 21-gene signature assay for patients with invasive lobular carcinoma
4:42 minutes.
TRANSCRIPTION:
DR DICKLER: Invasive lobular carcinoma represents roughly 10% of breast cancer. The rest is really made up of invasive ductal carcinoma. And invasive lobular carcinoma is typically strongly estrogen and progesterone receptor-positive and typically HER2-negative, although there are obviously exceptions. And I think that there’s a lot of ongoing investigation in invasive lobular carcinoma to try and understand it and how it differs from invasive ductal carcinoma. But I think at the present time we treat the two the same, in that we use tumor size and lymph node status as well as expression of the estrogen and progesterone receptor by immunohistochemistry and HER2 by either IHC or FISH to guide adjuvant treatment recommendations. DR LOVE: Now, what about this particular paper, because it looked like you all went back and tried to look at the cases of lobular cancer, in particular this issue of patients who had a Recurrence Score® done, or a genomic assay. Can you talk a little bit – I assume the big issue in terms of genomic assay with lobular carcinoma is, are they all so benign ER-positive that none of them need chemo? Or can you identify people who benefit from chemo? Is that kind of the issue? DR DICKLER: Yes. So we do treat it the same, and yet we’re frustrated by that, because there’s likely a different biology. And there is a somewhat different natural history of the disease in that, given the fact that it’s strongly estrogen and progesterone receptor-positive, it often has an indolent time course. And we often think that it’s most likely sensitive to endocrine therapy. And so the natural question is, do you really need chemotherapy in patients with invasive lobular carcinoma? And so we went back and did the Recurrence Score on invasive lobular carcinomas at Memorial Sloan Kettering Cancer Center. And interestingly, very few actually had a high Recurrence Score. But it was really notable how few really had a high Recurrence Score. DR LOVE: The one thing is, though, a significant number had an intermediate Recurrence Score. DR DICKLER: Correct. DR LOVE: I mean, 35% had intermediate. You’re right. Very few, less than 2%, had high, but a lot had intermediate, where there really is a question. The thing that I thought was interesting is looking at your paper when you went back and went through the case, it looked like, in most of these cases, the majority, the Recurrence Score actually factored into the decision. DR DICKLER: Yes. We often say, “Don’t get a test unless you’re going to use the result.” And that, I think, is just a good rule in medicine in general. And so most of us will order the Oncotype if we think it’s going to be useful in that case. And typically for our intermediate-risk patients, we try to have a balanced discussion about what we know, what trials are ongoing in this setting, the uncertainties as to whether chemotherapy is beneficial in this subgroup and then make an educated decision with the patient as to whether we should add chemotherapy or not. DR LOVE: And, of course, in the low Recurrence Score patient, we saw the TAILORx study initial group of low Recurrence Score, they had a great prognosis, but we’re waiting on the intermediate to see if they benefit from chemo. So you could look at your data and say that maybe a third of these patients had intermediate scores that you would at least consider chemo. And the TAILORx paper that Joe Sparano reported in The New England Journal of Medicine defined the low-risk group. Remember, I think it’s 10 and below. So although TAILORx is a very important trial, particularly in the intermediate-risk group, we are going to struggle with the results in that it’s different than the groups that were defined initially, which included everybody up to 18 into that low-risk group, whereas really the 11 to 18s are randomized in TAILORx. So although that’s a very, very important study, it’s going to provide essential data, but it’s not going to completely answer the question as to what we do with the patients from 11 to 18 who are being randomized. Yet historically, we’re considering them low-risk. |