phototherapy to treat
neonatal jaundice
Photo by Martin Pot
Two new studies raise questions about a possible link between childhood cancer and phototherapy for newborn jaundice.
One study showed a significant positive association between phototherapy and 2 cancer types—myeloid leukemia and kidney cancer—but the other study did not.
Although these results are inconclusive, researchers say clinicians should exercise caution in prescribing phototherapy for infants whose jaundice is likely to resolve on its own.
However, the findings should not discourage the use of phototherapy in infants who otherwise would be at risk of brain damage or hearing loss.
The studies were published in Pediatrics alongside a related editorial.
“Phototherapy has been perceived by most as causing minimal risk to the infant,” said editorial author A. Lindsay Frazier, MD, of the Dana-Farber Cancer Institute in Boston, Massachusetts.
“Although these studies are inconclusive and do not prove a relationship between phototherapy and cancer, they should give us pause. That being said, however, the brain damage and hearing loss from high bilirubin levels are real and well-documented, and the suggested risk of cancer from these new studies is both unclear and very small.”
Kaiser Permanente study
Thomas B. Newman, MD, of University of California, San Francisco, and his colleagues conducted a study of children born in Kaiser Permanente Northern California hospitals from 1995 to 2011. The researchers analyzed data on 499,621 children born at 35 weeks’ gestation or later.
There were 60 cases of cancer among the 39,403 children exposed to phototherapy and 651 cases of cancer among the 460,218 children who were not exposed to phototherapy. That translates to 25 per 100,000 person-years and 18 per 100,000 person-years, respectively, for an incidence rate ratio (IRR) of 1.4 (P=0.01).
In an unadjusted analysis, phototherapy was associated with increased rates of any leukemia (IRR=2.1, P=0.0007), nonlymphocytic leukemia (IRR=4.0, P=0.0004), and liver cancer (IRR=5.2, P=0.04).
However, when the researchers adjusted for bilirubin levels, chromosomal disorders, congenital anomalies, and other covariates, these associations were no longer statistically significant.
Study of California hospitals
Andrea C. Wickremasinghe, MD, of Kaiser Permanente Northern California in Santa Clara, and her colleagues conducted a study of children born in California hospitals from 1998 to 2007.
The team analyzed data from the California Office of Statewide Health Planning and Development, which included 5,144,849 infants born at 35 weeks’ gestation or later.
There were 58 cases of cancer among the 178,017 infants exposed to phototherapy and 1042 cancer cases among the 4,966,832 infants who were not exposed to phototherapy. That translated to 32.6 per 100,000 and 21.0 per 100,000, respectively, for a relative risk of 1.6 (95% confidence interval [CI], 1.2–2.0; P=0.002).
In propensity-adjusted analyses, there were significant positive associations between phototherapy and overall cancer (adjusted odds ratio [aOR]=1.4; 95% CI, 1.1–1.9; P=0.007), myeloid leukemia (aOR=2.6; 95% CI, 1.3–5.0; P=0.005), and kidney cancer (aOR=2.5; 95% CI, 1.2–5.1; P=0.02).
Dr Frazier noted that these studies come at a time when the number of infants receiving phototherapy is increasing, perhaps because of the availability of light therapy units that can be used in the home. In the Kaiser Permanente study, 15.9% of infants received phototherapy in 2011, compared to 2.7% in 1995.
“What is concerning is the fact that, at least in the Kaiser Permanente Northern California healthcare system, the number of children receiving phototherapy has dramatically increased,” Dr Frazier said.
“The risks associated with such a prevalent exposure require close scrutiny. If I were the one prescribing phototherapy today, I would want to be sure it was indicated.”
