Longer exclusive breastfeeding may lower hematologic cancer risk for children

Key takeaways:

• Exclusive breastfeeding for at least 3 months was linked to reduced risk for childhood hematologic cancers.
• Breastfeeding was not tied to central nervous system tumor, solid tumor or neuroblastoma risks.

Exclusive breastfeeding for at least 3 months was associated with reduced childhood hematologic cancer risk vs. shorter breastfeeding durations, according to cohort study results published in JAMA Network Open.

“The suggested protective effect of breastfeeding against childhood cancer is noteworthy. It not only points to potential biologic pathways that could modulate childhood cancer risk, but also suggests a simple preventive measure,” Signe Holst Søegaard, PhD, postdoctoral researcher at the Danish Cancer Institute and the department of epidemiology research at Statens Serum Institut, Copenhagen, Denmark, and colleagues wrote. “It is therefore crucial to revisit and corroborate previous observations of reduced childhood cancer risk in breastfed children, as existing evidence stems from case-control studies, which are inherently vulnerable to recall and selection biases.”

Søegaard and colleagues conducted a population-based cohort study evaluating data from 309,473 children (51.3% boys) from the Danish National Child Health Register who were born from 2005 to 2018. All children had information on exclusive breastfeeding and were followed from age 1 year until childhood cancer diagnosis, loss to follow-up or emigration, death, age 15 years or December 2020.

Primary outcome was associations between exclusive breastfeeding duration and risk for childhood cancer overall and by subtypes.

During 1,679,635 person-years of follow-up, 0.1% of children were diagnosed with cancer (mean age at diagnosis, 4.24 years). Of children with cancer, 37.3% were diagnosed with hematologic cancers, 13.3% with central nervous system tumors, 24.1% with solid tumors and 25.3% with other and unspecified malignant neoplasms. Of those with hematologic cancers, 65.3% had acute lymphoblastic leukemia of whom 91.4% had B-cell precursor acute lymphoblastic leukemia.

Overall, 38.3% of children diagnosed with cancer were exclusively breastfed for less than 3 months.

Exclusive breastfeeding for 3 months or longer was associated with a decreased risk for hematologic cancers for children compared with shorter durations of exclusive breastfeeding (adjusted HR = 0.66; 95% CI, 0.46-0.95). According to the researchers, this association was largely attributable to decreased B-cell precursor acute lymphoblastic leukemia risk (aHR = 0.62; 95% CI, 0.39-0.99). Central nervous system tumor (aHR = 0.96; 95% CI, 0.51-1.88), solid tumor (aHR = 0.87; 95% CI, 0.55-1.41) or neuroblastoma (aHR = 0.98; 95% CI, 0.32-3.06) risks did not vary by duration of exclusive breastfeeding.

“To inform future preemptive interventions, additional studies should investigate the biologic mechanisms underlying the observed association,” the researchers wrote.