It’s becoming increasingly clear that the old saying “one size fits all” doesn’t work when it comes to cancer treatment. The more scientists discover about the genetic faults that underpin different tumours, the more it’s possible to divide them into sub-types, which may in turn respond very differently to treatment. A good example of this is the breast cancer drug Herceptin, which only works for patients whose tumours have high levels of a molecule called HER2.
Now scientists in Edinburgh funded by Cancer Research UK have made an important discovery which could help to improve tailored treatment for breast cancer. They’ve found that a genetic test that’s already used in breast cancer patients can predict whether an individual will benefit from certain drugs or not. And we could see it become standard clinical practice within a couple of years.
The drugs in question are anthracyclines, including one called epirubicin. Epirubicin as an effective drug for breast cancer, but it only works in a certain proportion of patients. But because it can cause quite bad side effects, and it doesn’t work for all patients who get it, its use in the clinic has been limited.
So Professor John Bartlett and his team looked at tumour samples from more than 2,500 women who were on clinical trials of epirubicin, to find out if they could identify genetic markers in their cancers that would predict whether they did or didn’t respond to the treatment.
In the end, they found that women who had extra copies of chromosome 17 were likely to respond to the treatment. But women with the normal number - that’s two copies – were less likely to respond.
And here’s where it gets interesting. This extra dosage of chromosome 17 is already known to be involved in breast cancer, because this is the region of the genome that harbour HER2. So there’s already an effective test to look for duplications of the chromosome, which is routinely used by doctors to find out if a woman will benefit from Herceptin treatment.
The team are still waiting for the results of one final clinical trial to confirm the accuracy of the test. But if all goes well, we should see this becoming clinical practice within a year or two.