Lymphoma is a malignant
blood disorder that affects mainly the lymphatic system. The cancer occurs when certain lymphocytes (type of
white blood cells that play major roles in defending the body against microorganisms…) start growing
abnormally and uncontrollably due to certain carcinogenic factors. Gradually, these cells accumulate and end
up creating an uncontrolled proliferation of tumor called lymphoma.
Like most cancers,
treatment for lymphoma includes chemotherapy and radiotherapy. And in recent years, there are new targeted
therapies prescribed only in case of relapse, if other treatments have not worked. For additional info,
please see lymphoma treatment.
The World Health
Organization (WHO) has identified 80 types of lymphoma, which are classified into two main categories, of
different gravity and evolution: Hodgkin lymphoma, also called Hodgkin's disease, represents less than one in
7 of lymphomas; and non-Hodgkin lymphoma (NHL), which is most common, affects preferentially men. Lymphoma
symptoms can differ from one type to another.
NHLs are malignancies
which usually occur within the lymphoid tissues: lymph nodes, spleen, bone marrow. They can also occur in
extranodal locations such as the gastrointestinal tract (stomach, small intestine), oral cavity and pharynx,
skin, central nervous system, testes. Their frequency increase over time, which makes scientists believe the
role of environmental factors (agricultural pesticides for instance) in its development. Non-Hodgkin lymphoma
treatment therefore depends on the extent of the disease and the general health status of the patient. The
number of new cases has increased nearly 5% per year in recent decades.
Hodgkin lymphoma, also
known as Hodgkin's disease, is another form of lymphatic cancer characterized by abnormal proliferation of a
certain type of white blood cells called lymphocytes and the presence of particular abnormal cells known as
Sternberg cells. This is what differentiates Hodgkin lymphoma of all other lymphomas that are given the
generic name of "non-Hodgkin lymphoma." When it comes to Hodgkin's lymphoma symptoms, the proliferation of
abnormal cells causes an increase in the lymph nodes, which makes them unable to function properly. The
organism therefore loses part of its defense system against viruses and bacteria, and therefore infections
occur more easily.
The lymphatic system
includes the lymph vessels, lymph nodes and lymph. It has many functions of which the main ones are the
regulation of the immune cells throughout the body and activation of the immune system response during
pathogenic attacks such as infection. It also contributes to the circulation of hormones and nutrients, and
allows drainage of excess fluid in the tissues.
The lymphatic vessels
compose of all the vessels that circulate lymph, a biological fluid comparable to blood containing white
blood cells, but devoid of red blood cells. This is the reason the ancient Greeks had called it "white
blood". Human has an average of one to two liters of lymph, less than blood which is five to six liters. The
lymphatic vessels are present throughout the body except in the central nervous system, muscles, cartilage,
and bone marrow. The circulation of the lymph is assured with no muscular pump, unlike blood circulation
which is possible thanks to the pumping of the heart. These are body movements, such as muscle contractions
and the walls of the fibers of the lymphatic vessels, that allow the circulation of lymph.
Some of the lymphatic
system organs include lymph nodes, thymus, and spleen. The lymphocytes develop in the primary lymphoid organs
such as bone marrow and thymus, for T lymphocytes. Once produced, they can colonize the lymphatic network and
secondary lymphoid organs: lymph nodes, spleen, and lymphoid tissue associated with mucous membranes.
Therein, lymphocytes proliferate and differentiate to target each specific antigen.
Therefore, lymphoma is
not a cancer that develops in a specific organ such as breast cancer or lung cancer. But it grows throughout
the organs of the lymphatic system: spleen, thymus, bone marrow, as well as the lymph nodes, and the vascular
system which assures circulation of blood and lymph through the body. For additional info, please see
General Information About Adult Hodgkin Lymphoma". National Cancer Institute. 2014-04-23. Retrieved
Aditya Bardia (2010). Johns Hopkins Patients' Guide to Lymphoma.
Jones & Bartlett Learning. p. 6. ISBN 9781449631413.
“Hodgkin Lymphoma—SEER Stat Fact Sheets".
Seer.cancer.gov. Retrieved 2012-08-26.
“Non-Hodgkin Lymphoma - SEER Stat Fact Sheets ". NCI. Retrieved 18 June 2014
Warning Signs of Lymphoma — First Signs of Lymphoma". Lymphoma.about.com. Retrieved 07-08-2015
National Cancer Institute, "Hodgkin Lymphoma", http://www.cancer.gov/cancertopics/types/hodgkin, Retrieved 07-08-2015
General Information About Adult Non-Hodgkin Lymphoma". National Cancer Institute. 2014-04-25. Retrieved