Cancer: A blood test may detect cancer at early stages

A non-invasive blood test, which could be used as a potential tool for the early detection of five common types of cancer up to four years before conventional diagnosis, is reported in a study published in Nature Communications.

The survival of cancer patients significantly increases when the disease is identified at early stages, as the tumour can be surgically removed or treated with appropriate drugs. However, only a limited number of screening tests exist for a few cancer types.

In their study, Kun Zhang and colleagues describe a blood-based cancer screening test, called PanSeer, which examines cancer-specific methylation signatures in the blood. The authors perform an analysis on plasma samples obtained from 605 asymptomatic individuals, 191 of whom were later diagnosed with cancer. They also profile plasma samples from an additional 223 diagnosed cancer patients as well as 200 primary tumour and normal tissue samples. The authors demonstrate that their test can potentially detect with high specificity five common types of cancer (stomach, esophageal, colorectal, lung or liver cancer) in post-diagnosis patients, as well as in asymptomatic individuals up to four years before conventional diagnosis.

The authors emphasize that the PanSeer assay is unlikely to be predicting patients who will later go on to develop cancer. Instead, it is most likely identifying patients who already have cancerous growths, but remain asymptomatic to current detection methods. They conclude that further large-scale longitudinal studies are needed to confirm the potential of the test for the early detection of cancer in pre-diagnosis individuals.