Late Effects: Cognitive Changes That Can Result From Cancer Treatment

Interviews with families and patients show that a cancer diagnosis and treatment is unbelievably stressful and draining, and it feels as though a child who survives surgery, radiation, chemotherapy and any other issues and complications that come their way has certainly dealt with enough. Unfortunately, survivors of childhood brain tumors frequently develop problems after the initial battle is won, in the areas of intellectual ability, academic achievement, memory, and attention. Cognitive changes are not uncommon among brain tumor survivors, however, the extent to which any one change will take effect depends on many different factors, including tumor location and surgery, age at diagnosis and treatment with radiation therapy.

Neurological problems such as seizures and muscle coordination problems are relatively common among childhood brain tumor survivors. These sorts of disabilities often develop around the time of diagnosis or after initial surgery, but sometimes they may first appear months to years after diagnosis. Radiation injury to the brain may, on rare occasions, cause delayed neurological problems that may become not become apparent until 10 or more years after treatment.

Neurosensory problems such as impaired vision and hearing may also develop, both early in the course of diagnosis and treatment and years after treatments are finished. Radiation can cause delayed visual problems through several different mechanisms. Direct damage to the eye nerves (optic nerves) can infrequently result in visual changes years after treatment. In rare instances, previous radiation can produce cataracts in the eyes that can interfere with normal vision. If your child has had surgery near the eye or eye nerves or has had radiation to the head, regular visits to an eye specialist (ophthalmologist) are highly recommended. Hearing difficulties are also common after treatment for brain tumors and, in general, remain stable or even decrease in severity over time. Under certain circumstances, though, hearing problems have been shown to get worse or appear for the first time months to years after treatment ends. Children who receive treatment with the combination of the drug cisplatin and radiation to the brain appear to be at the greatest risk for developing delayed hearing problems. Periodic hearing tests should be performed for all children at risk for hearing problems as well as for any child who is experiencing academic or learning difficulties.

Learning disabilities are particularly common among brain tumor survivors and are difficult and frustrating. Many children with learning disabilities require special education services at school. Moreover, one may observe deterioration in function over time, particularly in children who were treated with radiation to the brain at a young age. Like any other problematic issue, early detection of a problem is the best way to combat it, and this assessment is best accomplished by working closely with a pediatric neuropsychologist who has experience working with children with brain tumors. As symptoms may develop over time, it is extremely important to reassess cognitive functioning periodically in all survivors who are at high risk, as well as in survivors who are experiencing academic difficulties. This is done by administering a battery of tests known as psychometric or neuropsychological tests.

Most major medical centers will have trained neuropsychologists on staff, as will many schools, who can administer these exams. It is critical at the time of testing that you have available to you a detailed history of your child's previous therapy. This should include the exact diagnosis and date of diagnosis, the names, modalities and total doses of all chemotherapy drugs, the doses and sites of all previous radiation therapy, the sites of all surgeries, and the start and stop dates for each treatment. This information can usually be obtained from the team supervising your child's cancer therapy. At the end of treatment, it's a good idea for you to ask your child's neuro-oncology team to review with you the treatments your child received as well as any late effects that might occur as a result of these therapies. If appropriate, this may be the time to begin to make arrangements for follow-up treatment with specific specialists (for example, a neuropsychologist or pediatric endocrinologist), as preparing for your child's follow-up care early, at the end of planned therapy, helps ensure a smooth transition from treatment to life after treatment.

"We created a medical data sheet to hand over to all new medical professionals we came into contact with. It was helpful that we maintained our journal even after treatment ended, for over the years, it is a quick and easy resource to rely on."
-Parent of Brain Tumor Survivor

If problems are identified, then the school must provide your child with appropriate services. Although this is now mandated by federal law, you and the members of the medical team may need to advocate for your child to get all the services to which he or she is entitled.

Late effects are new problems that can occur months to years after therapy has ended. Whether or not a child will develop a late effect depends on a number of factors. The most important of these factors include the type and amount of treatment an individual received (for example, radiation therapy, specific chemotherapy drugs) and the child's age at the time of treatment. Other factors include the type of tumor and its location within the brain. In general, children who are treated at a young age (younger than 7 years) and those who receive the most intensive therapy (for example, high doses of radiation combined with high doses of several chemotherapy drugs) are more likely to develop late effects.

However, it is important to remember that everyone is unique and that no two people react in exactly the same way to a given treatment. Equally important is that being at risk for a given problem does not necessarily mean a child will develop the problem. Clearly, knowing the details of your child's cancer treatments is essential and will help your child's health care providers, both current and future, determine which late effects your child may develop over time. Knowledge is power and it can only help you to combat cognitive problems that may arise.