SAN FRANCISCO, May 23 (UPI) -- Newborns with jaundice are often treated with phototherapy, and some without jaundice receive it as a precautionary measure, however two recent studies suggest the treatment increases risk for cancer.
The two studies published in the journal Pediatrics showing the slight increase in risk confirms concerns of some doctors, researchers say, and could lead to less use of the treatment.
Phototherapy consists of exposing infants to blue light, which is close to ultraviolet light on the light spectrum. Infants with jaundice -- caused by high levels of bilirubin, a byproduct of the breakdown of old red blood cells -- are exposed to the light, which changes the shape of the molecule, allowing the body to excrete it properly.
Cancer in infants is rare, though babies with Down syndrome are at higher risk, making it difficult to study, researchers said.
The recent studies, one of California medical records and the other of Kaiser Permanente members in Northern California, did not show a dramatic increase in risk, but researchers say any increased risk for cancer is worth considering when deciding on treatment.
"Even though the results are inconclusive, they are worrisome enough that phototherapy should not be presented as risk-free," Dr. Lindsay Frazier, a researcher at the Dana-Farber Cancer Center and Boston Children's Hospital, and lead author of an editorial published alongside the two studies, said in a press release. "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."
For a study conducted at the University of California San Francisco, published in the journal Pediatrics, researchers reviewed birth certificates, death certificates and hospital discharge abstracts for 5,144,849 infants born in California hospitals between 1998 and 2007.
The researchers found cancer was diagnosed in 58 of 178,017 infants treated with phototherapy and 1,042 out of 4,966,832 infants not treated with blue light. Although the absolute risk was small, the researchers say the difference should be considered, with infants who do not have high bilirubin levels not treated with light for prevention of jaundice.
In a separate UCSF study, also published in the journal Pediatrics, researchers reviewed records for 499,621 children born between 1995 and 2011 at Kaiser Permanente Northern California hospitals.
Among 39,403 children who received phototherapy, 60 were diagnosed with cancer, compared to 651 of 460,218 children who did not receive the treatment. In the study, researchers linked phototherapy with increased rates of leukemia, nonlymphocytic leukemia and liver cancer. Although the risk was higher among children receiving blue light, researchers say the link was canceled out when controlling for other health factors.
In both cases, researchers say increases in the use of phototherapy -- regardless of how big cancer risk may be -- is concerning because there is even a slight risk for cancer.
"A lot of phototherapy is being given to babies whose bilirubin never reached the level recommended for treatment," Dr. Thomas Newman, a professor of epidemiology and biostatistics and pediatrics at the University of California San Francisco, said in a press release. "Phototherapy is being given to babies just in case, to prevent readmission later. Although the risk of cancer is small -- no more than one in 1000 for most babies -- and still must be regarded as uncertain, it is probably prudent to save phototherapy for the babies who most need it."
[CORRECTION: A previous version of this story incorrectly attributed the second study to the Dana Farber Cancer Institute. It was conducted by researchers at the University of California, San Francisco.]