2011 SABCS, San Antonio Breast Cancer Symposium, 6-10 December, San Antonio, USA

Treatment of breast cancer as a chronic disease

Dr Vered Stearns – John Hopkins Medicine, Baltimore, USA

I was asked to talk this year about triple negative breast cancer in the metastatic setting as a chronic disease, which was quite a challenging topic. During the same session we talked about oestrogen receptor positive breast cancer and HER2 positive breast cancer as chronic disease and those are two subtypes where we have targeted therapy so it’s a little bit easier to think of those subtypes as chronic illnesses. In triple negative breast cancer we’ve not been as fortunate, today really chemotherapy drugs are the only treatment available for women with triple negative breast cancer. So during my talk I explained to the audience that I personally believe that triple negative breast cancer includes many subtypes. Those are about 20% of breast cancer but within those 20% there may be seven or more sub-subtypes and if we know what are the pathways and targets within those subtypes we will be able to come up with new targeted therapies.

I also gave examples from some small experiences where a handful of patients were able to stay on the treatment on the study for many months to over a year, so I do believe that there are some patients with triple negative breast cancer than can be treated for a prolonged period of time and, again, we need to know more about the tumour and the mechanism of drugs that may achieve long-term outcomes.

What work is underway to research these sub-types?

I think the challenge for the next few years is how to clinically use assays that will tell us up front when we sit with the patient at clinic what her tumour really looks like, not just by oestrogen, progesterone, HER2 receptors but a more complicated pathway analysis. There are several experiences already in the literature from laboratories when we do know of some potential targets and some of those targets already have drugs that can be used that are in the clinic. For example, perhaps about a third of the triple negative breast cancer will have deficiencies in DNA repair. This is very common in cancers in BRCA mutation carriers but there are some sporadic or non-genetic breast cancers that are triple negative in which we see those DNA repair deficiencies. In those cancers we may see benefit to treatment such as carboplatin, cisplatin and PARP inhibitors.

So, as I stated a little bit earlier, right now the mainstay of treatment is chemotherapy based and we can tell a patient who sits in front of us in the clinic who has metastatic breast cancer that’s triple negative that we accept that whatever cytotoxic medication we’re going to use will work for a period of time but that will quit working. So I encourage strongly those patients to look into clinical trials and see what else may be available to them. Many clinical trials include a cytotoxic plus a targeted therapy and I think those hold promise; I would definitely encourage patients to look at their immediate area to see what might be available to them.