Research suggests that a blood test could diagnose cancer years before signs of the disease emerge.
Early detection maximizes the patient’s hopes of survival, but symptoms can often be mild, vague, or even non-existent.
To help detect more cases, scientists at Fudan University in Shanghai collected blood samples from hundreds of apparently healthy people.
By detecting tumor “signatures” in the bloodstream, the test detected five types of cancer in 95% of the participants who developed the disease without any symptoms until four years later.
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While more study is required, scientists hope that the blood test, called the PanSeer, will one day be a “first-line test,” such as smears or mammograms.
One in two people born after 1960 in the UK will statistically develop cancer in their lifetime.
In the United States, one in two men and one in three women alive are expected to be diagnosed.
Early detection of the disease may allow doctors to surgically remove it or prescribe relatively minor medications, while treatment options may be limited or more severe as it progresses.
National cancer screening programs are restricted to cervical smears, mammograms, and colonoscopies.
To help detect the disease early, Fudan scientists observed participants in the Taizhou Longitudinal Study, who provided blood samples for long-term storage.
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PanSeer looked for any “methylation of circulating tumor DNA,” which has previously been shown to be a “promising cancer biomarker.”
Methylation occurs when a substance called a “methyl group” is added to another molecule.
When this occurs within tumor suppressor genes, they can be “silenced”, triggering uncontrolled malignant growth.
Of 605 asymptomatic participants, 191 were diagnosed with cancer of the stomach, esophagus, colorectal, lung, or liver four years later. Additional analysis was also performed on 223 cancer patients.
The results, published in the journal Nature Communications, revealed that PanSeer detected five common types of cancer in 88% of patients after diagnosis.
It was detected correctly in non-cancerous cases 96% of the time.
PanSeer also detected the disease in 95% of asymptomatic participants who were later diagnosed, although the scientists emphasized that further studies are required to confirm this.
However, they believe their results “demonstrate that cancer can be detected non-invasively up to four years before the current standard of care.”
“What we show is: up to four years before these people enter the hospital, there are already signatures in their blood that show they have cancer,” said study author Professor Kun Zhang of the University of California, San Diego, according to The Jerusalem Post. “That has never been done before.”
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Unlike other attempts to create a test through methylation, PanSeer only requires a small tube of blood.
It also has the potential to detect disease “regardless of tissue of origin.”
“So we envision a clinical context in which PanSeer could be used as a front-line display,” the scientists wrote.
“Any patient who tests positive for PanSeer will undergo a more expensive reflex blood test and / or follow-up imaging to allow mapping of the tissue of origin.”
Scans or biopsies could confirm the disease, they added.
