Quality of life in relation to symptoms specific to brain cancer will be assessed using the European Organization for the Research and Treatment of Cancer (EORTC) Quality of Life Questionnaires (QLQ). Brain cancer-specific symptoms will be assessed at baseline and follow-up evaluations using EORTC-QLQ-BN20.

Mixed effects models will be used to analyze the repeated measures of EORTC-QLQ with participant-specific intercepts and slopes assumed as random effects. Tumor type will be modeled as fixed effects in order to estimate quality of life changes over time among participants with each benign and malignant diagnosis.

State anxiety and depression will be measured with the Hospital Anxiety and Depression Scale (HADS). HADS screens for mood disorders in medically ill participants; it focuses on subjective rather than physical symptoms, which may be confounded with illness.

Mixed effects models will be used to analyze the repeated measures of HADS with participant-specific intercepts and slopes assumed as random effects. Tumor type will be modeled as fixed effects in order to estimate mood changes over time among participants with each benign and malignant diagnosis.

Those participants determined to have had proton radiation exposure to any part of the optic pathway that could potentially affect vision will undergo standard afferent neuro-ophthalmological evaluation, which includes tests of visual acuity, color perception, pupillary function, visual field testing, and optic disc appearance. Participants with any tumor type will be evaluable for visual outcome if the battery of neuro-ophthalmology evaluation were performed at baseline. Testing will be discontinued if the participant becomes blind.

The cumulative incidence of developing vision loss among evaluable participants will be analyzed with failure defined as decline in one or more of the vision function tests and with competing risks of progressive disease and death.

For participants with proton radiation exposure to the skull base audiologic system, standard audiologic testing will be performed, unless poor hearing inadequate for useful function is present at baseline. Testing will be discontinued if the participant becomes deaf. Participants with any tumor type will be evaluable for hearing outcome if audiology evaluation were performed at baseline.

The cumulative incidence of developing ototoxicity among evaluable participants will be analyzed with failure defined as significant decrease in Pure Tone Average or/and Word Recognition Score and with competing risks of progressive disease and death

Participants will be candidates for neuroendocrine testing if they were determined to have any radiation exposure to the hypothalamus or pituitary gland or to have a target lesion within 2 cm of either of these normal structures, unless panhypopituitarism is present at baseline. Participants with any tumor type will be evaluable for endocrine outcome if neuroendocrine evaluation were performed at baseline.

The cumulative incidence of developing neuroendocrine dysfunction among evaluable participants will be analyzed with failure defined as any hormonal deficiency confirmed by test criteria and with competing risks of progressive disease and death.

Participants with any tumor type will be evaluable for neurocognitive analysis if the optional neuropsychological evaluation were performed at baseline and/or at least one follow-up. Mixed effects models will be used to analyze the repeated measures of intelligence, language, visuospatial/motor functioning, learning/memory and attention/executive functioning, with participant-specific intercepts and slopes assumed as random effects. Tumor and treatment characteristics may be modeled as fixed effects in order to estimate their effects on neurocognitive changes over time.

Participants with any tumor type will be evaluable for alopecia unless they are virtually bald at baseline and graded using Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Maximal hair loss will be documented between the last week of radiation and 4 weeks later, while permanent hair loss will be defined at 2 years post-treatment.

Participants with any tumor type will be evaluable for CD4 analysis if they were to consent to the optional assessment of CD4 count. The worst grade of CD4 count will be defined using Common Terminology Criteria for Adverse Events (CTCAE) version 4.0 during the short term (on-treatment and 1 to 3 months post-radiation) and long term (6 months to 2 years post-radiation).