Lymphoma is a term for various, usually malignant, tumors that arise in the lymph nodes or in other lymphoid tissue. Malignant tumors are cancerous, and metastasize (spread), while benign tumors do not metastasize. Lymphoma encompasses more than 40 related types of cancer that develop from lymphocytes (cells of the immune system). Lymphoma occurs when one of these cells undergoes a transformation into a malignant cell and begins to grow abnormally dividing and forming tumors. The distinctions between types of lymphoma are based on the different characteristics of the cancerous cells.
Lymphoma that is slow-growing is also called low grade or indolent; fast-growing lymphoma is called high-grade or aggressive.
Major risk factors include age (most common in individuals in their 60s), immune system status (lowered immunity may lead to lymphoma development), and a family history of lymphoma (genetics may play a large role in who develops lymphoma).
There are over one million people around the world living with lymphoma. It is estimated that approximately 350,000 new cases of lymphoma are diagnosed worldwide annually.
Leukemia, lymphoma/myeloma, accounts for 8.7% of all cancers diagnosed each year in the United States.
Each day approximately 170 Americans are diagnosed with lymphoma.
The two main types or groups of lymphoma in humans are Hodgkin's disease (or Hodgkin's lymphoma) and the non-Hodgkin's lymphomas (NHLs). They both produce similar symptoms and differentiation between the two is done using microscopic evaluation of the cancer cells. There are five subtypes of Hodgkin's disease and about 30 subtypes of non-Hodgkin's lymphoma.
Approximately 60,000 Americans are diagnosed with NHLs in the United States annually, and about 7,000 are diagnosed with Hodgkin's disease. Hodgkin's disease accounts for only one percent of all cancers in the United States, while NHLs represent four percent of all cancers.
Survival rates for Hodgkin's lymphoma are 83% at five years, 74% at ten years, and 66% at 15 years. For non-Hodgkin's, the rates of survival are 53% at five years, 43% at ten years, and 37% at 15 years. These numbers depend upon the individual.
The prognosis for lymphomas also depends largely on the type of lymphoma and the grade of lymphoma with which the individual has been diagnosed.
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The lymphatic system is an organization of lymph nodes, lymph vessels, and lymph nodules along with lymphoid tissue (including the thymus, spleen, tonsils, and bone marrow) through which lymph circulates and is filtered. Lymph is the clear, colorless fluid that circulates through the lymphatic system. Lymph nodes are small, rounded masses of lymphoid tissue contained in connective tissue (including bone, cartilage, adipose or fat, and collagen). Lymph nodes are found along lymphatic vessels with clusters in certain areas, such as the neck, groin, and armpits.
The lymphatic system performs several functions in the body. It drains fluid back into the bloodstream from the tissues, filters lymph, filters the blood, and fights infections. As the blood circulates, fluid leaks out into the body tissues. This fluid is important because it carries food to the cells and waste products back to the bloodstream. The leaked fluid drains into the lymph vessels. It is carried through the lymph vessels to the base of the neck where it is emptied back into the bloodstream. This circulation of fluid through the body goes on all of the time. The lymph nodes filter the lymph as it passes through. White blood cells attack any bacteria or viruses they find in the lymph as it flows through the lymph nodes. If cancer cells break away from a tumor, they often become lodged or "stuck" in the nearest lymph nodes. This is the reason doctors check the lymph nodes first when they are working out how far a cancer has grown or spread.
The spleen is a lymphatic organ that filters the blood removing all of the old worn out red blood cells and destroying them. They are replaced by new red blood cells that have been made in the bone marrow. The spleen also filters out bacteria, viruses, and other foreign particles found in the blood. White blood cells in the spleen attack bacteria and viruses as they pass through. The lymphatic system helps fight infection in many ways, such as helping to make white blood cells (lymphocytes) that produce antibodies. Antibodies are the part of the immune system that attacks specific foreign particles, such as viruses and bacteria, in the body. Macrophages, immune cells found inside the lymph nodes, engulf (swallow up) and destroy foreign particles.
A lymphocyte is a type of white blood cell involved in the immune system. There are two categories of lymphocytes, namely the large granular (composed of large particles) lymphocytes and the small lymphocytes. The large granular lymphocytes are more commonly known as the natural killer cells (NK cells). The small lymphocytes are the T-cells and B-cells. B-cells produce antibodies. T-cells, when activated, can kill pathogens (disease causing agents) directly. T-cells also play a part in controlling the immune system, preventing the system from inappropriate overactivity or underactivity. After encountering a pathogen (such as a virus or bacteria), B and T cells "remember" the foreign material and are prepared to fight it off if it returns. This is called cellular immunity.
Cancer can develop in the lymph nodes in two ways. It can either start there as a primary cancer, or it can spread into the lymph nodes from a primary cancer elsewhere in the body. If cancer spreads into the lymph nodes from another part of the body, this is known as secondary
metastatic cancer. Cancer that starts in the lymph nodes is called lymphoma.
In lymphomas, malignant (cancerous) lymph cells proliferate (multiply), causing lymph node enlargement. Other cancers, such as breast, colon, liver, prostate, and stomach, often invade lymphatic vessels, which can carry cells from the tumor to lymph nodes, where they are trapped and grow into secondary tumors. When other cancers metastasize (spread), lymph nodes are usually involved. Lymph nodes are therefore removed in cancer surgery to detect or prevent tumor spread.
types of lymphoma
Hodgkin's disease or Hodgkin's lymphoma
Hodgkin's disease was named after the doctor who first recognized it in 1832, Thomas Hodgkin. If diagnosed early, 75-95% of individuals may be cured.
Hodgkin's disease is characterized by the growth of Reed-Sternberg cells in the cancer. Reed-Sternberg cells are distinctive giant cells found in individuals with Hodgkin's lymphoma. They can also be found in reactive lymphadenopathy (such as infectious mononucleosis, carbamazepine associated lymphadenopathy) and rarely non-Hodgkin lymphomas. Men typically have higher incidences of Hodgkin's disease (HD) than women. HD is more common in Caucasians than in African Americans, Latinos, or Asians. HD affects both adults and children, although it is most common in two age groups: young adults (in their late teens) and older adults (ages 60 and older). The age differences are more apparent in women, and may be related to the changes in hormones that take place during puberty and menopause. Only about 10-15% of HD cases occur in children who are younger than 16 years of age.
Nearly 90% of NHLs are B-cell lymphomas. There are 14 types of B-cell lymphomas. The other types of non-Hodgkin lymphomas are T-cell and natural killer (NK) cell lymphomas and immunodeficiency-associated lymphoproliferative disorders (caused by viruses such as Epstein-Barr and human immunodeficiency virus or HIV).
Diffuse large B-cell lymphoma, a fast-growing lymphoma, and follicular lymphoma, a slow-growing lymphoma, are the two most common B-cell lymphomas. Together, these two types make up more than half of all non-Hodgkin lymphomas.
B-cell neoplasms (tumors) are divided into two groups, including precursor and mature B-cell neoplasms. An example of a precursor B-cell neoplasm includes precursor B-lymphoblastic leukemia/lymphoma. Mature B-cell neoplasms include B-cell chronic lymphocytic leukemia or small lymphocytic lymphoma, B-cell prolymphocytic leukemia, lymphoplasmacytic lymphoma, splenic marginal zone B-cell lymphoma, nodal marginal zone lymphoma, extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type, hairy cell leukemia, plasma cell myeloma/plasmacytoma, follicular lymphoma, mantle cell lymphoma, diffuse large cell B-cell lymphoma, mediastinal large B-cell lymphoma, intravascular large B-cell lymphoma, primary effusion lymphoma, and Burkitt's lymphoma/Burkitt's cell leukemia.
T-cell and natural killer (NK) cell neoplasms include precursor T-cell neoplasm (tumor) and mature T-cell and NK-cell neoplasms. Precursor T-cell neoplasms include t-lymphoblastic lymphoma/leukemia and blastic NK lymphoma. Mature T-cell and NK-cell neoplasms include T-cell prolymphocytic leukemia, T-cell granular lymphocytic leukemia, aggressive NK-cell leukemia, adult T-cell lymphoma/leukemia (HTLV1+), extranodal NK/T-cell lymphoma (nasal type), enteropathy-type T-cell lymphoma, hepatosplenic gamma-delta T-cell lymphoma, subcutaneous panniculitis-like T-cell lymphoma, mycosis fungoides/Sézary's syndrome, primary cutaneous anaplastic large cell lymphoma, T/null cell, peripheral T-cell lymphoma (unspecified), angioimmunoblastic T-cell lymphoma, and primary systemic anaplastic large cell lymphoma, T/null cell.
Sometimes NHLs are described by their location in the body, including central nervous system (CNS, brain and spinal cord) lymphoma, lymphoma of bone, eyelid lymphoma, digestive tract lymphoma, and ocular (eye) lymphoma.
NHLs are the most common cancer of the lymphatic system and the fifth most common cancer in the United States. The incidence of NHLs has grown by 80% since the early 1970's.
The majority of NHLs (95%) occur in adults 40-70 years of age. However, some NHL subtypes are among the most common cancers in children. More men than women develop NHLs and rates are particularly high among men who live in locations with a high rate of human immunodeficiency virus (HIV) infection, such as the San Francisco/Oakland area. Individuals with HIV have impaired immune systems, and may be more susceptible to diseases such as cancer (lymphoma and others). NHLs are more common in Caucasians than in Latino, African Americans, and Asians.