After the diagnosis is made and before treatment can begin, one more very important process, called staging, has to be completed. Staging is a sequence of procedures that allows doctors and you to determine how widely the lymphoma has spread in your body and if organs other than lymph nodes are involved. The importance of staging is not only to gain knowledge, but also to guide treatment.
The biggest part of staging consists of imaging tests that typically include CT scan (computer-assisted tomography) and PET Scan (positron emission tomography) of all body compartments (i.e., neck, chest, abdomen and pelvis). In this modern day of age, these two techniques are commonly combined into one to save time and resources. The reason two different techniques are used to stage lymphoma is that they use different features of the lymphoma to accurately determine its location. A CT scan can detect lymph nodes involved by lymphoma based predominantly on their size (normal versus enlarged), while a PET scan detects lymphoma by sensing increased metabolism produced by the tumor even in normal sized lymph nodes. Consequently, a PET scan may be able to detect a lymphoma location where a CT scan may fail. Both CT scans and PET scans are capable of detecting lymphoma that has spread to organs other than lymph nodes.
The final procedure in accurately staging lymphoma is a bone marrow biopsy. Since bone marrow is present in every bone of the human body, a biopsy is generally performed on the biggest bone in the safest location; namely, the back of the pelvic bone. The result of a bone marrow biopsy from one site is reflective of all bone marrow in the rest of the body; if the bone marrow in the pelvic bone is involved by lymphoma it means that all bone marrow in the body is involved. Because lymphomas involve bone marrow in a diffuse fashion (not growing as a tumor, but mixing-in with other bone marrow cells), CT and PET scans are unable to detect bone marrow involvement. Hence, a bone marrow biopsy is the only way to determine this.
After all the above-mentioned procedures are completed, your doctor will inform you of what stage lymphoma you have. There are 4 stages of lymphoma.
- Stage I: Lymphoma involves one or several lymph nodes in one location; this location can be anywhere—armpit, neck, groin, etc.
- Stage II: Lymphoma involves lymph nodes in more than one location, but only on one side of the diaphragm (flat muscle that separates your body right across the middle into the upper and lower part, or by separating your chest cavity from your abdominal cavity).
- Stage III: Lymphoma involves lymph nodes on both sides of the diaphragm; the number of locations does not matter.
- Stage IV: Lymphoma involves other organs, rather than lymph nodes alone; examples include the bone marrow, lungs, liver, intestines, etc. Please note that the spleen is not considered “other organs,” and involvement of the spleen does not indicate stage IV disease.
Of note, for the purpose of therapy, stages I and II are combined into early stage disease; consequently, stages III and IV are combined into advanced stage disease.
In addition, designations “A” or “B” are also assigned to every stage. They indicate the absence (A) or presence (B) of one or more of the following symptoms: recurrent, unexplained fevers; severe/drenching night sweats and significant weight loss.
Based on the explanation above you should now be able to understand how the following examples are derived: Stage IA, IIB, IIIA, IVB, etc.