Implementation of genetic testing in breast cancer patients
Dr Nadine Tung - Beth Israel Deaconess Medical Center, Boston, USA
It’s extremely important to offer germline BRCA testing and germline genetic testing to appropriate breast cancer patients. So the question becomes who are the appropriate breast cancer patients? In the United States we use the NCCN guidelines which are extremely sensitive, very, very broad. It’s a long list of breast cancer patients who should be offered testing: any patient diagnosed aged 45 and younger; anyone with personal and family history of a number of criteria like ovarian cancer and pancreas cancer and male breast cancer. So it’s a long list and the sensitivity is quite high.
Recently the American Society of Breast Surgeons has endorsed offering germline BRCA testing and germline genetic testing also for PALB2 to all breast cancer patients. So this has raised a controversy as to whether we should be doing this in all breast cancer patients. There are a couple of studies that have tried to look at this and the best one by Biche [?] and colleagues shows that if we follow the NCCN criteria what would we be missing. We’re really missing less than 1% of the breast cancer patients who would have a BRCA mutation or a PALB2 mutation, any high risk mutation. So it’s very, very uncommon to miss a patient with a high risk breast cancer mutation.
There are about 3% we’d miss with mutations in the more moderate risk breast cancer genes like ATM and CHK2 and NBN. The utility of finding those mutations and whether they affect the management of our breast cancer patients is really less clear. So if we’re sticking to NCCN we’re doing pretty well.
One of the problems with testing all breast cancer patients is certainly the cost and also the accessibility of genetic counsellors and experts who can handle both those found to have a mutation but those found to have a variant with unknown significance which can create a lot of anxiety and questions. So if we’re going to continuously broaden who is going to get genetic testing and ultimately test all breast cancer patients we need a different genetic testing service model that would be able to handle such large population type testing.
One important point to note is that if studies show that PARP inhibitors have efficacy in our BRCA carriers with early stage breast cancer, for example if the OlympiA trial is positive, then it really may be necessary to offer genetic testing to all of our breast cancer patients in order not to miss the BRCA carriers which would be consistent with our policy in the metastatic setting.