Lymphoma is the most common hematologic (blood) cancer in the United States. When people think of cancer, they often think of a solid tumor that grows and sometimes spreads to other places in the body. Blood cancer, on the other hand, affects the blood, bone marrow and lymph nodes and may or may not create an actual tumor.
Lymphomas affect the lymphatic system and lymphocytes (a type of white blood cell) and can be classified into two main categories based on how the cancer cells look under a microscope or on the results of lab tests. Distinguishing between the types is important for determining a treatment strategy because the cancer cells act, spread and respond differently to treatment.
Non-Hodgkin lymphoma (NHL) is the most common cancer of the lymphatic system (see Non-hodgkin lymphoma). It is not a single disease but instead represents a group of closely related cancers. The World Health Organization estimates more than 60 subtypes of NHL exist. Although these subtypes share some common features, they differ in microscopic appearance, molecular features, how they grow, how they affect the body and how they are treated.
Hodgkin lymphoma is a cancer that starts in the lymphoid tissue, which is made up mostly of lymphocytes (see Hodgkin lymphoma). Although it can start in any part of the body that contains lymphoid tissue, Hodgkin lymphoma typically starts in the lymph nodes.
How Lymphoma Develops
Learning the basics of the lymphatic system (see Figure 1) will help you better understand lymphoma. The lymphatic system is made up of tissues and vessels that carry fluid, called lymph, throughout the body. Lymph contains lymphocytes, which attack infectious agents. Lymphocytes are concentrated in lymph nodes located along the course of lymphatic vessels.
Lymphoma develops when normal lymphocytes change into abnormal, cancerous cells that reproduce uncontrollably. The two main types of lymphocytes that can develop into lymphomas are B lymphocytes (B cells) and T lymphocytes (T cells). B cells make antibodies, which are proteins that attach to infectious organisms, such as bacteria and viruses, marking them for destruction. T cells attack infectious organisms directly and play a part in controlling the immune system. As lymphoma cells multiply, they collect in the lymph nodes, bone marrow, spleen, tonsils or other organs, where they can form tumors. These cells eventually begin to outnumber normal cells, causing an enlargement at one of these sites.
The treatment options available for each patient depend on the stage of the disease, including the extent of the lymphoma, the disease subtype, presence of symptoms and other general factors, such as the patient’s age, gender and overall health. Treatment options may include the following:
Watchful waiting is common for people who do not currently have symptoms and includes regular doctor visits along with frequent communication to discuss any new symptoms.
Chemotherapy may be used alone or in combination with radiation therapy, depending on the type and stage of the lymphoma. It is also often given in high doses before stem cell transplantation.
Immunotherapy is a type of treatment that uses the body’s own immune system to find and destroy cancer cells. Your body's immune system isn't always able to handle something as intense as cancer on its own, so doctors build on the healing capabilities of your immune system with immunotherapy.
Radiation therapy may be used to treat some early-stage lymphomas or in combination with chemotherapy for more advanced disease. It can also be used before stem cell transplantation.
Targeted therapy is treatment with drugs or other substances that stop cancer growth by interfering with the specific molecules involved in the development of tumor cells.
Stem cell transplantation may be appropriate for some people with lymphoma and is usually given after high-dose chemotherapy or radiation therapy.