Prof William Gallagher, director of the first Irish Cancer Society Collaborative Cancer Research Centre, Breast-Predict, said approximately two thirds of women with early-stage breast cancer who are given chemotherapy do not need it but the existing test, Oncotype DX, is not precise enough to identify them definitively.
“We have a problem with over-treatment of early stage breast cancer. Two thirds of women given chemotherapy don’t need it, but they are given it to catch the one third that do. So we are giving sometimes toxic therapy to women who don’t need it,” said Prof Gallagher.
The Oncotype DX assay (a diagnostic test) stratifies women into high, moderate or low risk of the cancer returning.
“So if you’re low risk, that’s fine, we would suggest that you don’t need chemo. But at the moment, we don’t know what to do with the intermediate [medium risk] group,” said Prof Gallagher.
As a result, those identified as moderate risk were also being sent for chemotherapy which they did not necessarily need. The OncoMasTR test currently being developed aims to divide the women into just two groups, high or low, with the hope that this will reduce the numbers sent forward for chemotherapy.
“So we have very promising early clinical data on a couple of hundred breast cancers, and the idea is we now need to develop this as a test which can be used on patients, so we have a two-year programme to develop that,” he said.
“Our ultimate aim is to eliminate chemotherapy for as many women as possible, because obviously you have the side-effects associated with chemotherapy for patients who don’t really require it.
“Also chemotherapy itself carries an inherent risk. A smallish number of patients, one in every 200, could potentially die from chemotherapy, and it’s only moderately effective anyway, it only has a certain degree of benefit.”
Doctors knew from historical data that at least two thirds of women with early stage invasive breast cancer do not require chemotherapy because they have an inherent low risk of the disease coming back or spreading after the tumour is removed.
“So the whole idea with the test we are developing is that you can actually identify upfront who is going to have a low risk of recurrence or a high risk,” he said.
Clinical validation work for the new test is being done in conjunction with investigators within the Breast- Predict Centre, while a spin-out company OncoMark (www.oncomark.com), is working towards making sure it meets the essential requirements for the market.
Prof Gallagher, co-founder and chief scientific officer with OncoMark, hopes the test will get CE marking within two years. a legal requirement to place a device on the market in the EU.
“We would hope to have that test CE marked and then we would be able to — if we have suitable clinical validation and data is supported — go on to use that test in a hospital setting.”