New blood test may be able to detect 18 cancers in early stages

In the study, researchers collected blood plasma samples from 440 people diagnosed with 18 different types of cancer, prior to their receiving treatment for the diseases. Plasma samples also were collected from 44 blood donors who did not have a cancer diagnosis.

The plasma samples were initially measured for more than 3,000 proteins known to be associated with cancer. From these, a panel of 10 sex-specific protein biomarkers was established.

Researchers noted that, individually, these proteins were only moderately accurate at detecting early stage cancers. However, accuracy increased dramatically when the biomarkers were analyzed collectively.

The blood tests detected stage 1, 2, and 3 cancers, Afshin and colleagues said, but were especially effective at detecting early stage cancers.

The ability to identify low levels of cancer biomarkers before tumors have had any significant systemic impact on the body could be a major boost to cancer treatment, the study authors noted.

“A sex-specific test that can detect cancer at an earlier stage would get patients onto treatment before the cancer has had a chance to spread and when there are generally more treatment options,” said Karimi.

“A person’s gender can influence their molecular susceptibility for getting cancer,” he added. “And sex hormones also affect the development of various cancers. More men get cancer than women and men have higher mortality rates than women for most cancers, including bladder, kidney, colorectal, liver, esophagus, head and neck, brain, skin and blood.”

Using biomarkers in the blood to detect cancer is not new.

For example, a blood test has been developed that uses genetic biomarkers to detect more than 50 types of cancer.

However, these tests are not significantly accurate at detecting early stage cancers and remain too expensive to be used for routine screening, according to Afshin and his colleagues.

“A simple, inexpensive blood test that could identify the existence of early-stage cancers in patients would definitely improve upon current screening tools, particularly in younger patients for whom cancer may be an uncommon but not entirely infrequent occurrence and for whom screening protocols are not applied because of the poor predictive value,” Dr. Mary E. Edgerton, a professor in the Department of Pathology, Microbiology, and Immunology at the University of Nebraska Medical Center who was not involved in the study, told Medical News Today. “Such testing could also replace expensive screening by imaging, reduce radiation exposure due to image-based screening, and potentially eliminate invasive screening procedures (e.g., colonoscopy).”

However, she said, “this exciting step forward could only be achieved if the tests are proven to be sensitive and specific in the larger population… For less common cancers, or age groups with less prevalence, this requires very high specificity and sensitivity to overcome the problems of false discoveries overwhelming the number of people with actual disease. A screening test without sufficient positive predictive value could lead to unnecessary and possibly invasive tests in patients that would decrease its value.”

The most common of existing protein-based blood tests identifies prostate specific antigen for prostate cancer screening. Others are used to guide breast, ovarian, and colorectal cancer treatment.

Biomarkers can also be used to diagnose several individual types of cancer, such as cancers of the liver and lungs.

However, the study noted, nearly 60% of cancer-related deaths are due to cancers for which no screening tests currently exist.

“These [tests] will ultimately serve a similar benefit as current [ones] that contain DNA, RNA, and proteins to identify not only individuals with cancer, but those that may have increased risk,” Dr. Richard Reitherman, a radiologist and medical director of breast imaging at the Orange Coast Medical Center’s MemorialCareBreast Center in California who was not involved in the study, told Medical News Today. “This ultimately may be at a time when the cancer is not detectible by any other means.”

“Additional cancer diagnostic and screening tools need to be developed that are accessible and available to patients. Researchers are making progress in this area – blood tests have been developed that screen for some cancers, but they are not accessible to everyone,” said Karimi, who noted that City of Hope has developed a blood test that can be used to detect early-onset colorectal cancer.

“If such a test were to be validated in a larger population and the detection kits developed as an inexpensive option… this would be a giant step forward in cancer screening,” said Edgerton. “It could hypothetically become part of a yearly physical examination.”

However, she cautioned that the small size of the current study and the continued possibility of false positive results mean “this publication is far from demonstrating that this concept has achieved realization now.”

In addition to blood testing, individuals also can get genetic tests for known hereditary risk factors for particular types of cancer.

“Knowing if you carry genes for a particular kind of cancer can ensure you are screened often and receive timely and appropriate treatment,” said Karimi.