Risk factors for childhood Hodgkin lymphoma

A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. But sometimes Hodgkin lymphoma develops in children who don’t have any of the risk factors described below.

Hodgkin lymphoma can occur in children at any age, but it is rarely found in children younger than 5 years of age. Hodgkin lymphoma is more common in teenagers and younger adults. It usually develops in people who are in their mid-teens (typically around age 15) to their 30s.

If Hodgkin lymphoma develops in children younger than 5 years of age, it is more likely to develop in boys than in girls. In teenagers, boys and girls seem to be affected fairly equally.

The following are risk factors for childhood Hodgkin lymphoma. Most of the risk factors are not modifiable. This means that you can’t change them. Until we learn more about these risk factors, there are no specific ways you can reduce your risk.

Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.

Epstein-Barr virus (EBV) infection

Family history

Weakened immune system

There is convincing evidence that the following factors increase the risk for childhood Hodgkin lymphoma.

Infection with the Epstein-Barr virus (EBV) is linked with Hodgkin lymphoma in both children and adults. EBV infection at an early age may play a role in the development of Hodgkin lymphoma in children.

EBV is a type of herpes virus (Human herpesvirus 4 or HHV-4). It causes infectious mononucleosis, which is also called mono or the “kissing disease.” Mononucleosis is a highly infectious disease that causes fever, fatigue, malaise and sore throat.

EBV has been found in tumour cells of some children with Hodgkin lymphoma. Some subtypes of Hodgkin lymphoma are more likely to be linked to EBV than others.

Having a brother or sister with Hodgkin lymphoma increases a child’s risk of developing this cancer. The risk is very high for an identical twin of a child with Hodgkin lymphoma. Having a parent with Hodgkin lymphoma can also increase a child’s risk, but not as much as having a sibling with the disease.

While family history increases the risk for Hodgkin lymphoma, it accounts for only a small percentage of all cases of the disease. It is not clear why family history might increase risk. The increased risk may be due to inherited faulty genes, similar environmental or infectious exposures or a combination of these factors.

Children with a weakened immune system have a higher risk of developing Hodgkin lymphoma. A child’s immune system can be weakened by:

• HIV (human immunodeficiency virus) or AIDS (acquired immunodeficiency syndrome)
• drugs that suppress the immune system (immunosuppressant drugs) such as those taken after an organ transplant to help prevent rejection of the organ
• an immunodeficiency disorder such as ataxia-telangiectasia and Wiskott-Aldrich syndrome

Ataxia-telangiectasia is a rare genetic condition that affects the nervous system, immune system and other body systems. Children born with ataxia-telangiectasia have a higher risk of developing certain cancers, such as lymphoma and leukemia.

Wiskott-Aldrich syndrome is an inherited condition that affects blood cells and cells of the immune system. Wiskott-Aldrich syndrome is linked with a higher risk of bruising, bleeding and infection. It mainly affects boys. Children with Wiskott-Aldrich syndrome have a higher risk of developing certain cancers, such as lymphoma and leukemia.

The following factors have been linked with childhood Hodgkin lymphoma, but there is not enough evidence to show for sure that they are risk factors. More research is needed to clarify the role of these factors for childhood Hodgkin lymphoma.

• less exposure to infections
• socioeconomic status

Ask your child’s healthcare team questions about risks.