Lymphoma is cancer that begins in infection-fighting cells of the immune system, called lymphocytes. These cells are in the lymph nodes, spleen, thymus, bone marrow, and other parts of the body. When you have lymphoma, lymphocytes change and grow out of control. Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Risk factors that a... Read the Risk Factors article > > Non-Hodgkin: Most people with lymphoma have this type. Every type of lymphoma grows at a different rate and responds differently to treatment. Your doctor can help you find the right treatment for your type of the illness.