When Cancer Strikes Twice

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Tumours caused by previous treatments are found to be different from those occurring naturally.
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Though a rare occurrence, therapy for a childhood cancer can lead to new brain tumours that form decades later.

Radiation therapy is an invaluable tool for treating cancer that can help save lives, particularly in childhood cancers. Unfortunately, the treatment itself can cause genetic damage and lead to new tumours that appear decades later.

A team led by PM Cancer Centre Scientist Dr. Gelareh Zadeh and Senior Scientist Dr. Kenneth Aldape studied radiation-induced meningiomas (RIMs)—a type of brain tumour that occurs 10-15 years after radiation therapy for childhood cancer. They looked at the patterns of genetic abnormalities in these tumours and compared them to meningiomas that occur in the general population without prior radiation, called sporadic meningiomas.

They found that RIMs had a distinct genetic profile versus sporadic meningiomas. Nearly all RIMs had losses of chromosomes 1p and 22q, and twelve of the thirty-one tumours studied had particular kinds of mutations in NF2, a gene that helps control cell growth in the brain. None of the naturally occurring tumours had similar NF2 mutations. Furthermore, RIMs lacked mutations that are commonly found in meningiomas.

The findings have implications for survivors of childhood cancer and others who previously received radiation therapy. By providing insight into the type of meningiomas that develop decades after radiation therapy, researchers will be better equipped to identify therapeutic approaches to help these patients.

This work was supported by the MacFeeters-Hamilton Neuro-Oncology Research Program led by Dr. Kenneth Aldape, the Canadian Institutes of Health Research, Adam Coules research grant, the Wilkins Family Chair in Brain Tumor Research and The Princess Margaret Cancer Foundation.

Agnihotri S, Suppiah S, Tonge PD, Jalali S, Danesh A, Bruce JP, Mamatjan Y, Klironomos G, Gonen L, Au K, Mansouri S, Karimi S, Sahm F, von Deimling A, Taylor MD, Laperriere NJ, Pugh TJ, Aldape KD, Zadeh G. Therapeutic radiation for childhood cancer drives structural aberrations of NF2 in meningiomas. Nat Comms. 2017 Aug 4.