NEW YORK (Reuters Health) - Pediatric central nervous system (CNS) tumor survivors face an increased risk of severe neurocognitive impairment as adults, even if they have not undergone cranial radiation therapy (CRT), according to new findings.
"These impairments may not be recognized or reported by survivors but have a significant impact on the ability of these survivors to attain expected adult milestones, including graduating from college and securing employment," corresponding author Dr. Tara Brinkman of St. Jude Children's Research Hospital in Memphis told Reuters Health by email. The findings were published online February 1 in the Journal of Clinical Oncology.
More than 75% of patients diagnosed in childhood with CNS tumors will survive for at least five years, Dr. Brinkman and her team noted. Given that CRT is known to increase the risk of neurocognitive impairment in these patients, they added, newer protocols aim to reduce the amount of healthy brain tissue exposed to radiation. While reducing radiation dose and target volume reduces cognitive morbidities in these patients early on, the effect of conformal radiation on outcomes for adult survivors has not been investigated.
The researchers looked at 224 CNS tumor survivors treated at St. Jude Children's Research Hospital, with a median age of 26 and a median time from diagnosis of 18 years. Patients were compared across three treatment groups: no CRT, focal irradiation, or craniospinal irradiation. Patients were considered to have severe neurocognitive impairment if their test results in a given area were at least two standard deviations below normal.
Patients who had craniospinal irradiation were 1.5 to three times as likely as those who did not receive CRT to have severe impairment in an area of cognitive function, the researchers found. Seizures and hydrocephalus with shunt placement were also associated with greater impairment of intelligence and memory, while seizures also increased the risk of impaired attention. But even patients who did not undergo CRT showed impairment in some cognitive measures.
The researchers also found that while less than 10% of survivors self-reported severe cognitive or behavioral impairment, performance-based measurements found up to 50% of the survivors had this degree of impairment.
Neurocognitive impairment was also associated with a greater likelihood of lower educational attainment, unemployment, and non-independent living, Dr. Brinkman and her team found.
"There are several factors that may account for the observed impairment in survivors who did not receive CRT," she said. "These may include tumor location/infiltration, as well as the effects of the tumor on the developing brain. For example, we found that tumor location within the infratentorial region of the brain was associated with increased risk of intellectual impairment."
She added: "These results highlight the need for systematic monitoring of cognitive function throughout the course of survivorship; we plan to continue to follow these survivors to better understand cognitive aging in adult survivors of pediatric brain tumors. In addition, these results underscore the importance of identifying effective cognitive interventions with the potential to impact daily function."
"Research on prophylactic interventions is emerging," Dr. Brinkman said. "To date, studies examining the prevention of cognitive problems has focused on academic skills such as reading and math. Current studies are examining the potential role of computerized training of specific cognitive skills during treatment, but the effectiveness of these approaches for the prevention of deficits is currently unknown."
The authors reported no funding. Three coauthors reported disclosures.