Researchers from the National Cancer Institute’s (NCI) Center for Cancer Research and Washington University School of Medicine have collaborated to develop a blood test that may facilitate early detection of cancer in patients with neurofibromatosis type 1, a genetic disorder. The test is also anticipated to help monitor response to treatment.

Blood samples were collected from 23 patients with plexiform neurofibromas, 14 patients with untreated malignant peripheral nerve sheath tumors (MPNST) and 16 healthy persons who did not have neurofibromatosis type 1. The majority of the study participants were adolescents and young adults.

Plasma cell-free DNA was isolated from the blood samples, which was examined using ultra-low-pass whole genome sequencing technology to find out differences between the three groups. Length of fragments of cell-free DNA in patients with MPNST was found to be shorter than those in people with plexiform neurofibromas or without NF1. The proportion of the plasma tumor fraction was much higher in people with MPNST in comparison to those with plexiform neurofibromas. These features could distinguish between patients with plexiform neurofibromas and those with MPNST with 86% pretreatment accuracy.

The plasma tumor fraction could also be used to monitor response to treatment. Increase in the plasma tumor fraction was indicative of metastatic recurrence, whereas a decrease in plasma tumor fraction following treatment was associated with a reduction in the size and number of tumors. These results are published in the journal PLoS Medicine.

MPSNT is an aggressive cancer and is the major cause of mortality in these patients. It develops in the benign plexiform neurofibromas. Biopsy or MRI/PET scans currently used to detect the malignant transformation may not always be reliable. A blood test to screen high risk patients for early detection of malignant change, therefore could prove to be very useful, particularly in resource-limited countries.

(Source: National Institutes of Health (NIH) Press Release, August 31, 2021)