A common treatment for babies with jaundice may increase their risk of cancer, doctors have warned.
They suggest that the light therapy given to thousands of newborns each year could trigger leukaemia and kidney cancer in the weeks and months to come.
While the link isn’t definite, they said that phototherapy may not be as safe as previously believed and doctors should think carefully before prescribing it.
Researchers from the University of California, San Francisco, analysed data on more than 5 million children born in the US between 1998 and 2007. This included whether they were diagnosed with jaundice, the treatment given and whether they developed cancer before their first birthday. About 14 percent had jaundice and 3.5 percent received phototherapy. Those given this treatment were 40 percent more likely to be diagnosed with cancer overall.
However, their risk of an aggressive form of blood cancer called acute myeloid leukaemia was more than double. The odds of a form of kidney cancer were similarly raised.
The researchers cautioned that the actual risk of cancer was still low. Yet they added: “This risk needs to be considered when making phototherapy treatment decisions.”
The treatment, in which blue light is shone on a baby’s skin, is widely used to combat jaundice – one of the most common newborn conditions.
Characterised by yellowing of the skin, it occurs when the child’s liver is too immature to break down bilirubin, a waste product from the blood.
It usually clears up without treatment. But prolonged high levels of bilirubin can cause brain damage and deafness, and one in 20 babies with jaundice is treated either with light therapy or a blood transfusion. The intensive light breaks down the bilirubin, making it easier to be cleared from the body. While previous British research has given phototherapy a clean bill of health, other studies have linked it to cancer.
However, paediatric cancer is so rare that huge numbers of babies need to be studied to be confident of the result. And a second study from the same university failed to find such strong evidence. But it did hint at a link, and the authors said: “Avoiding unnecessary phototherapy may be prudent.”
In an accompanying editorial in the influential journal Pediatrics, doctors from the top paediatric cancer centre in the US – the The Dana-Farber Boston Children’s Cancer Centre – said that while inconclusive, the results were “worrisome”.
They stressed that in severe cases, the benefits of phototherapy far outweigh the risks. But they also expressed concern that the treatment is becoming more common – and said doctors should consider whether babies really need it.
They concluded: “These data suggest that phototherapy may not be harmless and the risks need to be weighed before flipping the switch.”
Sarah Williams, from the charity Cancer Research UK, said: “The results aren’t conclusive… More research will be needed to confirm if there is any link between this treatment and cancer.
“Phototherapy is an important treatment option for some babies with neonatal jaundice and it’s important to bear in mind that only a small number of children who had phototherapy in these studies also developed childhood cancer.”
Professor Alan Craft, of the Royal College of Paediatrics and Child Health, said: “It is interesting but for those babies who need phototherapy, the benefits vastly out way any possible minuscule harm.
“However babies should only have phototherapy if they need it.”