Study: PET helps distinguish neurofibroma from sarcoma

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FDG-PET is a highly accurate way to distinguish between neurofibromas and sarcoma, according to a study from UCLA’s Jonsson Comprehensive Cancer Center that was published online this week in the Proceedings of the National Academy of Sciences.

In the study, UCLA researchers showed that the loss or decreased expression of the tumor suppressor gene PTEN is essential for neurofibromas to turn into a malignant type of sarcoma. The investigators had developed a mouse model of neurofibromamatosis type 1 (NF1) that illustrated the importance of PTEN tumor suppressor in this malignant transformation, a finding validated in malignant peripheral nerve sheath tumors (MPNST).

FDG-PET scans—in both mice and humans—helped researchers to accurately distinguish between the benign and malignant tumors, the authors said.

“The loss of expression of PTEN in the human sarcomas we studied mirrored the loss of PTEN in mice, and we anticipate being able to target this pathway abnormality for the development of new methods of diagnosis and treatment” said Fritz Eilber, MD, director of the UCLA sarcoma program and an assistant professor of surgical oncology. “Within the sarcoma world, malignant peripheral nerve sheath tumors are one of the most lethal sub-types, so this is a significant finding and may lead to new and more effective treatments.”

NF1 is among the most common genetically-inherited disorders, according to the study's senior author Hong Wu, MD. Patients with NF1, Wu said, have a 10 percent lifetime risk of developing MPNST.

According to the authors, there are no effective treatments to prevent these benign NF1 tumors from turning into malignant tumors. The genetically engineered mouse model will be used to screen drugs that may be able to block signals that instruct the cells to change from a benign state to a malignant one, providing treatment options for patients with the deadly form of cancer.

“I think these findings will help us provide a better diagnosis that can determine if the neurofibroma is becoming a malignant tumor or not,” Eilber said. “But more importantly, the loss of the PTEN and its associated signaling pathways gives us targets for therapy and it may lay the foundation for treatment in other sarcomas as well.”