What is a lymphoma?

Almost half of blood cancers are lymphomas. Their causes remain unknown in the vast majority of cases. They are neither hereditary nor contagious. Lymphoma is a cancer that affects the lymphatic system, an essential element of our immune system. The lymphatic system includes lymph nodes, spleen, bone marrow, and other lymphoid tissues. Its main function is to fight infections and contribute to the body's immune defense. 

Lymphomas occur when lymphoid cells, called lymphocytes, grow abnormally. These abnormal cells multiply uncontrollably and form "masses" - or tumors. These can develop in the lymph nodes or other organs, such as the stomach, lung, skin, brain, or bone marrow. 

There are two main types of lymphomas - in 20% of cases, they are Hodgkin's lymphomas (LH), affecting young adults, and for 80% they are non-Hodgkin's lymphomas (NHL), more common in older adults over the age of 60. Some non-Hodgkin's lymphomas have a very slow progression, and they are believed to be indolent. Others are more aggressive. The treatment of such lymphomas is therefore very different.

The case of chronic lymphocytic leukemia (CLL)

Chronic lymphocytic leukemia (CLL) is a particular indolent blood disease, also called lymphocytic lymphoma when it occurs in the lymph node. This disease, although less serious and very different from other so-called "acute" leukemias, is also characterized by an excessive proliferation of abnormal mature B lymphocytes. Since it is chronic, it develops very slowly and over the course of many years. No predisposing factors to CLL have been proven. It is not a hereditary disease, although very rare family forms have been observed.

The INCa estimated nearly 4,700 cases of CLL diagnosed in France in 2018, in patients aged about 72 years.