John Witte, PhD, in his lab with graduate student Clint Cario. Photo by Elisabeth Fall
What if screening for cancer was as easy as checking your cholesterol? That’s the promise of techniques currently in development that may one day make it possible to detect the earliest stages of cancer with an annual blood draw.
So-called "liquid biopsies" involve extracting free-floating cancer cells or cancer DNA from the bloodstream (or in some cases from the urine) to get information about tumors too small or hidden to detect with standard techniques. This could make it possible for clinicians to remotely monitor how cancer patients are responding to treatment, to detect early warning signs of recurrence, and even to pick up the very first signs of cancer in otherwise healthy people.
Over the past year, industry excitement surrounding these techniques has accelerated rapidly, with established biotech companies such as Qiagen, Roche and Illumina and a bevy of startups such as Guardant Health and Foundation Medicine competing to commercialize liquid biopsy and bring it to patients within the next few years.
While many researchers agree the technology is exciting, the question is: Will liquid biopsies become the next big thing in cancer diagnostics, or will it simply have niche applications?
"Right now it’s the Wild West," said John Witte, PhD, who co-directs the cancer genetics program in the UCSF Helen Diller Family Comprehensive Cancer Center and is working to improve the sensitivity of liquid biopsy techniques to help track the development and progression of potentially deadly prostate cancers.
"There are a lot of different ways liquid biopsies might be transformative for cancer screening and monitoring, but we’re not yet sure how well the techniques will work. Still, the potential value is enormous and well worth risky ventures."
There are a lot of different ways liquid biopsies might be transformative for cancer screening and monitoring, but we’re not yet sure how well the techniques will work.
How Does Liquid Biopsy Work?
Currently physicians remove tumor samples surgically or with biopsy needles, then examine the tissue under microscopes or analyze it genetically to make a diagnosis and guide treatment. This approach is expensive, invasive and usually only possible once a tumor has grown large enough to already be a major threat. Worse, cancers often continue to mutate as they spread, meaning that a biopsy of the original tumor may not help to treat invasive metastatic colonies.