TUESDAY, September 24, 2013 — Many studies have shown survivors of pediatric cancer are at higher risk for serious chronic diseases in adulthood. Kids who receive common cancer treatments, such as radiation and chemotherapy, are more likely to experience lifelong endocrine, reproductive, musculoskeletal, and neurologic problems. Now, a newly published study finds that decline in kidney function should be added to the list of later-life health risks for pediatric cancer survivors.This is the first study to examine the rate at which renal function decline occurs in pediatric cancer survivors.
The study, published in the journal Cancer Epidemiology, Biomarkers & Prevention, examined renal function in adults who had a history of childhood lymphoma, leukemia, or tumors, and had had certain chemotherapy treatments, radiation, and/or surgery. The researchers found these patients had worse renal function than adults who were not childhood cancer survivors and hadn't undergone cancer treatment; they also found that the cancer survivors' kidney function didn't improve over time. As a result of poor renal function, former pediatric cancer patients are at higher risk for premature kidney failure.
"We know that childhood cancer survivors have an increased risk for impaired kidney function after specific cancer therapy," said Renée Mulder, PhD, a professor in the department of pediatric oncology at the Emma Children's Hospital/Academic Medical Center in Amsterdam, The Netherlands, and the study's lead author.
"However, until now, we didn’t know if the glomerular function worsened over time or not, and which patients have a worse decline in kidney function than others." Glomeruli are small blood vessels that act as filters for the kidneys.
The researchers looked at data on 1,122 adults who were pediatric cancer survivors. All were over age 18, and had visited the Late Effects of Childhood Cancer outpatient clinic at the Emma Children's Hospital between 1996 and 2010. Physicians followed patients at this clinic for 2 to 42 years. During each follow-up period, 15 percent of these patients had at least one abnormal kidney test result, including those survivors who hadn't been treated with nephrotoxic (damaging to the kidneys) chemotherapy drugs — such as ifosfamide, cisplatin, carboplatin, high-dose methotrexate, or high-dose cyclophosphamide.
Patients who underwent radiation therapy that targeted the area of the body close to the kidneys, or had undergone surgery to remove part or all of the kidney, also showed increased risk for renal disease. These cancer treatments were associated with lower glomerular filtration rate (GFR), a test used to assess a person's kidney function. The GFR test measures the amount of blood per minute that passes through the kidney's filters.
When the GFR is below 60 for three months or more the patient is considered to have chronic kidney disease. The GFR of childhood cancer survivors treated with therapies that are toxic to the kidneys declines approximately 10 units per 10 years, explained Mulder. But she added that it's difficult to predict how long it may take for someone with poor glomerular function to go into kidney failure.
Monitoring the Health of Pediatric Cancer Survivors
Daniel Mulrooney, MD, assistant faculty member at the St. Jude Children's Research Hospital division of cancer survivorship in Memphis, said the study is significant because it underscores the importance of monitoring the kidney health of pediatric cancer survivors, in addition to monitoring the body's other organ systems, such as the heart, lungs and endocrine system.
Dr. Mulrooney added that symptoms of kidney failure often go undetected because a patient can be asymptomatic for months and years at a time, and the condition is typically discovered in routine blood and urine tests. "We do see this in our clinic quite frequently," he said. "Oftentimes, survivors themselves are not aware of their risks. Oftentimes, survivors are not being followed appropriately. That’s not anyone's fault. There’s an increasing number of survivors with these toxicities, and we need to ensure pediatric cancer survivors stay healthy."
Approximately 13,000 children in the United States are diagnosed with cancer each year. According to the Children's Cancer Research Fund, around 80 percent of all pediatric cancers are curable. But the majority of these patients develop at least one serious health condition as adults, whether it's a subsequent cancer or a serious chronic illness such as kidney disease.
A recent study conducted at St. Jude Children's Research Hospital and published in JAMA followed 1,700 pediatric cancer survivors, and found that by age 45, some 80 percent of these patients had at least one life-threatening condition. Conditions detected and diagnosed during the study included new cancers, abnormal heart and lung function, and neurocognitive difficulties. Around 65 percent of survivors were identified as being at risk for lung problems, while endocrine problems were diagnosed in 61 percent of survivors. Heart function abnormalities were found in 56 percent, and 48 percent were identified as having cognitive impairment.
A Cancer Survivor's Story
Cheryl Moring, a 51-year-old elementary school art teacher from New Edinburg, Ark., is a survivor of acute lymphoblastic leukemia (ALL). When Moring was diagnosed, at the of 5, her doctors gave her six months to live. At St. Jude, Moring underwent chemotherapy and cranial irradiation, a standard treatment at the time for ALL that has metastasized to the central nervous system. Cranial irradiation can have long-term impacts on a survivor's cognitive abilities and intellectual functioning. And although Moring's cancer went into remission four years later, when she was 9, she's had to contend with a range of health challenges ever since.
"I'd rather have limitations as opposed to what would have happened," said Moring. "I can remember my mom talking to my aunts one time. 'She'll have limitations, she's not going to be able to perform.' I kind of took that in without knowing what it meant. It kind of stuck in me like a burr."
Studies like the new one in Cancer Epidemiology point to the need to develop not just better and safer cancer treatments for children, sais Mulrooney, but also adult health care that takes into account a patient's cancer treatment history. He said doctors should conduct screenings for conditions for which a pediatric cancer survivor is higher risk. And patients and families must follow up on after-cancer care.
"I think today we’re much more aware of the long-term effects of childhood cancer treatment," said Mulrooney. "My experience has been parents and families often ask for that information."
Last Updated: 9/24/2013