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Risk factors for childhood non-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 non-Hodgkin lymphoma (NHL) develops in children who don’t have any of the risk factors described below.
The following are risk factors for childhood NHL. All 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 the 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.
There is convincing evidence that the following factors increase the risk for childhood NHL.
Your immune system is a complex group of cells and organs that defend the body against infection, disease and foreign substances. Children with a weakened immune system have a higher risk of developing NHL. The immune system can be weakened for a number of reasons.
Immunosuppressant drugs affect the immune system so that it doesn’t respond as it normally would. These drugs are used to prevent a child’s immune system from attacking a new organ after a transplant. But immunosuppressant drugs also lower the body’s natural ability to defend itself. Children who have had an organ transplant and are taking immunosuppressant drugs have a higher risk of developing NHL.
HIV (human immunodeficiency virus) and AIDS (acquired immunodeficiency syndrome) weaken the immune system. Children with HIV or AIDS have a greater risk of developing childhood NHL.
Certain genetic immunodeficiency syndromes also affect the immune system:
- Ataxia-telangiectasia (AT) affects the nervous system, immune system and other body systems. Children with AT have problems with walking, balance, hand coordination and nerve function. They often have a weakened immune system and have a higher risk of developing some cancers, including NHL.
- Wiskott-Aldrich syndrome affects blood cells and cells of the immune system. Children with Wiskott-Aldrich syndrome have lower numbers of platelets, which means they can bruise and bleed easily. They also have a higher risk for infection because their immune cells (such as T cells and B cells) don’t work properly. Children with Wiskott-Aldrich syndrome also have a higher risk of developing some types of cancer, such as NHL.
- X-linked lymphoproliferative syndrome affects the immune system so it doesn’t respond the way it normally would to infection with the Epstein-Barr virus. Children with X-linked lymphoproliferative syndrome have a higher risk of developing NHL.
- Chediak-Higashi syndrome affects both the immune and nervous systems. Children with Chediak-Higashi syndrome have a higher risk of developing certain cancers of the immune system, such as NHL.
- Severe combined immunodeficiency disorder (SCID) severely weakens the immune system. When children have SCID, their T cells and B cells don’t work normally. They have a high risk of developing serious infections and certain types of cancer, such as NHL.
Epstein-Barr virus (EBV) is a type of herpes virus that causes infectious mononucleosis (also called mono, or the kissing disease).
Children with EBV infection have a higher risk of developing Burkitt lymphoma, a type of B-cell lymphoma. This type of childhood NHL is most often found in Africa, where children may also be infected with malaria. In Canada, EBV is usually linked to NHL in children who have weakened immune systems.
The following factors have been linked with childhood NHL, 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 NHL.
- exposure to pesticides
- exposure to cigarette smoke before birth
Questions to ask your healthcare team
Ask your child’s healthcare team questions about risks.
Making progress in the cancer fight
The 5-year cancer survival rate has increased from 25% in the 1940s to 60% today.