Radiation for Childhood Cancer May Lead to Adult Brain Tumors

In a new study, neuroscientists have figured out why so many long-term survivors of childhood cancer develop meningiomas, the most common adult brain tumor. They discovered that the cranial-spinal radiation treatment commonly used to treat childhood cancer causes genetic rearrangements in DNA that can eventually lead to meningiomas.

“It is an important clinical problem because it presents a paradoxical dilemma that while cranial-spinal radiation is needed to cure many childhood cancers, an unfortunate consequence is that 10 to 15 years following radiation treatment some survivors develop meningiomas,” said neuropathologist-scientist Dr. Ken Aldape, director of the MacFeeters-Hamilton Neuro-Oncology Research Program and Princess Margaret Cancer Centre at University Health Network.

The researchers compared and contrasted the biological workings of radiation-induced meningiomas (RIMs) to those of meningiomas which appear sporadically in the general population.

“Radiation-induced meningiomas appear the same on MRI and pathology, feel the same during surgery and look the same under the operating microscope,” said Dr. Gelareh Zadeh, associate professor in the Division of Neurosurgery at the University of Toronto and holder of the Wilkins Family Chair in Brain Tumor Research.

“What’s different is they are more aggressive, tend to recur in multiples and invade the brain, causing significant morbidity and limitations (or impairments) for individuals who survive following childhood radiation,” she said.

By understanding the biology of radiation-induced meningiomas, the researchers will be able to develop a stronger therapeutic strategy that could be implemented early on after childhood radiation to prevent the formation of these tumors in the first place, according to Zadeh.

For the study, the research team analyzed RIMs from patients who had received cranial-spinal radiation as children, the majority of whom (74 percent) had survived either leukemia or pediatric brain cancer.

Importantly, the researchers found that RIMs developed regardless of the radiation dose. They discovered this by collaborating with scientists in Germany where low-dose radiation was a common treatment many years ago for scalp ringworm.

“Our research identified a specific rearrangement involving the NF2 gene that causes radiation-induced meningiomas. But there are likely other genetic rearrangements that are occurring as a result of that radiation-induced DNA damage. So one of the next steps is to identify what the radiation is doing to the DNA of the meninges,” said Aldape.

“In addition, identifying the subset of childhood cancer patients who are at highest risk to develop meningioma is critical so that they could be followed closely for early detection and management.”

The new findings appear online in the journal Nature Communications.

Source: University Health Network