A risk factor is any factor that can increase the person’s risk of developing that condition, in this case, non-Hodgkin lymphoma. Having one or more risk factors does not mean that you will develop cancer. It can also be unclear whether a risk factor contributed to the development of the cancer in a person. The known risk factors for prostate cancer are: Increasing age Exposure to certain chemicals such as pesticides and some chemotherapies Weakened immune system – such as a result of infections (e.g. HIV) or medicines that suppress the immune systemInfection with certain viruses such as HIV, Epstein-Barr virus and chronic infections