You are looking here at DCIS and specifically you’ve got a study on mastectomy. What was the big issue that you were challenging, that you were taking on here?
Traditionally ductal cancer in situ which is large has been treated by simple mastectomy, the skin is removed, and the recurrence rate is less than 1%. There is data published from a large number of patients in the Sloane Study in the UK confirming that. There has been an increasing tendency to reconstruct the breast after DCIS which leaves a lot of skin on and quite often thick flaps on that skin. So the recurrence rate has been going up. So we looked and we found that the recurrence rate in our simple mastectomies was nil in a ten year period; for those with skin sparing mastectomy it was up at 5.6%. What that’s saying is that you have to be very careful that the margins are actually clear after mastectomy with skin sparing mastectomy because close margins has the same prognostic import predicting recurrence as if you did breast conserving surgery and you left close margins. But with breast conserving surgery most people give radiotherapy and they don’t give radiotherapy after mastectomy.
So you’ve done a study, you’ve got a clear result, what are the clinical implications for surgeons and doctors?
I think we have to realise that the reason recurrence rate after mastectomy has been falling has been better surgery, clearer margins and adjuvant therapy. We, on the whole, don’t give adjuvant therapy for DCIS. But there is another message in here: more DCIS is HER2 positive; if you look at the mastectomies, the population that have a mastectomy, the ER negative DCIS is 40-50% of the mastectomies. So we don’t currently give adjuvant therapy, we don’t look at ER for DCIS but what’s emerging is it’s the ER negative HER2 positive DCIS that recurs early in the first five years after surgery and that actually you need to be very clear you’ve got clear margins there and we might need to think a lot harder about getting ER and looking at ER and using ER for treatment in that setting.
Would you make any practical recommendations right now on the basis of the evidence you have so far?
On the basis of the evidence we have so far you need to measure the ER status of the DCIS. If it’s ER negative, and you know that pre-op, you need to be very clear about margins. You need to go back if the margins are involved and clear them surgically and, actually, one of the things we haven’t done but they do in the US is you need to think about post-reconstruction mammograms because, actually, if you leave a lot of breast tissue you can pick up early recurrence of DCIS on post-reconstruction mammograms. And if you don’t pick it up early it will present as invasive occurrence, require chemotherapy, require radiotherapy and there is a risk you’ve lost life.
So, to summarise, what would you say to doctors about your study on DCIS surgery and also the importance of ER?
ER is a predictor of early recurrence in the first five years if the patient has got ER negative DCIS. In the context of breast conserving surgery it’s less of a problem because you give radiotherapy. We historically don’t give radiotherapy after mastectomy because there’s a low risk of recurrence. Skin sparing mastectomy with close margins you need to think very hard if it’s an ER negative cancer and you need to consider re-excision if the margins are involved after the surgery.