A risk factor  is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do.
Although the exact cause of NHL is unknown, some children seem to have a slightly higher risk of developing the disease:
- Those who have had illnesses related to the Epstein-Barr virus (for example, infectious mononucleosis)
- Those who have acquired immune deficiency syndrome (AIDS)
- Children who have received an organ transplantation
- Children born with deficiencies in their immune systems
- Children who have been treated with certain drugs for other types of cancer
Rarely, children who take phenytoin (Dilantin), a drug used to control seizures