Natural killer (NK)/T-cell lymphoma is a type of non-Hodgkin lymphoma. NK/T-cell lymphoma is also called extranodal NK/T-cell lymphoma or extranodal NK/T-cell lymphoma, nasal type.

Lymphoma cells are cancer cells that originate from lymphocytes, a type of white blood cell. Lymphoma occurs in the lymphatic system, which is part of the immune system. It includes the lymph nodes, spleen, tonsils, and other lymphoid organs. All together, this system helps remove bacteria, waste, and excess fluid from tissue.

What Is NK/T-Cell Lymphoma?

NK/T-cell lymphoma is a rare and very aggressive type of non-Hodgkin lymphoma. It develops from two types of lymphocytes: NK cells and cytotoxic T cells (T cells). NK/T-cell lymphoma is very rare in North America and Europe. It’s seen more commonly in people from Asia, South America, and Central America.

NK/T-cell lymphoma is an extranodal lymphoma, meaning that it occurs outside of lymph nodes or other lymphatic system organs. It usually occurs inside the nose (the nasal cavity), the sinuses, and the upper airway. It can also occur in the skin, digestive tract, or other organs throughout the body.

When advanced NK/T-cell lymphoma involves the blood and bone marrow, it can become NK/T-cell leukemia. NK/T-cell lymphoma is one of several types of lymphoma that is associated with infection by the Epstein-Barr virus, the virus that causes infectious mononucleosis.

Symptoms of NK/T-Cell Lymphoma

NK/T-cell lymphoma forms fast-growing tumors that can rapidly invade and destroy surrounding tissue.

Symptoms of NK/T-cell lymphoma in the nose include a blocked nasal airway, nosebleeds, facial swelling, and watery eyes. Skin symptoms can include a rash or lumps in the skin. Skin lesions can break down and bleed.

Other symptoms include:

• Enlarged lymph nodes (lymphadenopathy), though this is uncommon
• B symptoms (unexplained fever, drenching night sweats, and unexplained weight loss)
• More frequent infections
• Fatigue

Diagnosis of NK/T-Cell Lymphoma

Diagnosis of NK/T-cell lymphoma begins with a thorough medical history and physical exam. If your doctor suspects you may have this type of lymphoma, they might also order:

• Imaging tests — These may include positron emission tomography (PET), CT, or MRI scans, used to help find tumors throughout the body.
• Blood tests — These may include a complete blood count, lactate dehydrogenase level test, standard tests for liver and kidney function, and tests for diseases that affect the immune system, including HIV and viral hepatitis
• Biopsies to confirm and identify cancer cells — A doctor may collect a small tissue sample surgically or with a small needle to test for the presence of cancer cells.

Cancer cells can also be tested with immunophenotyping. This technique can identify surface antigens (proteins on the cell surface) or find specific genetic mutations associated with certain cancers. Several surface antigens are regularly seen in NK/T-cell lymphoma. The most common is CD56, a marker for NK cells and cytotoxic T cells. A large number of NK/T-cell lymphoma cells also contain EBV DNA, which shows infection with the Epstein-Barr virus.

NK/T-Cell Lymphoma Staging

Most types of lymphoma are staged using the Lugano classification system. Stages are based on whether the lymphoma is localized or widespread, especially if the lymphoma has spread from one side of the diaphragm (the large muscle under the ribs) to the other. Stages are defined further by the size of the tumor and whether lymphoma has spread beyond the lymphatic system. The Lugano stages include:

• Stage 1 and stage 2 — These are also referred to as early-stage or limited-stage. The lymphoma involves lymph nodes and/or one organ outside the lymphatic system on the same side of the diaphragm.
• Stage 3 and stage 4 — These are also referred to as late-stage or advanced-stage. The lymphoma has spread to both sides of the diaphragm and may include organs outside of the lymphatic system.

The International Prognostic Index is also used to assess the outlook of lymphomas. This system uses five factors to classify a person’s risk of a poor outcome:

• The person’s age
• The lymphoma’s stage
• Whether the lymphoma has spread outside of the lymphatic system
• How well a person can perform activities of daily living
• Lactate dehydrogenase levels in the blood

What Causes NK/T-Cell Lymphoma?

Broadly speaking, cancer is caused by genetic mutations that allow cells to grow and divide out of control. Lymphomas can be caused by inherited genes or acquired mutations. Acquired mutations occur due to exposure to things such as radiation, some chemicals, and certain infections. Infection with the Epstein-Barr virus is associated with several different types of lymphoma, including NK/T-cell lymphoma. Exactly how this virus contributes to the development of lymphoma is not understood.

Treatment of NK/T-Cell Lymphoma

The primary treatment for NK/T-cell lymphoma is chemotherapy, either with or without radiation (radiotherapy). Localized radiation is sometimes used along with chemotherapy to treat nasal type NK/T-cell lymphoma. Other treatment options include targeted therapies and clinical trials.

Chemotherapy regimens for NK/T-cell lymphoma are different from regiments used for other types of non-Hodgkin lymphoma. Commonly used anthracycline drugs like doxorubicin (Adriamycin) are not used, but the drug L-asparaginase has become a key component of NK/T-cell lymphoma treatment. The two main chemotherapy regimens used in treatment are:

• SMILE — Dexamethasone (a corticosteroid), methotrexate, ifosfamide, L-asparaginase, and etoposide (VP-16)
• AspaMetDex — L-asparaginase, methotrexate, and dexamethasone

NK/T-cell lymphoma that is refractory (does not respond to treatment) or relapsed (returns after treatment) may be treated with alternative chemotherapy regimens or an allogeneic (donor) stem cell transplant.

NK/T-Cell Lymphoma Outlook

NK/T-cell lymphoma is very aggressive and generally has a poor prognosis, or disease outlook. The five-year overall survival rates for new and recurrent disease, even using the most effective therapies, are around 50 percent. However, new treatment approaches are being developed and tested to improve disease outcomes.

Talk With Others Who Understand

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