Early Infection with Cytomegalovirus and Risk of Childhood Hematologic Malignancies

Congenital cytomegalovirus (CMV) infection was recently identified as a risk factor for childhood acute lymphocytic leukemia by detecting the presence of CMV sequences in neonatal blood spots. In this study, we asked whether clinically apparent CMV infection could be identified prior to hematologic malignancy, using high-quality Swedish population-based registries.

CMV infection was identified with appropriate ICD-9 or ICD-10 codes in the Patient and Medical Birth Registries, and childhood malignancies below the age of 15 years were identified in the Cancer Registry, among 2,782,507 children born in Sweden 1987 to 2014.

Observing all CMV infections registered earlier than 6 months prior to malignancy diagnosis, an increased HR of CMV-related infections, adjusting for congenital malformations, deformations, and chromosome abnormalities, was detected for hematologic malignancies [HR, 11.2; 95% confidence interval (CI), 5.8-21.5], but not for central nervous system tumors.

Higher CMV incidence was detected for children ostensibly exposed through maternal CMV infection during pregnancy with the index child.

The data are compatible with a congenital infection of CMV leading to increased risk of childhood hematologic malignancies, but not tumors of the central nervous system, although a cautious interpretation is warranted because of the small numbers.