Lymphoma is a type of cancer that originates in infection-fighting cells of the immune system called lymphocytes. These specialized white blood cells are found throughout the body, including in lymph nodes, the spleen, and bone marrow. When lymphocytes grow uncontrollably or fail to die as they should, they can form tumors, leading to lymphoma. There are two main categories of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma, which differ in their cellular characteristics and behavior.
Why Lymphoma Staging Matters
Staging lymphoma after diagnosis helps healthcare professionals understand how far the cancer has spread and its locations. The extent of the disease influences treatment choices and predicts a patient’s prognosis. Understanding the stage allows doctors to tailor therapies, ensuring the most effective approach. For example, localized disease might require less intensive treatment than widespread cancer. Staging also offers insights into the lymphoma’s aggressiveness and its likelihood of responding to interventions.
The Ann Arbor Staging Framework
The Ann Arbor Staging System, also known as the Lugano Classification, is the primary system used to classify lymphoma. It categorizes lymphoma based on its anatomical location and spread relative to the diaphragm, using Roman numerals I through IV for increasing disease spread.
Beyond numerical stages, additional letters provide detail. “B” indicates systemic symptoms like unexplained fever, night sweats, or weight loss; “A” means these symptoms are absent. “E” signifies extranodal involvement (cancer spread outside lymph nodes to a single organ), while “S” indicates spleen involvement.
Detailed Lymphoma Stages
The Ann Arbor classification defines four stages, each representing a different extent of disease.
Stage I
Stage I indicates the most localized form of lymphoma. The cancer is found in only one lymph node region or a single extralymphatic organ or site. This means the lymphoma is confined to a single area, such as a cluster of lymph nodes in the neck or a solitary tumor in an organ like the thyroid gland.
Stage II
Stage II describes lymphoma spread to more than one lymph node region, with all affected areas on the same side of the diaphragm. It can also include localized involvement of a single extralymphatic organ or site along with one or more lymph node regions, provided all affected areas remain on the same side of the diaphragm. For example, if lymph nodes in the armpit and neck are involved and both are above the diaphragm, it is Stage II.
Stage III
Stage III lymphoma has spread to lymph node regions on both sides of the diaphragm. This includes affected lymph nodes both above and below this muscle. Stage III can also include lymph nodes above the diaphragm with lymphoma present in the spleen.
Stage IV
Stage IV represents the most widespread form of lymphoma, indicating diffuse involvement. The cancer has spread extensively to one or more extralymphatic organs, such as the lungs, liver, or bone marrow, with or without associated lymph node involvement. This can also mean diffuse involvement of these organs, where the disease is not confined to isolated areas.
Beyond Numerical Staging
While Ann Arbor stages provide a framework, other factors influence a patient’s outlook and treatment. The specific lymphoma subtype plays a role, as types like diffuse large B-cell lymphoma or follicular lymphoma behave and respond to treatment uniquely. This means lymphomas at the same numerical stage can have different prognoses.
Clinicians use prognostic indices like the International Prognostic Index (IPI) for a comprehensive understanding. This tool combines risk factors including age, performance status, lactate dehydrogenase (LDH) levels, and number of extranodal sites. These indices offer a personalized risk assessment beyond the stage. Bulky disease, a tumor mass greater than 10 centimeters, is another consideration that can affect treatment intensity. How lymphoma responds to initial therapy also guides subsequent treatment decisions.