Study Finds Small Link Between Phototherapy and Infantile Cancer

MedicalResearch.com Interview with:

Dr-Andrea-Wickremasinghe

Dr. Andrea Wickremasinghe

Andrea C. Wickremasinghe, MD
Neonatologist
Kaiser Santa Clara California

MedicalResearch.com: What is the background for this study?

Response: Neonatal jaundice is common and is often treated with phototherapy. Phototherapy is typically considered to be benign. In the past decade, phototherapy use has increased and it is sometimes started at bilirubin levels below recommended treatment thresholds. Beginning in the 1970’s, in-vitro and in-vivo studies have shown phototherapy to be associated with cellular changes implicated in the pathogenesis of cancer. Epidemiologic studies have yielded mixed results, with some studies showing associations between phototherapy and leukemia and other studies failing to show this association. In this study, we used a large statewide administrative dataset to investigate the relationship between neonatal phototherapy and cancer in the first year after birth.

MedicalResearch.com: What are the main findings?

Response: We used a dataset that contained linked birth certificates, death certificates, and hospital discharge abstracts for 5,144,849 infants born in California at ≥ 35 weeks gestation between 1998 and 2007. Propensity adjusted analyses showed phototherapy to be associated with an increased odds of overall cancer (adjusted odds ratio [aOR] 1.4, 95% confidence interval [CI] 1.1-1.9), myeloid leukemia (aOR 2.6, 95% CI 1.3-5.0), and kidney cancer (aOR 2.5, 95% CI 1.2-5.1). The estimated number needed to treat with phototherapy to cause one additional cancer case by 1 year of age was about 10,000. The risk was higher in infants with Down syndrome (number needed to harm about 1300), given their increased baseline risk of cancer.

Our study suggests a small but statistically significant association between phototherapy and infantile cancer. This study was limited by the fact that as we used an administrative dataset, we were unable to adjust for potential confounding variables not included in the dataset (ex: bilirubin levels). The companion study by Newman et al, also published in this edition of Pediatrics, investigated the relationship between phototherapy and childhood cancer in a dataset of 499,621 individuals. That study found a crude association between phototherapy and childhood cancer, which was no longer statistically significant in analyses adjusted for potential confounding variables (including bilirubin levels).

MedicalResearch.com: What should readers take away from your report?

Response: Phototherapy is a valuable treatment for infants with extremely high bilirubin levels. We suggest that it should be considered like other medical therapies, as having both risks and benefits. Given the potential for a small but increased risk of cancer, it is prudent to be cautious when using phototherapy below recommended treatment thresholds and in infants with Down syndrome.

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Citation:

Andrea C. Wickremasinghe, Michael W. Kuzniewicz, Barbara A. Grimes, Charles E. McCulloch, Thomas B. Newman. Neonatal Phototherapy and Infantile Cancer. Pediatrics, May 2016 DOI: 10.1542/peds.2015-1353

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