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Cognitive outcomes after proton radiation therapy
Source: Late Effects of Treatment for Childhood Cancer (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: April 14, 2025 · Captured 2026-09-09.
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Data are emerging regarding cognitive outcomes after proton radiation to the CNS.[50-52] However, these studies have been limited by retrospective analysis of cognitive outcomes among relatively small clinically heterogenous pediatric brain tumor cohorts and the use of historically treated photon patients or population standards as comparison groups.
In studies largely describing IQ changes during early follow-up (<5 years from radiation), results demonstrate lack of difference in slopes of IQ change among photon-treated and proton-treated patients [50] and significant declines in cognitive processing speed among patients treated with proton radiation.[51]
One study compared the intellectual trajectories between pediatric patients with medulloblastoma who were treated with proton and photon radiation therapy (4.3-year mean follow-up after median 23.4-Gy craniospinal irradiation dose). Notably, boost dose and margins were significantly different between the two groups.[52]
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One study compared the intellectual trajectories between pediatric patients with medulloblastoma who were treated with proton and photon radiation therapy (4.3-year mean follow-up after median 23.4-Gy craniospinal irradiation dose). Notably, boost dose and margins were significantly different between the two groups.[52]
Children treated with proton radiation therapy exhibited superior long-term outcomes in global IQ, perceptual reasoning, and working memory compared with children who were treated with photon radiation therapy.
One study compared the intellectual trajectories between pediatric patients with medulloblastoma who were treated with proton and photon radiation therapy (4.3-year mean follow-up after median 23.4-Gy craniospinal irradiation dose). Notably, boost dose and margins were significantly different between the two groups.[52]
The photon radiation therapy group exhibited a significant decline in global IQ, working memory, and processing speed.
One study compared the intellectual trajectories between pediatric patients with medulloblastoma who were treated with proton and photon radiation therapy (4.3-year mean follow-up after median 23.4-Gy craniospinal irradiation dose). Notably, boost dose and margins were significantly different between the two groups.[52]
The proton radiation therapy group exhibited stable scores over time in all domains, except for processing speed.
Considering the relatively brief follow-up time from radiation, longitudinal follow-up is important to determine whether proton radiation provides a clinically meaningful benefit in sparing cognitive function compared with photon radiation. In addition, more targeted radiation treatment volumes with photons may diminish potential differences.
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