Non-Hodgkin lymphoma (NHL) is a group of blood cancers that includes all types of lymphoma except Hodgkin's lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss and tiredness. Other symptoms may include bone pain, chest pain or itchiness. Some forms are slow-growing, while others are fast-growing.Lymphomas are types of cancer that develop from lymphocytes, a type of white blood cell. Risk factors include poor immune function, autoimmune diseases, Helicobacter pylori infection, hepatitis C, obesity and Epstein-Barr virus infection. The World Health Organization (WHO) classifies lymphomas into five major groups, including one for Hodgkin's lymphoma. Within the four groups for NHL, there are over 60 specific types of lymphoma. Diagnosis is by examination of a bone marrow or lymph node biopsy. Medical imaging is done to help with cancer staging.Treatment depends on whether the lymphoma is slow- or fast-growing and if it is in one area or many areas. Treatments may include chemotherapy, radiation, immunotherapy, targeted therapy, stem cell transplantation, surgery or watchful waiting. If the blood becomes overly thick due to high numbers of antibodies, plasmapheresis may be used. Radiation and some chemotherapy, however, increase the risk of other cancers, heart disease or nerve problems over the subsequent decades.In 2015, about 4.3 million people had non-Hodgkin lymphoma, and 231,400 died. In the United States, 2.1% of people are affected at some point in their life. The most common age of diagnosis is between 65 and 75 years old. The five-year survival rate in the United States is 71%.