How Ann Arbor Staging Works for Lymphoma

The first standard action once cancer is diagnosed is "staging": an assessment of how far it has spread throughout the body. Lymphoma is traditionally staged according to what is known as the Ann Arbor system, which stages cancer between Stage I (localized disease) and Stage IV (metastasis, or spread, throughout the body). This is similar to the TNM system used in other solid cancers.

For lymphoma, the Ann Arbor stages mean:

Stage I	Localized Disease: one lymph node or one group of lymph nodes.
Stage II	Two or more groups of lymph nodes, all of which are either above or below the diaphragm.
Stage III	Disease has spread to lymph nodes throughout the body, both above and below the diaphragm.
Stage IV	Disease has spread beyond the lymphatic system, including to the bone marrow.

The majority of people with lymphoma, especially indolent lymphomas, already have "advanced" disease (Stage III or Stage IV) when it is first diagnosed. This is because lymphoma almost never has significant symptoms in its early stages (other than slowly growing lymph nodes), and often spreads relatively early on in the disease, as the malignant white blood cells naturally migrate around the body.

In most solid tumours, advanced disease is an extremely serious prognostic factor. This is still true in lymphoma, but much less so. Lymphoma is highly response to chemotherapy, and even Stage IV disease can still be treated very effectively. Studies published several years ago indicated that the 5-year survival rate for follicular lymphoma might be as high as 95%. Healthy and malignant immune system cells naturally move around the body. For this reason, disease progression in lymphoma, while worrying, is still less worrying than metastasis of cells which shouldn't circulate around the body, such as in lung cancer or breast cancer.

At the same time, the earlier the disease is caught, the more effective treatment may be. In the small minority of patients who catch their disease in Stage I or Stage II, it may actually be curable with immediate, aggressive treatment. Traditionally, follicular lymphoma is classified incurable once it reaches Stage II, or in some Stage II patients where at least one malignant growth is more than 7-10 cm long. This is known as "bulky" disease.