Lymphoma is a cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin lymphomas can be further divided into cancers that have an indolent (slow-growing) course and those that have an aggressive (fast-growing) course. These subtypes behave and respond to treatment differently. Both Hodgkin and non-Hodgkin lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer.
Lymphoma, including Hodgkin lymphoma and non-Hodgkin lymphoma (NHL), represents approximately 5 percent of all cancers in the United States. Nearly 70,000 new cases of NHL and 9,300 new cases of Hodgkin lymphoma are estimated for 2013.
Due to improvements in treatment, mortality for Hodgkin lymphoma has decreased by nearly 50 percent over the past 25 years. Over the same period, incidence has remained relatively steady.
Although the rate of increase has slowed in the past two decades, NHL incidence has climbed steadily since 1975. NHL mortality has declined since 1997. Incidence and mortality for NHL are higher for whites than for African Americans or people of other racial/ethnic groups in the United States.
Risk factors for both Hodgkin lymphoma and NHL include having a weakened immune system or being infected with human immunodeficiency virus (HIV) or Epstein-Barr virus. Infection with Helicobacter pylori or human T-cell leukemia/lymphoma virus type 1 (HTLV-1) increases the risk for certain types of NHL. The risk of NHL increases with age, whereas the risk of Hodgkin lymphoma is higher in both early adulthood and later life. Standard treatments for both types of lymphoma are chemotherapy, radiation therapy, and watchful waiting. Additional standard therapies include surgery for Hodgkin lymphoma and targeted therapy, plasmapheresis, and biological therapy for NHL.