The lymph system is a series of lymph nodes and vessels that move lymph fluid through the body. Lymph fluids contain infection-fighting white blood cells. Lymph nodes act as filters, capturing and destroying bacteria and viruses to prevent infection from spreading.

While the lymph system typically protects your body, lymph cells called lymphocytes can become cancerous. The names for cancers that occur in the lymph system are lymphomas. According to the Memorial Sloan Kettering Cancer Center (MSKCC), an estimated 75,000 Americans are diagnosed with lymphoma each year.

Doctors classify more than 60 cancer types as lymphomas. Lymphomas can affect any portion of the lymphatic system, including:

  • bone marrow
  • thymus
  • spleen
  • tonsils
  • lymph nodes

Doctors typically divide lymphomas into two categories, Hodgkin’s lymphoma and non-Hodgkin’s lymphoma.

The two major lymphoma types are Hodgkin’s lymphoma and non-Hodgkin’s lymphoma (NHL). A pathologist in the 1800s named Dr. Thomas Hodgkin identified the cells in what is now called Hodgkin’s lymphoma. Those with Hodgkin’s lymphoma have large cancerous cells called Reed-Sternberg cells. People with NHL don’t have these cells.

According to the Leukemia & Lymphoma Society (LLS), NHL is three times more common than Hodgkin’s lymphoma.

Many lymphoma types fall under each category. Doctors call NHL types by the cells they affect, and if the cells are fast- or slow-growing. NHL forms in either the B-cells or T-cells of the immune system. According to LLS, most NHL types affect B-cells. Types include:

  • B-cell lymphoma
  • Burkitt lymphoma
  • follicular lymphoma
  • mantle cell lymphoma
  • primary mediastinal B cell lymphoma
  • small lymphocytic lymphoma
  • Waldenstrom macroglobulinemia (also known as lymphoplasmacytic lymphoma)

Hodgkin’s lymphomas typically start in B-cells or immune system cells known as Reed-Sternberg cells. Hodgkin’s lymphoma types include:

  • lymphocyte-depleted Hodgkin’s disease
  • lymphocyte-rich Hodgkin’s disease
  • mixed cellularity Hodgkin’s lymphoma
  • nodular lymphocyte-predominant Hodgkin’s disease (a rare form)
  • nodular sclerosis Hodgkin’s lymphoma

Most diagnosed lymphoma cases have no known cause. However, some people are considered higher risk. This includes people with immune system disorders, such as:

  • human immunodeficiency virus (HIV)
  • those who take anti-rejection medications after organ transplant
  • those with a genetic immune system disorder

People who have had infections such as the human T-cell leukemia/lymphotropic virus (HTLV-1), Heliobacter pylori, hepatitis C, or the Epstein-Barr virus are associated with an increased risk. Those exposed to chemicals in pesticides, fertilizers, and herbicides are also at increased risk. Exposure to these infections or chemicals doesn’t mean a person will get lymphoma.

People who have undergone radiation treatments in the past also have a greater chance of having lymphoma.

According to LLS, most patients with lymphoma first notice swollen lymph nodes. These may feel like small, soft nodules under the skin. A person may feel the lymph nodes in the:

  • neck
  • upper chest
  • armpit
  • stomach
  • groin

Other lymphoma symptoms include:

  • bone pain
  • cough
  • fatigue
  • enlarged spleen
  • fever
  • night sweats
  • pain when drinking alcohol
  • rash
  • shortness of breath
  • skin itching
  • stomach pain
  • unexplained weight loss

Lymphoma may not always cause symptoms in its early stages. A doctor may discover enlarged lymph nodes during a physical examination.

A biopsy typically is taken if a doctor suspects lymphoma. This involves removing cells from an enlarged lymph node. A doctor known as a hematopathologist will examine the cells to determine if lymphoma cells are present and what cell type they are.

If the hematopathologist detects lymphoma cells, further testing can identify how far the cancer has spread. These tests can include a chest X-ray, blood testing, or testing nearby lymph nodes or tissues. Imaging scans, such as a computed tomography (CT) or magnetic resonance imaging (MRI) scans may also identify additional tumors or enlarged lymph nodes.

A number of medical specialists collaborate to treat lymphoma. These include hematologists, doctors who specialize in blood, bone marrow, and immune cell disorders. Oncologists treat cancerous tumors. Pathologists may work with these doctors to assist in treatment planning and identify if a particular treatment is working.

Lymphoma treatments depend upon the cancer’s stage. Doctors will “stage” a tumor to signify how far the cancerous cells may have spread. A stage 1 tumor is limited to a few lymph nodes, while a stage 4 tumor has spread to other organs, such as the lungs or bone marrow.

Doctors also “grade” NHL tumors by how fast they’re growing. These terms include:

  • low-grade or indolent
  • intermediate-grade or aggressive
  • high-grade or highly aggressive

Treatment for Hodgkin’s lymphoma includes radiation therapy to shrink and kill cancerous cells. Doctors also prescribe chemotherapy medications to destroy cancerous cells.

Chemotherapy and radiation are also used to treat NHL. Biological therapies that target cancerous B-cells also can be effective. An example of this drug type includes rituximab.

In some instances, a bone marrow or stem cell transplant is used to build up healthy immune system cells. Doctors may harvest these cells or tissues before beginning chemotherapy and radiation treatments. Relatives may be able to donate bone marrow too.

According to the Leukemia & Lymphoma Society, Hodgkin’s lymphoma is a highly curable cancer. Survival rates for both NHL and Hodgkin’s lymphoma depend upon how far the cancerous cells have spread and the cancer type. According to the American Cancer Society (ACS), the overall five-year survival rate for NHL patients is 69 percent and the 10-year survival rate is 58 percent. The survival rate for Hodgkin’s lymphoma depends upon its stage. The 5-year survival rate for stage 1 is 90 percent, while the 5-year survival rate for stage 4 is 65 percent.