When most people think of cancer, they think of solid cancer that involves a tumor that grows and sometimes spreads to other places in the body. Lymphomas, however, fall into a different category of cancers called hematological (blood) cancers. Blood cancers primarily affect the blood, bone marrow and lymph nodes and may or may not create an actual tumor.
Lymphoma is the most common blood cancer in the United States. This disease specifically affects the lymphatic system and lymphocytes, which are part of the immune system, and it can occur in adults and children of any age. Lymphoma can be classified into two main categories: Hodgkin lymphoma and non-Hodgkin lymphoma.
Development of lymphoma
To fully understand lymphoma, it’s important to first gain a general knowledge of the lymphatic system. This network of tissues and vessels carries fluid, called lymph, throughout the body (see Figure 1). Lymph contains lymphocytes that attack infectious agents. Lymphocytes are concentrated in lymph nodes located along the course of lymphatic vessels.
The two main types of lymphocytes that can develop into lymphomas are B-lymphocytes (B-cells) and T-lymphocytes (T-cells). B-cells produce protein antibodies 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. Both B-cells and T-cells can transform into lymphoma cells. In the United States, B-cell lymphomas are much more common.
Lymphoma develops when normal lymphocytes (a type of white blood cell) transform into abnormal, cancerous cells that reproduce uncontrollably. As they 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.
Risk factors for lymphoma
While the exact cause of lymphoma is unknown, mutations in DNA (the hereditary genetic material found in cells) lead to the development of the disease. What triggers these mutations is also largely unknown, but research suggests that certain risk factors may play a role, including:
Exposure to high levels of radiation
Long-term exposure to certain chemicals
Exposure to certain hair dyes, particularly those made before 1980
Inherited and acquired immune system disorders
Certain infections, such as the Epstein-Barr virus and Helicobacter pylori infection
Symptoms of lymphoma
Symptoms of lymphoma vary among patients and depend on the type of lymphoma and the area of the body where the lymphocytes collect. The most common symptom of lymphoma is swelling in one or more lymph nodes in the neck, armpits, chest, abdomen or groin.
While swollen nodes are generally tender and often hurt to some degree in people with infections, they tend to be firm and painless in people with lymphoma. Other common symptoms of lymphoma include fever, chills, night sweats, chest pain, lower back pain, unexplained weight loss, rashes, itchy skin, skin lesions and fatigue.
Treatment of lymphoma
Advancements in lymphoma treatment have been steadily improving patient outcomes over the last few decades, and recent clinical trials for new types of treatments and drug combinations have shown high survival rates. 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. Some treatment options include the following:
Watchful waiting is common for people with low-grade (slow-growing) lymphoma who do not currently have symptoms.
Chemotherapy may be used alone or in combination with radiation therapy depending on the type and stage of the lymphoma. It is often given in high doses before stem cell transplantation.
Radiation therapy may be used to treat certain early-stage lymphomas or in combination with chemotherapy for more advanced disease. It also can be used before stem cell transplantation.
Targeted therapy involves the use of drugs or other substances that block the growth and progression of cancer by interfering with the specific molecules involved in tumor cell development. Researchers are continuing to discover new molecules on the surface of lymphoma cells that are responding to targeted therapy treatments.
Immunotherapy uses the body’s own immune system to find and destroy cancer cells. Monoclonal antibodies, a type of immunotherapy, can be used alone or packaged to deliver potent cancer treatments.
Stem cell transplantation may be appropriate for some people with lymphoma and is often given after high-dose chemotherapy or radiation therapy.
See here for a more detailed breakdown of common treatment options by specific type of lymphoma.