Oncology Certified Nurse (OCN) Nursing Practice Test

What late effect is associated with radiation therapy to the central nervous system?

1. Blindness

2. Adhesions

3. Hyperplasia

4. Pulmonary fibrosis

The correct answer is: Blindness

Radiation therapy to the central nervous system can lead to several late effects due to the sensitivity of brain tissues and surrounding structures to radiation. Blindness is a recognized potential late effect when radiation affects areas of the brain responsible for vision, particularly if the optic nerves or the visual pathways are involved in the treatment field. The risk of blindness may result from radiation-induced damage to the optic nerves, leading to vascular changes, necrosis, or even changes within the eye itself. This is particularly important in pediatric populations who may undergo cranial radiation as part of a treatment regimen for conditions such as brain tumors, as their developing optic pathways can be severely impacted. While other late effects such as adhesions, hyperplasia, and pulmonary fibrosis can occur in different contexts of radiation therapy, they are not typically associated with central nervous system radiation. Adhesions are more relevant in abdominal or pelvic radiation, hyperplasia may be seen in tissue that has been irradiated but is not a primary concern for CNS therapy, and pulmonary fibrosis is associated with thoracic radiation. Thus, blindness is the most appropriate late effect related to radiation therapy targeting the central nervous system.