Can a Blood Test Tell You If You Have Cancer? Not Yet – But Maybe Someday

Healthy Living

February 19, 2018

Could you, one day, take a simple blood test to learn if you have cancer? U.S. National Institutes of Health (NIH) director Dr. Francis Collins wrote in January 2018 about new research into the so-called “liquid biopsy.” Although much more research and development are still needed, this procedure screens a blood sample for particular proteins that are given off by cancerous tumors.

Known as CancerSEEK, the procedure was part of a study funded in part by the NIH. Research was performed at Johns Hopkins University in Baltimore, Maryland.

The procedure detects proteins and fragments of 16 specific genes. It can be used to scan blood samples for eight different types of cancers. These include some of the deadliest cancer types, such as liver, ovarian and pancreatic cancer. NIH researchers included 1,005 cancer patients in the study, and their cancers were detected by CancerSEEK accurately 70 percent of the time. This is a relatively high percentage compared to other cancer detection studies.

NIH researchers also tested a group of 812 volunteers who were not known to have cancer. Among the group of healthy volunteers, CancerSEEK gave false positives less than one percent of the time. However, it is not known at this time whether patients with inflammatory diseases like arthritis might have higher false-positive rates if tested.

Early detection leads to more successful treatments

Cancers start out as normal bodily cells, but then mutate and reproduce uncontrollably. As these cells grow out of control, some of them die in the process. Proteins and genetic markers from dead cancer cells are filtered out of the body through the bloodstream. These are the substances that CancerSEEK detects in a blood sample.

One of the best tools in medicine’s arsenal for successful cancer treatment is early detection. Cancers that are identified before large tumors have the chance to form and spread throughout the body are most likely to be found, treated and removed. Researchers hope that “liquid biopsy” techniques will allow for more cancers to be detected in the early stages before a patient even has any symptoms. In the NIH trial, CancerSEEK was best at detecting stage two and stage three cancers. The procedure detected stage one cancers about 43 percent of the time.

Not all cancers can be detected in the bloodstream. Some don’t release detectable levels of identifying substances in the bloodstream. Further, being able to detect the presence of cancerous cells in the blood doesn’t always tell doctors where in the body the cancer may be located.

CancerSEEK does have a mechanism for pointing the medical team to the organ in which the cancer most likely originates. Using machine learning, the procedure can narrow down the cancer source to one or two organs in about 83 percent of patients with positive results. Further testing is then needed to determine which treatments will be most appropriate.

Treating cancer in the future

In the future, liquid biopsy procedures like CancerSEEK will need to have accuracy rates of higher than 70 percent to be used successfully in patients. The procedure may also need to get better at detecting specific types of cancers, including breast, colorectal and lung cancers.

Still, there are reasons to be optimistic for the future of blood-based cancer testing. Liquid biopsy blood draws can be performed in a wide variety of healthcare settings, from a general practitioner’s office to a community health clinic. Since the technology is relatively inexpensive at less than $500 per test, CancerSEEK procedures may allow for access to early detection for a greater share of the public as well. Blood testing would certainly be less expensive than diagnostic imagery or exploratory surgery and without the same side effects.

CancerSEEK also gives oncologists a tool for screening people at average risk for certain cancers that don’t currently have a go-to screening tool for this population. These include cancers of the esophagus, ovaries, liver, pancreas and stomach, according to the National Center for Biotechnology Information.

Researchers will have to balance the potential positives of increased early detection for a wider population against the risk of overtreatment. Aggressively treating cancers in patients who may never have developed tumors large enough to require such treatment hazards unnecessary risk and expense.

The NIH plans to continue testing CancerSEEK. It has begun enrolling 10,000 healthy volunteers in a large-scale trial of the procedure. The private Marcus Foundation plans a five-year study including more than 50,000 healthy female volunteers.