Link Between Light Therapy for Newborn Jaundice and Childhood Cancer Inconclusive

Although a pair of studies showed inconclusive results for the potential link between light therapy for newborn jaundice and childhood cancers, researchers stress that clinicians should take caution when prescribing the treatment.

The 2 studies published in Pediatrics analyzed the association between pediatric cancers and phototherapy. The California Late Impact of Phototherapy Study (CLIPS), the first of the studies, gathered and evaluated data from 5 million infants born in California hospitals between 1998 and 2007.

Administrative data that linked the phototherapy billing code and childhood cancer diagnosis code was used in CLIPS. The results of the study showed that the strongest association was found in a 1.6-fold increased risk of acute myeloid leukemia (AML).

Additionally, there was an increased statistical significance found in the risk of Wilms tumor.

The second study, called the Late Impact of Getting Hyperbilirubinemia of photoTherapy (LIGHT) study, analyzed data from 500,000 children. The children were born between 1995 and 2011 in the Kaiser Permanente Northern California health care system.

The results of the LIGHT study revealed that there was no statistically significant association between childhood cancer and phototherapy. However, there was an association found with AML.

“Even though the results are inconclusive, they are worrisome enough that phototherapy should not be presented as risk-free,” said lead study author Lindsay Frazier, MD. “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. 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. The risks associated with such a prevalent exposure require close scrutiny.”

A Kaiser study found a 16% increase in 2011 of infants receiving phototherapy, a 3% increase from 1995. Researchers suggest this could be due to light therapy units that are no available to be used at home.

“Studying why children get cancer is very difficult because it is such a rare disease,” Frazier said. “The association between smoking and lung cancer was relatively easy to detect because the disease is well over 10 times more common than childhood cancer. There are about 225,000 new cases of lung cancer a year in the United States, versus 15,000 new cases of pediatric cancer. Thus, to study childhood cancer, a scientist needs to find a way to study large populations. The authors are to be commended for finding a way to do just that. But even in these studies of huge populations, the number of children who actually develop cancer remains quite small.”

Despite the CLIPS study showing a statistically significant association between childhood cancer and phototherapy, the absolute numbers were still very low. There were 58 infants who received phototherapy out of 5 million in the study who developed cancer.

Although the numbers are low, authors advise clinicians to weigh the possible link with cancer when deciding which infants are in need of phototherapy.

“In the end, acknowledging that the information is imperfect, general pediatricians and neonatologists must make a choice,” the authors wrote. “These data suggest that phototherapy may not be harmless, and that the risks as well as the benefits need to be weighed before flipping the switch.”