Within the current body of liquid biopsy research, most studies seem to have focused on blood testing. There have been developments in creating blood tests to detect early stages of colorectal cancer and breast cancer, among others.
Still, this evolving research has some limitations. In general, cancer-screening tests can come with the risks of providing false positive or false negative results, overdiagnosis or even unnecessary treatments, all limitations to which blood tests could fall victim.
Overtreatment also can be a risk if a test detects a cancer that turns out to be slow-growing and therefore possibly harmless.
For instance, 1 in 3 women with breast cancer detected by a mammogram may be treated unnecessarily, because their screening tests found tumors that are slow-growing, according to a study published in the Annals of Internal Medicine in 2017.
On the other hand, finding cancer in an easy-to-collect blood test could improve survival rates when cancer is detected early and could be favorable among patients.
Being able to detect cancer from a simple blood draw compared with more invasive biopsies has been called the “holy grail,” not only for physicians but also for patients, said Medha Deoras-Sutliff, a two-time breast cancer survivor and executive director of The EHE Foundation, a nonprofit that focuses on a rare type of vascular tumor called epithelioid hemangioendothelioma.
Sutliff was first diagnosed with breast cancer 26 years ago, at the age of 27, after she told her primary care physician about a lump in her breast. She underwent a needle biopsy, during which a needle was forced into her breast at the site of the lump in order to pull out samples of it.
“Within a few minutes, they were able to look at it, and I got an answer it was benign,” said Sutliff, a graduate of the AACR Scientist-Survivor program.
“I thought that was OK, but we talked to a few other medical providers, and they thought, ‘Well, you can also get it removed, and you don’t have to think about it again,’ ” she said.
“I did remove it, and on examination after my surgery, they found, in another area of that lump, some suspicious cells. So that to me is how with biopsies, traditional biopsies, they pull sections from a certain area, and that’s it. But does that mean that the whole area of suspicion is uniform?
Well, we know that’s not true,” she said. “Cancer is not the same in each patient and even within each tumor. A biopsy only looks at one specific area of a suspected tumor.”
Sutliff continued to monitor her breasts, and when she was 36, physicians noticed something suspicious on her mammogram.
This time, “I had to do a core needle biopsy,” she said. “You lay flat on a table, and you’re on your stomach, and your breast is placed in a hole, and your table is raised.
The radiologist is under you, and you’re given a local anesthetic, and a hollow needle is guided into the breast.”
Her biopsy showed that she had breast cancer again, but it was in its early stages, and after treatment, Sutliff quickly recovered. However, the biopsies for both of her cancer diagnoses were “difficult,” she said.
If the future holds a simple blood test that could take the place of more invasive biopsies for some patients, that would be beneficial, Sutliff said.
“That holy grail is that blood draw will detect cancer in your blood, be able to determine where exactly that cancer may be in the body and hopefully tell us whether that cancer requires treatment,” she said.