Staging of DLBCL
After biopsy, staging determines exactly how much lymphoma is in the body and where it is located. Staging is typically done with a whole-body computed tomography (CT) scan or positron emission tomography (PET)/CT scan. A CT scan combines X-rays taken from many different angles into a single picture that gives a detailed image of organs inside the body. Patients with lymphoma often have CT scans of the neck, chest, abdomen, and pelvis to find out how many lymph nodes are involved, how large they are, and whether internal organs are affected by the disease. A PET scan involves injecting radioactive fluorodeoxyglucose (a type of sugar) into the body, and a positron camera is then used to detect the radioactivity and produce cross-sectional images of the body. PET scans can evaluate lymphoma activity in all parts of the body, and they can help distinguish active tumors from scar tissue. While CT scans show the size of a lymph node, PET scans show if the lymph node is active (has disease present). PET and CT scans are now often combined into a single test called a PET/CT scan.
Staging may also include a bone marrow biopsy to look for lymphoma cells in the bone marrow, and sometimes a lumbar puncture (spinal tap) to determine if there are lymphoma cells in the spinal fluid. The physician will use the results of these tests to assess the stage of the lymphoma. Staging is needed so the physician and patient can discuss and choose an appropriate course of treatment.
Until recently, the Ann Arbor staging system was the only one used to stage DLBCL. In 2014, a modified version of this system called the Lugano Classification was proposed, which is shown below. Both staging systems are currently in use. There are two classifications of disease – limited (affecting only one area of the body) and advanced (affecting several organs) – and four stages designated by the Roman numerals I through IV. The stages are described below.
In general, Stage I and Stage II cancers are considered limited, while Stage III and Stage IV cancers are considered advanced disease. However, Stage II disease that is bulky (has a tumor measuring more than 7.5 cm wide) is also considered advanced.
Unlike solid tumor cancers such as lung or breast cancer, in which the stage of the disease has significant implications for prognosis, stage is only one of many factors used to determine prognosis in the treatment of DLBCL. Doctors consider the stage of disease, test results, and several other factors (like those described in the IPI) when deciding the best time to begin treatment and what treatments are likely to be most effective for each patient.
Because lymphomas involve blood cells that circulate throughout the body, a large proportion of patients with DLBCL are diagnosed with advanced disease (Stage III or IV). It is important to remember that advanced disease is common in DLBCL and can be successfully treated.
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