Note: CTSI Consultation Services (CS) biostatistics unit provided support for this research.
By Laura Kurtzman via UCSF.edu
Phototherapy, increasingly used to treat jaundiced infants, could very slightly raise the risk of pediatric cancers, particularly myeloid leukemia, according to epidemiological research published, online Monday, May 23, 2016 in Pediatrics.
At very high levels, bilirubin, a byproduct of the normal breakdown of old red blood cells, turns the skin and whites of the eyes yellow and can get into the brain, where it can cause cerebral palsy and hearing loss. Infants are susceptible to this condition, and in recent years, doctors have been treating it more aggressively with blue light therapy, which changes the shape of the bilirubin molecule and allows it to be excreted more easily.
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Among the Largest Studies to Date
The two studies are among the largest to date. One examined about 500,000 babies born at Kaiser Permanente Northern California between 1995 and 2011, the other more than 5 million babies born in California between 1998 and 2007.
Both datasets showed an association between phototherapy and some cancers – myeloid leukemia in both cases, liver cancer in the Kaiser study and kidney cancer in the statewide dataset. The Kaiser study, which included data on more factors that might lead to both phototherapy and cancer, found that most associations were no longer statistically significant after the researchers adjusted for these variables. However, there was an association with myeloid leukemia for babies who received higher doses of phototherapy, and this association persisted after the researchers adjusted for potentially confounding factors. The authors cautioned this result was based on only two babies who were treated twice or more with phototherapy.
“Health care providers should look at phototherapy the way they do other treatments, as having both benefits and potential risks,” said Andrea Wickremasinghe, MD, of Kaiser Permanente Santa Clara, lead author of the California study. “We should probably be more cautious about giving phototherapy, particularly to babies with Down syndrome and babies with bilirubin levels that are below the thresholds recommended for treatment. On the other hand, we would not want excessive concern about this low and uncertain cancer risk to frighten people away from phototherapy when it is needed.”
Other authors of the papers include Michael Kuzniewicz, MD, MPH, of UCSF and Kaiser Permanente Northern California Division of Research; Barbara Grimes, PhD, and Charles McCulloch, PhD, of UCSF; and Eileen Walsh, RN, MPH, of Kaiser.
The Agency for Healthcare Research and Quality (grant number R01HS020618), the Gerber Foundation and the American Academy of Pediatrics provided funding for this research. Statistical analysis was partially supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through UCSF-CTSI (grant number UL1 TR000004).