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Lymphoma, group of cancers that arise in the lymphatic system, body tissues that fight infection and perform several other vital functions in the body. Lymphoma is often called non-Hodgkin’s lymphoma to distinguish it from Hodgkin’s disease, a specific type of cancer that also affects the lymphatic system. However, the term non-Hodgkin’s lymphoma is somewhat misleading because, unlike Hodgkin’s disease, lymphoma encompasses many cancers. These various types of lymphoma differ from each other in symptoms, treatment, and prognosis, depending on the type of cell that becomes cancerous and other characteristics. According to the American Cancer Society, in 2001 more than 56,000 people in the United States developed lymphoma and 26,300 died of the disease. For reasons scientists do not completely understand, the number of people diagnosed with lymphoma has increased more than 80 percent since the early 1970s. The incidence of lymphoma increases with age, and it is slightly more prevalent among men than among women. In the United States, non-Hispanic whites have the highest incidence of lymphoma.
CAUSE
The lymphatic system consists of white blood cells known as T and B lymphocytes; lymphatic vessels, thin tubes that form a network in the body alongside blood vessels; and hundreds of lymph nodes, bean-sized collections of tissue found in the chest, abdomen, neck, groin, and under the arms. Lymphoma occurs when, for mostly unknown reasons, a single B lymphocyte or T lymphocyte becomes cancerous and begins to grow in an unchecked fashion, its descendants eventually spreading throughout the body and crowding out normal tissues. One type of B cell lymphoma is Burkitt’s lymphoma, which typically spreads to areas outside the lymphatic system such as the bone marrow, blood, and central nervous system. Examples of T cell lymphomas include lymphoblastic lymphoma, which usually develops in the thymus and forms a tumor mass in the area behind the chest bone, and mycosis fungoides, a rare skin disorder that spreads to the lymph nodes and internal organs.
People have an increased risk of developing lymphoma if their immune system is weakened due to, for example, a genetic condition, infection with the human immunodeficiency virus (HIV), or as a result of taking immune-suppressing drugs to prevent rejection of a transplanted organ. The connection between immune deficiency and lymphoma leads some scientists to believe that an abnormal immune response to common infections may play a key role in the development of the disease. In Africa, people who are infected with both the malaria parasite and Epstein-Barr virus have an increased risk of developing Burkitt’s lymphoma. However, most people who develop lymphoma have no known risk factors.
People have an increased risk of developing lymphoma if their immune system is weakened due to, for example, a genetic condition, infection with the human immunodeficiency virus (HIV), or as a result of taking immune-suppressing drugs to prevent rejection of a transplanted organ. The connection between immune deficiency and lymphoma leads some scientists to believe that an abnormal immune response to common infections may play a key role in the development of the disease. In Africa, people who are infected with both the malaria parasite and Epstein-Barr virus have an increased risk of developing Burkitt’s lymphoma. However, most people who develop lymphoma have no known risk factors.
SYMPTOMS AND DIAGNOSIS
Computed Tomography Scan A computed tomography (CT) scan produces a cross-sectional image of a portion of the body. A precisely directed, narrow X-ray beam passing through the body provides a highly accurate, painless, diagnostic tool that allows examination of the interior of the body without invasive procedures. This technique helps physicians determine how far lymphoma has spread through the body.Photo Researchers, Inc./Hank Morgan/Science Source
The symptoms of lymphoma vary greatly from person to person, but most frequently the first symptom is a painless swelling of a lymph node in the neck, under an arm, or in the groin. Other symptoms of lymphoma can include shortness of breath; a dry, persistent cough; and pain from masses of tumor cells in various parts of the body, such as the chest or abdomen. Organs, such as the kidneys or liver, may stop functioning properly if lymphoma cells grow into tumors there. Some patients also develop fever, night sweats, or weight loss.
Many of the symptoms of lymphoma may be confused with other common illnesses. For instance, an enlarged lymph node is also a symptom of flu or other common infections, particularly in infants and children. To make a certain diagnosis, doctors perform a biopsy, in which part or all of an enlarged lymph node is removed and examined under a microscope. If cancerous cells are present, doctors also try to establish what type of lymphoma is present and how rapidly it grows. Doctors stage the cancer, or determine how far it has spread, by performing tests, such as computed tomography (CT) scans of the chest and abdomen, blood tests, and biopsies of the bone marrow. This information can help doctors recommend appropriate treatment and predict the patient’s likelihood of recovery.
TREATMENT
Treatment for lymphoma is tailored to each individual patient, depending on the type of lymphoma present, how fast it grows, and how far it has spread. In general, lymphomas that derive from T cells are more difficult to treat than B cell lymphomas, and patients over age 60 are less likely to be cured than younger patients. Lymphoma can easily spread throughout the body, so patients whose disease appears to be confined to one or a few lymph nodes may have collections of cancerous cells elsewhere in the body that are not big enough to be detected by the tests used in staging the disease. For this reason, the treatment of choice for lymphoma is usually chemotherapy—drugs given by mouth or through the veins to kill rapidly dividing cancer cells throughout the body. Radiation therapy, in which high-energy rays are directed at a specific part of the body, is sometimes given after a course of chemotherapy to help prevent a relapse.
Chemotherapy medicines and radiation are toxic to both lymphoma and normal cells, and they can cause a variety of side effects, including nausea and vomiting, hair loss, mouth sores, and skin irritation. More serious side effects can include infections, bleeding, and organ damage. Physicians have made great progress in controlling these complications, and most patients recover from all side effects after their treatment for lymphoma.
In patients whose lymphoma returns after treatment, doctors may use higher doses of chemotherapy or radiation in a second attempt to kill the cancerous cells. These intensive treatments also destroy the blood-forming cells in the patient’s bone marrow. After the high-dose chemotherapy or radiation treatment, stem cells, which are responsible for long-term formation of blood, must be infused into the patient in a procedure known as stem cell transplantation. The stem cells may be collected from the bone marrow or circulating blood of the patient before the chemotherapy or radiation treatment, or the cells may come from an immunologically matched donor, usually a parent or sibling.
Several recent innovations have improved treatment for lymphoma. These include antibody therapy, in which highly specific molecules known as monoclonal antibodies are used to destroy lymphoma cells with minimal effect on normal cells, and vaccine therapy, which helps stimulate the patient’s immune system to fight the lymphoma. Some of these treatments are still experimental and are very expensive. In recent years these and other new treatments, as well as better management of the side effects of chemotherapy, have improved the five-year survival rate for lymphoma from 31 percent in 1960 to 51 percent today.
Treatment for lymphoma is tailored to each individual patient, depending on the type of lymphoma present, how fast it grows, and how far it has spread. In general, lymphomas that derive from T cells are more difficult to treat than B cell lymphomas, and patients over age 60 are less likely to be cured than younger patients. Lymphoma can easily spread throughout the body, so patients whose disease appears to be confined to one or a few lymph nodes may have collections of cancerous cells elsewhere in the body that are not big enough to be detected by the tests used in staging the disease. For this reason, the treatment of choice for lymphoma is usually chemotherapy—drugs given by mouth or through the veins to kill rapidly dividing cancer cells throughout the body. Radiation therapy, in which high-energy rays are directed at a specific part of the body, is sometimes given after a course of chemotherapy to help prevent a relapse.
Chemotherapy medicines and radiation are toxic to both lymphoma and normal cells, and they can cause a variety of side effects, including nausea and vomiting, hair loss, mouth sores, and skin irritation. More serious side effects can include infections, bleeding, and organ damage. Physicians have made great progress in controlling these complications, and most patients recover from all side effects after their treatment for lymphoma.
In patients whose lymphoma returns after treatment, doctors may use higher doses of chemotherapy or radiation in a second attempt to kill the cancerous cells. These intensive treatments also destroy the blood-forming cells in the patient’s bone marrow. After the high-dose chemotherapy or radiation treatment, stem cells, which are responsible for long-term formation of blood, must be infused into the patient in a procedure known as stem cell transplantation. The stem cells may be collected from the bone marrow or circulating blood of the patient before the chemotherapy or radiation treatment, or the cells may come from an immunologically matched donor, usually a parent or sibling.
Several recent innovations have improved treatment for lymphoma. These include antibody therapy, in which highly specific molecules known as monoclonal antibodies are used to destroy lymphoma cells with minimal effect on normal cells, and vaccine therapy, which helps stimulate the patient’s immune system to fight the lymphoma. Some of these treatments are still experimental and are very expensive. In recent years these and other new treatments, as well as better management of the side effects of chemotherapy, have improved the five-year survival rate for lymphoma from 31 percent in 1960 to 51 percent today.
