Scientists have developed a blood test that is believed to provide a sensitive and low-cost approach to early detection of cancer in people with neurofibromatosis type 1 (NF1).

Researchers from the National Cancer Institute (NCI), a part of the National Institutes of Health (NIH), and Washington University School of Medicine developed the test.

People with NF1 usually develop benign tumours along nerves, dubbed plexiform neurofibromas (PN) which can turn into aggressive forms of cancer.

The new test is said to provide an effective approach to determine whether the non-cancerous tumours are transformed into a precancerous condition.

Also, the blood test is designed to help doctors monitor how the patients are responding to treatment for their cancer.

Physicians use either MRI or PET imaging scans or biopsies to check whether PNs have turned into aggressive form, called malignant peripheral nerve sheath tumours (MPNST).

MPNSTs are often linked to poor prognosis as cancer spreads rapidly, but becomes resistant to both chemotherapy and radiation.

The team led by researchers from Washington University School of Medicine has collected blood samples from 23 people with PNs, 14 with untreated MPNST, and 16 healthy people.

From the blood samples, scientists identified cell-free DNA shed from cells and studied differences in the genetic material among three groups using whole-genome sequencing.

In the study, cell-free DNA in patients with MPNST showed various features that distinguished it from the DNA in the other two groups.

Samples from MPNST patients had shorter pieces of cell-free DNA than those in people with PNs or without NF1.

Also, the proportion of cell-free DNA that comes from tumours, dubbed plasma tumour fraction was much higher in people with MPNST compared to those with PN.

The differences allowed researchers to differentiate between patients with plexiform neurofibromas and those with MPNST, with an accuracy of 86%.

Blood tests of this kind are anticipated to facilitate the early detection and monitoring of patients with other cancer-predisposing genetic disorders.

The study was supported by the Intramural Research Program of NCI and the National Institute of General Medical Sciences, a part of NIH.

Study co-author Jack F Shern said: “The doctors are going to be watching for cancerous tumours, and you’re going to be watching for them, but you really want to discover that transformation to cancer as early as possible.”

“What we don’t have right now is a tool to help us determine if within that big, bulky benign plexiform neurofibroma, something bad is cooking and it’s turning into an MPNST.

“So we thought, ‘What if we developed a simple blood test where instead of a full-body MRI or a fancy PET scan, we could just draw a tube of blood and say whether or not the patient has an MPNST somewhere?’”