A New $500 Blood Test Could Detect Cancer Before Symptoms Develop

An international team of researchers have developed a new test that screens for multiple types of cancer using only a blood sample.

The research published today in Science and led by scientists at Johns Hopkins School of Medicine in Baltimore describes a new test called CancerSEEK, which simultaneously looks for the presence of eight different types of cancer, including lung, breast and colorectal cancers, which are together responsible for more than 60 percent of cancer deaths in the U.S.

The researchers took blood samples from 1,005 people with one of the eight different cancer types, finding that CancerSEEK was able to reliably identify the tumors in 70% cases. The success rates ranged from an impressive 98% in people with ovarian tumors to only 33% in people with breast tumors.

However, the researchers are positive about the potential impact of the test. “If we are going to make progress in early cancer detection, we have to begin looking at it in a more realistic way, recognizing that no test will detect all cancers,” said Bert Vogelstein, M.D., Professor of Oncology at Johns Hopkins School of Medicine.

The scientists also used CancerSEEK on 812 healthy people with no history of cancer to make sure the test only picked up genuine cancers. Only seven of the 812 healthy people tested were flagged as positive using CancerSEEK, with the researchers noting that they couldn’t be certain whether these seven individuals were true false positives or indeed had early-stage cancer with no symptoms.

The rate of false positives reported here is far lower than with conventional screening tests for specific cancers, such as mammography with a 10% false positive rate and colon cancer screening with variable rates of false-positives depending on the test used. Additionally, the proposed cost of CancerSEEK is $500, less than most currently available screens for single cancer types, making it an appealing prospect for individuals and insurers alike.

Blood-based “liquid biopsy” tests have been hit with recent controversies about their ability to accurately detect cancer mutations. Combined with their several-thousand-dollar price tag, it is safe to say that the jury is still out as to whether they will justify their early hype and become routine tools for diagnosing and helping guide treatment for cancer patients.
Most liquid biopsies survey a large number of genes in an attempt to identify therapeutic targets for drugs, but CancerSEEK takes a different approach and focuses on early diagnosis, looking at mutations in just 16 cancer-associated genes and the levels of eight protein biomarkers. The data from these two parameters are then combined with an algorithm to “score” each blood test and ensure that the results are accurate and reliable.

Early-cancer detection tests do exist for some cancers and are very effective in diagnosing cancer early, such as mammograms for breast cancer and cervical pap smears for cervical cancer. The only widely-used blood-based test is a controversial test for prostate cancer looking at just a single protein biomarker, prostate specific antigen (PSA). Remarkably, despite having been around for 25 years, scientists have been unable to reach a consensus as to whether the PSA test is actually useful or not, so there is undoubtedly great room for improvement with blood-based cancer screens. Importantly, for five of the eight cancers tested for by CancerSEEK, there are no early screening tests currently available.
Even the most detailed scans can only pick up tumors when they reach a certain size. Currently available liquid biopsy tests give no indication as to where a tumor might be, with many cancer mutations found in a variety of tumor types. Remarkably, using only blood, in 63% of patients CancerSEEK was able to specify the organ where the cancer was, giving oncologists vital clues as to where to do further scans in order to pinpoint the location of the tumor and prescribe effective treatment. In 83% of people, the test was able to narrow the location down to two anatomical locations.

Many adult cancers grow very slowly, taking 20 to 30 years to progress to full-blown, symptomatic cancers. By the time they are diagnosed these cancers have often spread, making them incredibly difficult to treat. Cancers that have not spread past the original tissue they started in can often be cured by surgery alone, sparing a patient from the considerable potential side effects that often accompany chemotherapy and radiotherapy treatments.

Joshua Cohen, the lead author of the study, said, “our ultimate vision is that a person goes to their primary care provider for a routine checkup and at the same time as testing their cholesterol, they have a screening to test for different types of cancer.”
The researchers stress that a larger-scale trial must be done before CancerSEEK can be made commercially available, and they are embarking on a new study featuring 10,000 healthy individuals, which they hope will allow them to further evaluate if the test is able to accurately predict who ultimately develops cancer.

“The prospective study will answer the question, can this test detect cancer earlier than conventional methods, and at the same time as this, we will be working on improving and refining CancerSEEK,” said Cohen.

However, CancerSEEK is not quite the lone ranger in developing blood-based tests for cancer diagnosis. GRAIL, a spin-out company of Illumina created waves this time last year after an ambitious proposal to study the effectiveness of their early-diagnosis test, also via the recruitment of 10,000 individuals, this time with and without cancer. With an impressive list of investors, including Bristol-Myers Squibb, Celgene, Merck and Amazon and a scientific advisory board with substantial credentials, GRAIL seems to be in a very strong position. Notably however, GRAIL only tests for tumor DNA, not the additional protein biomarkers that CancerSEEK includes, so it remains to be seen how the two compete on vital elements such as ability to detect various cancer types and avoiding false-positives.

Currently, screening for specific cancer types is only recommended for at-risk people, whether it be due to a family history of cancer, underlying genetic conditions predisposing to cancer or just older age. However, the affordability and reliability of CancerSEEK raises the genuine possibility that cancer screening could become as mainstream as a cholesterol test.

Photographer: Daniel Acker/Bloomberg

About Felix Brambaifa 322 Articles
Felix Brambaifa is a writer and blogger from Nigeria. The founder of Naturally Healthy People and other niche blogs.

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