Lymphoma

Lymphomas are a group of malignant tumors (cancers) that develop from lymphatic tissues and specifically from proliferating lymphocytes.  They are of three types, namely Hodgkin’s lymphoma, non-Hodgkin’s lymphoma and Burkitt’s lymphoma (which can also be considered as a type of non-Hodgkin’s lymphoma).  The incidence of lymphoma in the US is about 64, 000 every year, and more than 493, 000 are living with the disease (Leukemia and Lymphoma Society 2006).
Hodgkin’s lymphoma is a unique malignant condition in which the lymphoid tissues present throughout the body are involved (undergo painless enlargement), and is characterized by the presence of certain tumor known as ‘Reed-Sternberg cells’ (Mackie and Ludlam 1996).  The incidence of Hodgkin’s lymphoma in the US is about 7, 500 annually (Portlock and Yahalom 2000).  Non-Hodgkin’s lymphomas are a group of cancerous tumors that arises from the lymphoid tissues and is characterized by the malignant multiplication and growth of the lymphocytes.
The Reed-Sternberg cells are absent.  Non-Hodgkin’s can develop in almost any site of the body such as the lymph nodes, spleen, liver, bone marrow, digestive tract, brain, etc.  70 % of all lymphomas belong to the non-Hodgkin’s variety (Mackie and Ludlam 1996), and about 50, 000 people developed this condition in the US in 1997 (Shipp and Harris 2000).  Burkitt’s lymphoma is an aggressive variant of non-Hodgkin’s lymphoma that arises from the B-lymphocytes.  It is associated with the EB virus, and more often occurs in young children (Mackie and Ludlam 1996).

The exact cause of Lymphomas and the manner in which the disease occurs is still not understood properly.  Several factors including immunodeficiency states (which may be congenital or acquired), infectious diseases, chemical substances (including certain drugs, solvents, pesticides, fertilizers, herbicides, etc), physical agents, autoimmune conditions, etc, may be associated with the disease (Shipp and Harris 2000).  In immune disorders, the body’s defense mechanism is compromised, and persistent antigenic stimulation may result in the development of lymphomas.
In several congenital disorders, such as Wiscott-Alcridge syndrome, common variable immunodeficiency and severe combined immunodeficiency may be related with certain lymphomas.  Several acquired immune disorders such as post-transplant states, AIDS, administration of immunosuppressant, etc, may be associated with lymphomas.  Individuals suffering from various autoimmune disorders such as Hashimoto’s Thyroiditis, Sjogren’s syndrome, lupus, rheumatoid arthritis, etc, may be associated with lymphomas.
Several infectious agents such as H. pylori, EB virus, HTL Virus-1, Hepatitis C virus, Kaposi’s Sarcoma-causing virus (that is linked to the HIV virus) may be associated with the development of lymphomas (Shipp and Harris 2000). Genetic factors also play a very important role ion the development of lymphomas, as the incidence is higher in siblings (than ordinary population) and identical twins (compared to non-identical twins) (Portlock and Yahalom 2000).
The tumor cells present in Hodgkin’s lymphoma is known as ‘Reed-Sternberg cells’ (large in size with 2 nucleus) which may be present in lower numbers compared to other inflammatory cells.  Based on the amount and the manifestations of the Reed-Sternberg cells, Hodgkin’s lymphoma can be classified into 4 types.  As the number of Reed-Sternberg cells increases and the lymphocytes drop, the diseases progresses, spreads to several areas of the body (including the extra-nodal sites) and has a poorer outcome (Portlock and Yahalom 2000).
Various modalities are currently utilized to stop and fight the disease namely, radiotherapy, chemotherapy, bone marrow transplantation, immunotherapy, Angiogenesis Inhibitors, and gene therapy (ehealth MD 2004).  These individual modalities may be required alone or in combination with each other to effectively treat the disease and reduce the adverse-effects.
Chemotherapy is the administration of certain agents (usually utilizing multiple drugs) into the blood that destroys the cancerous cells and reduces their uncontrollable multiplication (Shipp and Harris 2000).  Radiotherapy is administered to the affected site to shrink the size of the tumor by destroying cancerous cells.  Both these therapies may be required in combination with each other (ehealth MD 2004).  Bone marrow transplantations are performed to replace the bone marrow affected with the chemotherapy and replace with healthy tissue that can restore the WBC counts (Mackie and Ludlam 1996).
Immunotherapy is a treatment modality in which certain substances known as ‘cytokines’ are administered which stimulate the white blood cells to capture and destroy the cancerous cells.  Some of the cytokines that are frequently utilized include interferon and interleukin.  Monoclonal antibodies can also be administered that help the body’s defense cells to fight the cancerous cells.  They usually attach themselves to the cancerous cells, which are later identified and destroyed by the white blood cells.
Vaccines are also being manufactured that could prevent infections associated with lymphoma.  Angiogenesis Inhibitors are medications that prevent the formation of new blood vessels in the body.  They can be administered locally in the area of the tumor, such that the blood vessels that feed the tumor are destroyed.  In this way the cancerous cells are deprived of nutrition and may slowly degenerate.  Gene therapy involves correcting the defect in the DNA so that the cancerous cells do not multiply uncontrollably, or certain molecules are attached which cause the cancerous cell to die (ehealth MD 2004).
References:
E-Health MD. Non-Hodgkin’s Lymphoma. [Internet]. 2004 [cited 2007 Apr 16]. Available from: http://www.ehealthmd.com/library/lymphoma/NHL_treatment.html
Mackie, MJ, Ludlam, CA 1996. Diseases of the Blood. Edwards, CRW, Bouchier, IAD, Haslett, C, editors Davidson’s Principles and Practice of Medicine. 17th ed. Edinburgh: Churchill Livingstone. p. 815-821.
Portlock, CS, Yahalon, J 2000. Hodgkin’s Lymphoma. Goldman, L, Bennett, JC, editors Textbook of Medicine. 21st ed. Philadelphia: W.B. Saunders. p. 969-977.
Shipp, MA, Harris NL 2000. Non-Hodgkin’s Lymphomas. Goldman, L, Bennett, JC, editors Textbook of Medicine. 21st ed. Philadelphia: W.B. Saunders. p. 962-969.
The Leukemia and Lymphoma Society. Non-Hodgkin’s Lymphoma. [Internet]. 2007 [cited 2007 Apr 16]. Available from: http://www.leukemia-lymphoma.org/all_page?item_id=7030