Breastfeeding and Childhood Cancer

“Breastfeeding and Childhood Cancer: Insights from Denmark’s Massive Study”

A large-scale analysis conducted in Denmark, involving over 300,000 children, revealed that exclusive breastfeeding for a minimum of three months is associated with a reduced risk of hematological diseases, especially acute lymphoblastic leukemia. At the same time, this type of feeding did not affect the risk of developing tumors in the central nervous system or solid tumors. The study results were published in the JAMA Network Open journal.

Some studies, including extensive data analyses, have shown that among children who were breastfed for at least six months, the risk of developing acute lymphoblastic leukemia was reduced by approximately 20% compared to those who were breastfed for a shorter period or not at all. Additionally, other studies have shown that breastfeeding reduces the risk of developing acute myeloid leukemia, Hodgkin lymphoma, and neuroblastoma.

This beneficial effect of breastfeeding has a documented biological basis, as breast milk plays a crucial role in shaping the internal environment of the intestines and the child’s immune system. According to this, it is believed that abnormal immune responses to aggressive stimuli significantly affect the development of B-cell precursors, which are often the morphological basis of acute lymphoblastic leukemia. Furthermore, studies using mouse models have directly linked the gut environment to the formation of this type of tumor. However, it remains unclear to what extent the duration of breastfeeding can be considered ideal for tumor prevention.

A team of scientists led by Søren Holst Søegaard from the Danish Cancer Institute conducted a population-based study including 309,473 children born in Denmark between 2005 and 2018. Information on the duration of breastfeeding was available for all children. Over a total of 1,679,635 person-years of follow-up, cancerous tumors were diagnosed in 332 children (with a median age at diagnosis of 4.24 years): 124 children had hematological malignancies, 44 had tumors in the central nervous system, 80 had solid tumors, and 84 had other malignant tumors.

Among children diagnosed with hematological malignancies, there were 81 cases of acute lymphoblastic leukemia, of which 74 had B-cell precursor subtypes. Seven other children were diagnosed with acute myeloid leukemia, and the remainder were diagnosed with Hodgkin lymphoma. The most common tumors diagnosed in the central nervous system were astrocytomas and ependymomas, as well as embryonal tumors inside the skull and spinal column. The most common solid tumors were kidney tumors, neuroblastomas, and soft tissue tumors.

The relative risk ratio for developing hematological malignancies was 0.91 and 0.90 after linear-logarithmic adjustment for comparison between children who received breastfeeding and those who did not. In the analysis comparing shorter exclusive breastfeeding periods with feeding for three months, it was found that longer breastfeeding was associated with a reduced risk of developing hematological diseases (relative risk ratio of 0.66), with a greater reduction in the risk of developing acute lymphoblastic leukemia. At the same time, the risk of developing tumors in the central nervous system, solid tumors, and neuroblastoma did not depend solely on the duration of breastfeeding. These study results confirm previous conclusions regarding the preventive efficacy of breastfeeding regarding hematological diseases. However, scientists in this study discovered that even three months of exclusive breastfeeding carries this effectiveness, and it is expected that doctors will determine the preventive impact for each month of breastfeeding in the future.