Careful readers of this blog will have noted that along with reporting about the change in reimbursement for cancer drugs (and to get the real scoop on that you should see JD Klienke’s excellent article in Health Affairs), there’s also been a trend generally in favor of chemo-sensitivity testing before chemotherapy–largely considered a fringe activity by mainstream oncologists. Then this week the NEJM had an article generally in favor of pre-chemo testing. Did the appearance of this article mean that oncologists were moving the way of the pre-chemo testing radicals or did I as the dumb layman misunderstand it? I asked Dr Harvey Frey, who has written for laymen on this subject for THCB before but has generally not been in favor of it, what he thought.
I think you’ve got it right.
Now oncologists guess at prognosis and probable effective treatment based on how a cancer looks under the microscope, how extensive it is when found, and some blood tests. But even within the groups they’ve determined that way, there are still huge variations in actual patient response and survival rates. Since they never know who needs the treatments for sure, many patients are treated who might not need the treatment, and some get ineffective treatments before finding an effective one, and since the treatments are not innocuous, that’s bad.
They first tried doing sensitivity testing by growing cancer cells with different chemotherapeutic agents. For a variety of reasons, that never was very helpful. For years they have thought that, if only they could determine the actual genes responsible for cancer, they could break down the large heterogeneous groups into smaller groups with better defined responses, and spare many patients any treatment at all.
This study is a start toward that end, but still a small step. The technique doesn’t require that they try to grow the cells, but can be done on regular biopsies as obtained now. But so far all it’s shown is a correlation between their test and survival. They haven’t yet shown that they can predict response to hormones or chemotherapy. But there’s every reason to hope that they will ultimately be able to make such predictions, at least with better accuracy than we can now.