This story describes a potential advance in precision medicine. Certain cancer therapeutics target tumors that have specific characteristics, such as the so-called PARP inhibitors. A diagnostic test to see if those specific characteristic exist, such as the liquid biopsy test described here, could help select patients most likely to benefit.
Unfortunately, this article is essentially a rewrite of the news release, glossing over the measured benefits, the costs, the harms–and much more.
There are many details of this study that warrant critical examination. Readers won’t be well-served by this story that parrots the PR promotions.
The article did not mention costs.
The story did not quantify the benefits of using the three-in-one liquid biopsy. Readers learned that results of the biopsy were used to initiate (or not) and continue (or not) treatment with a cancer therapeutic drug that targets certain types of prostate cancers in men. Readers did not learn anything about the trial design or how effectiveness of the biopsy was measured. At the very least, it would have been helpful to know what proportion of patients “benefited” (changing drug vs. initiating drug).
The story made no mention of potential harms of the liquid biopsy itself or of guiding chemotherapeutic treatment decisions based on results of the liquid biopsy.
What about false positives? And false negatives? Erroneous results from a “simple” blood test could lead to a patient stopping the drug prematurely or initiating erroneously. Stories about screening tests must include the false positive and false negative rates for these reasons–they are a real risk.
The story does discuss the various ways the liquid biopsy might be helpful. Its descriptor — three-in-one — was explained for readers; its essentially a way to select patients that might benefit from targeted cancer therapy and to monitor response and resistance to the chemotherapeutic drug. But no study results were outlined, other than a brief mention that this was a phase 2 trial with about 49 men in the study.
The article did not overhype the risks of prostate cancer.
The story quotes two sources: 1) the first author, who’s a researcher at the UK’s Institute of Cancer Research; and 2) the Chief Executive of the very same research institution. No outside sources were mentioned, much less quoted. It was good that funding sources were mentioned, however.
The article makes no mention about alternatives. It doesn’t make clear what current standard therapy is for prostate cancer or how patients are currently selected for treatment with the targeted cancer drug.
It also didn’t discuss that the drug itself–olaparib–is still being researched for effectiveness.
The story does not help readers understand whether this blood test is available now–or if not, when it might become available for wider, non-research use.
The article makes clear that this is a new test for circulating DNA that provides specific information about a cancer patient’s individualized cancer profile. However, the only people to say so are the researchers testing the liquid biopsy. This claim would carry more weight if it came from an independent source.
It appears that the story heavily relied on this news release from the UK’s Institute of Cancer Research. And without attribution. For example, this quote that appears in the news release appears verbatim in the news story:
“Our study identifies, for the first time, genetic changes that allow prostate cancer cells to become resistant to the precision medicine olaparib.
“From these findings, we were able to develop a powerful, three-in-one test that could in future be used to help doctors select treatment, check whether it is working and monitor the cancer in the longer term. We think it could be used to make clinical decisions about whether a PARP inhibitor is working within as little as four to eight weeks of starting therapy.
“Not only could the test have a major impact on treatment of prostate cancer, but it could also be adapted to open up the possibility of precision medicine to patients with other types of cancer as well.”