Lymphomas constitute a group of cancers that affect the lymphatic system, which contributes to the defence of the organism. They represent the 6th most frequent cancer type in the world, with an estimated total of 2 million patients affected.
Lymphomas are classified as malignant blood diseases, i.e. cancers that develop from cells circulating in the blood. They present the particularity of affecting lymphocytes, which are cells from the white blood cell family circulating in the blood and lymphatic system to ensure the defence of the organism.
The lymphatic system is a key element of the immune system in its fight against pathogenic agents. This system includes:
- a network of lymphatic vessels that transport lymphocytes in a transparent liquid, called lymph;
- lymph nodes and organs where the lymphocytes are produced and/or present in large quantities: spleen, tonsils, thymus, lymphoid tissues associated with the mucous membranes (intestines, lungs etc.), bone marrow.
A lymphoma can develop from one or two large lymphocyte families: B or T lymphocytes. It is a complex disease, including no less than 80 sub-types according to the classification of the World Health Organisation. The clinical evolution and care are different depending on the lymphoma sub-type.
What are the symptoms?
Identifying a lymphoma is not easy. It is often the patient’s doctor who considers it due to the symptoms described, or on the basis of the data from their clinical investigation or other investigations (blood samples, x-ray or ultrasound, for example).
The most frequently observed telling clinical sign is the development of a lump on one or more of the lymph nodes (neck, armpits, groin) or an organ. Other symptoms may sometimes be observed: weight loss, fever, perspiration or heavy fatigue.
What are the causes?
As for most tumours, the exact cause of lymphomas is not known. Certain factors of risk are suspected however (immunodepression, infection, environmental factors).
We know that people with weakened immune defences (after a treatment or various illnesses) are more at risk of developing lymphomas. Certain viruses can favour the appearance of this cancer, but it is in no way a contagious disease.
Environmental factors (dioxins, pesticides…) are also suggested as possible causes of the rapid increase of lymphoma occurrences since the 70s. It is one of the tumours of which the occurrence has increased the most in the period between the 1970s and 1990s.
The number of new lymphoma cases diagnosed each year is estimated to amount to 110,000 in Europe, 83,000 in the United States and 14,000 in France. Lymphomas represent the most frequent malignant blood disease in metropolitan France, at approximately half of all blood cancers.