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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 childhood Hodgkin lymphoma cancer develops in children who don’t have any of the risk factors described below.
Hodgkin lymphoma can occur in children at any age. However, it rarely occurs 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 these 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 the risk for childhood Hodgkin lymphoma.
Risk factors are generally listed in order from most to least important. In most cases, it is impossible to rank them with absolute certainty.
Known risk factors
There is convincing evidence that the following factors increase the risk for childhood Hodgkin lymphoma.
Previous infection with the Epstein-Barr virus (EBV) is associated 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 of 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 AIDSAIDSA disease caused by the human immunodeficiency virus (HIV) in which lymphocytes (a type of white blood cell that fights germs, foreign substances or cancer cells) are destroyed and the body cannot protect itself from infection. (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 lymphoma.
Wiskott-Aldrich syndrome is an inherited condition that affects blood cells and cells of the immune system. Wiskott-Aldrich syndrome is linked with a hihger risk of bruising, bleeding and infection. It mainly affects boys. Children with Wiskott-Aldrich syndrome have an increased risk of developing lymphoma.
The following factors have been linked with childhood Hodgkin lymphoma, but there is not enough evidence to show they are known risk factors. Further study is needed to clarify the role of these factors for Hodgkin lymphoma in children.
Less exposure to infections
Some studies have suggested that less exposure to infections in early childhood may increase the risk of Hodgkin lymphoma. Children with brothers and sisters, children who go to a daycare and children who live in crowded conditions are more likely to pick up common childhood infections early in life. It is thought that this may help them develop a healthy immune system and reduce the chance of developing Hodgkin lymphoma.
Socioeconomic status may play a role in childhood Hodgkin lymphoma. The incidence of Hodgkin lymphoma is higher in young children with poorer socioeconomic status who live in developing countries. However, the risk for Hodgkin lymphoma among adolescents is higher in wealthier, developed countries. There is also a link between socioeconomic status and the subtype of Hodgkin lymphoma that develops in children and adolescents. The reason for this is not clear.
Unknown risk factors
It isn’t known whether or not the following factors have a relationship with childhood Hodgkin lymphoma. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if the following are risk factors for childhood Hodgkin lymphoma:
- exposure to pesticides
- being breastfed as an infant
Questions to ask your healthcare team
Ask your child’s healthcare team questions about risks.
Support from someone who has ‘been there’
The Canadian Cancer Society’s peer support program is a telephone support service that matches cancer patients and their caregivers with specially trained volunteers.