How is multiple myeloma staged?
Staging is the process of finding out how much the cancer has advanced. It is important for treatment options and prognosis. Prognosis is a prediction of the course of disease – the outlook for survival. Knowing all you can about staging lets you take a more active role in making informed decisions about your treatment.
Multiple myeloma may be staged using the Durie-Salmon system. Although some doctors use this system, its value is becoming limited because of newer diagnostic methods. Recently, a new staging system called the International Staging System for Multiple Myeloma has been developed. It relies mainly on levels of albumin and beta-2-microglobulin in the blood. Other factors that may be important are kidney function, platelet count and the patient’s age.
The Durie-Salmon staging system
This system is based on 4 factors:
- The amount of abnormal monoclonal immunoglobulin in the blood or urine: Large amounts of monoclonal immunoglobulin indicate that many malignant plasma cells are present and are producing that abnormal protein.
- The amount of calcium in the blood: High blood calcium levels can be related to advanced bone damage. Because bone normally contains lots of calcium, bone destruction releases calcium into the blood.
- The severity of bone damage based on x-rays: Multiple areas of bone damage seen on x-rays indicate an advanced stage of multiple myeloma.
- The amount of hemoglobin in the blood: Hemoglobin carries oxygen in red blood cells. Low hemoglobin levels mean you are anemic and can indicate that the myeloma cells occupy much of the bone marrow and that not enough space is left for the normal marrow cells to make enough red blood cells.
This system uses these factors to divide myeloma into 3 stages. Stage I indicates the smallest amount of tumor, and stage III indicates the largest amount of tumor:
A relatively small number of myeloma cells are found. All of the following features must be present:
- Hemoglobin level is only slightly below normal (but still above 10 g/dL)
- Bone x-rays appear normal or show only 1 area of bone damage
- Calcium levels in the blood are normal (less than 12 mg/dL)
- Only a relatively small amount of monoclonal immunoglobulin is in blood or urine
A moderate number of myeloma cells are present. Features are between stage I and stage III.
A large number of myeloma cells are found. One or more of the following must be present:
- Low hemoglobin level (below 8.5 g/dL)
- High blood calcium level (above 12 mg/dL)
- 3 or more areas of bone destroyed by the cancer
- Large amount of monoclonal immunoglobulin in blood or urine
The International Staging System
This system divides myeloma into 3 stages based only on the serum beta-2 microglobulin and serum albumin levels.
Serum beta-2 microglobulin is less than 3.5 (mg/L) and the albumin level is above 3.5 (g/L)
Neither stage I or III, meaning that either:
The beta-2 microglobulin level is between 3.5 and 5.5 (with any albumin level),
The albumin is below 3.5 while the beta-2 microglobulin is less than 3.5
Serum beta-2 microglobulin is greater than 5.5.
Factors other than stage that affect survival
The blood creatinine (Cr) level shows how healthy the kidneys are. Kidneys eliminate this chemical from the body. When they are damaged by the monoclonal immunoglobulin, blood creatinine levels rise, predicting a worse outlook.
Age is also important. In the studies of the international staging system, older people with myeloma do not live as long.
The myeloma cell labeling index, sometimes called the plasma cell labeling index, indicates how fast the cancer cells are growing. This test is done in specialized labs, using myeloma cells from bone marrow samples. A high labeling index can predict a more rapid accumulation of cancer cells and a worse outlook.
The bone marrow may be sent for tests to look at the chromosomes in the malignant cells. Certain chromosome changes can mean a poorer outlook. For example, loss of a copy of chromosome 13 is linked to a poorer outcome. Another genetic abnormality that predicts a poor outcome is an exchange of material from chromosomes 4 and 14. This is called a translocation. Having extra copies of a certain area on chromosome 1 (an amplification of 1q21) is also linked to a poorer outcome.
Last Medical Review: 05/22/2014
Last Revised: 06/16/2014