Children diagnosed with craniopharyngioma, a rare brain tumor, have a better chance of avoiding neurocognitive deficiencies long-term if treated with proton therapy instead of photon radiotherapy.

In a phase 2 clinical trial, St. Jude Children’s Research Hospital observed similar survival rates between both treatments but improved neurocognitive outcomes in patients who received proton therapy for their craniopharyngiomas, which are challenging to treat due to consistently being located in the central part of the brain where they are associated with the central blood supply, optic nerves and chiasm, hypothalamic-pituitary axis, and other critical areas that affect cognitive functioning.

The authors evaluated progression-free survival and cognitive outcomes for five years after treatment, making this the first prospective longitudinal study comparing proton therapy to 3D conformal photon therapy in children with this tumor.

Principal investigator Thomas Merchant, St. Jude Department of Radiation Oncology chair, says that with more research, the treatment could become recommended more over radical surgery and radiotherapy, potentially making it the new gold standard for pediatric patients with craniopharyngioma.

Between 2011 and 2016, researchers treated 94 patients with proton therapy and surgery, and compared them to a control group that received photon radiotherapy and surgery. Prior to treatment, they performed surgical assessments on individual participants, which included no surgery, single procedures with catheter and Ommaya reservoir placement through a burr hole or craniotomy, endoscopic resection, trans-sphenoidal resection, craniotomy, or multiple procedure types.

For the proton group, survival was 93.6%, compared to 90% for photon radiotherapy. Those treated with traditional radiotherapy experienced a loss of 1.09 IQ points on average annually, as well as a loss of 1.48 adaptive behavior points, according to an annual parental report that consists of child assessments on the basis of insights gained from parents self-reporting behavioral skills. Additionally, those treated with proton therapy saw their cognitive deficits stabilized by the end of the study.

Progression was seen in three of the 94 patients at the three-year mark, but no deaths occurred by then. At five years, two had experienced necrosis; four, severe vasculopathy; three, permanent neurological conditions; and decline in vision from normal to abnormal in four participants who had normal vision at the beginning of their treatment.

The findings were published in Lancet Oncology.

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