Non-Hodgkin lymphoma ( NHL) is a cancer that arises from the lymphatic system, a part of the immune system which consists of lymph nodes and lymph vessels. Although risk factors for NHL generally relate to impaired immune function, the causes of most lymphomas are not clear. In Colorado, the cumulative lifetime risk of NHL is one in 34 for males and one in 47 for females. In contrast to a type of lymphoma known as Hodgkin's Lymphoma, NHL is more difficult to treat and has lower survival rates. For 2000-2003, the five-year survival for NHL was about 65%, with lower survival for Hispanics and blacks observed in this time period.