Among more than 2,300 adult survivors of childhood cancer and their siblings, who served as controls, new-onset memory impairment emerged more often in survivors decades later.
The increased risk was associated with the cancer treatment that was provided as well as modifiable health behaviors and chronic health conditions.
Even 35 years after being diagnosed, cancer survivors who never received chemotherapies or radiation therapies known to damage the brain reported far greater memory impairment than did their siblings, first author Nicholas Phillips, MD, told this news organization.
What the findings suggest is that “we need to educate oncologists and primary care providers on the risks our survivors face long after completion of therapy,” said Dr. Phillips, of the epidemiology and cancer control department at St. Jude Children’s Research Hospital, Memphis, Tenn.
The study was published online in JAMA Network Open.
Cancer survivors face an elevated risk for severe neurocognitive effects that can emerge 5-10 years following their diagnosis and treatment. However, it’s unclear whether new-onset neurocognitive problems can still develop a decade or more following diagnosis.
Over a long-term follow-up, Dr. Phillips and colleagues explored this question in 2,375 adult survivors of childhood cancer from the Childhood Cancer Survivor Study and 232 of their siblings.
Among the cancer cohort, 1,316 patients were survivors of acute lymphoblastic leukemia (ALL), 488 were survivors of central nervous system (CNS) tumors, and 571 had survived Hodgkin lymphoma.
The researchers determined the prevalence of new-onset neurocognitive impairment between baseline (23 years after diagnosis) and follow-up (35 years after diagnosis). New-onset neurocognitive impairment – present at follow-up but not at baseline – was defined as having a score in the worst 10% of the sibling cohort.
A higher proportion of survivors had new-onset memory impairment at follow-up compared with siblings. Specifically, about 8% of siblings had new-onset memory trouble, compared with 14% of ALL survivors treated with chemotherapy only, 26% of ALL survivors treated with cranial radiation, 35% of CNS tumor survivors, and 17% of Hodgkin lymphoma survivors.
New-onset memory impairment was associated with cranial radiation among CNS tumor survivors (relative risk [RR], 1.97) and alkylator chemotherapy at or above 8,000 mg/m2 among survivors of ALL who were treated without cranial radiation (RR, 2.80). The authors also found that smoking, low educational attainment, and low physical activity were associated with an elevated risk for new-onset memory impairment.
Dr. Phillips noted that current guidelines emphasize the importance of short-term monitoring of a survivor’s neurocognitive status on the basis of that person’s chemotherapy and radiation exposures.
However, “our study suggests that all survivors, regardless of their therapy, should be screened regularly for new-onset neurocognitive problems. And this screening should be done regularly for decades after diagnosis,” he said in an interview.
Dr. Phillips also noted the importance of communicating lifestyle modifications, such as not smoking and maintaining an active lifestyle.
“We need to start early and use the power of repetition when communicating with our survivors and their families,” Dr. Phillips said. “When our families and survivors hear the word ‘exercise,’ they think of gym memberships, lifting weights, and running on treadmills. But what we really want our survivors to do is stay active.”
What this means is engaging for about 2.5 hours a week in a range of activities, such as ballet, basketball, volleyball, bicycling, or swimming.
“And if our kids want to quit after 3 months, let them know that this is okay. They just need to replace that activity with another activity,” said Dr. Phillips. “We want them to find a fun hobby that they will enjoy that will keep them active.”
The study was supported by the National Cancer Institute. Dr. Phillips has disclosed no relevant financial relationships.
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