For myeloma, it is important to begin with whether the patient is experiencing symptoms. It is common to classify patients with newly diagnosed myeloma as being either symptomatic from the disease (having symptoms and signs) or asymptomatic (without any symptoms). Patients without symptoms are generally watched closely without treatment, which is called active surveillance (see the Treatment Options section). Patients with symptoms need 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.
1. 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 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.
- 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.
Stage I
Many patients with stage I myeloma show no symptoms because there are fewer cancer cells in the body. If the cancer has affected kidney function, the prognosis may be worse regardless of the stage. Factors characteristic of stage I include:
- 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)
- Hemoglobin level is only slightly below normal (still above 10 g/dL)
- Only a relatively small amount of monoclonal immunoglobulin is in blood or urine
More cancer cells are present in the body in stage II. Again, if kidney function is affected, then the prognosis worsens regardless of the stage. Criteria for stage II are defined as those that fit neither stage I nor stage III.
Stage III
Many cancer cells are present in the body at stage III. Factors characteristic of this stage are:
- 3 or more areas of bone destroyed by the cancer
- High blood calcium level (above 12 mg/dL)
- Large amount of monoclonal immunoglobulin in blood or urine
- Low hemoglobin level (below 8.5 g/dL)
Another classification system called the International Staging System (ISS) is now used more commonly. It defines the factors that influence patient survival. The ISS is based on data collected from patients with multiple myeloma from around the world. The system has three stages based on the measurement of serum albumin and the levels of serum β2 microglobulin. Recent efforts involve further classifying myeloma based upon patterns of gene expression in myeloma cells; this is an ongoing area of research.
Stage I
Serum beta-2 microglobulin is less than 3.5 (mg/L) and the albumin level is above 3.5 (g/L)
Stage II
Neither stage I or III, meaning that either:
- The albumin is below 3.5 while the beta-2 microglobulin is less than 3.5, or
- The beta-2 microglobulin level is between 3.5 and 5.5 (with any albumin level).
Serum beta-2 microglobulin is greater than 5.5.
Recurrent or relapsed myeloma. Myeloma that returns after a period of being in control after treatment is called recurrent myeloma or relapsed myeloma. If there is a recurrence, the cancer may need to be staged again (called re-staging) using the system above.
Other Classifications
Age: Age is also important. In the studies of the international staging system, older people with myeloma do not live as long.
Chromosome Studies: The bone marrow may be sent for tests to look at the chromosomes in the malignant cells. Certain chromosome changes can indicate a poorer outlook. For example, changes in chromosome 13 will lower a person’s chances for survival. Another genetic abnormality that predicts a poor outcome is an exchange of material from chromosomes 4 and 14. This is called a translocation.
Kidney Function: 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.
Labeling Index: 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.
Monoclonal Gammopathy of Unknown Significance (MGUS): This condition occurs when people have a low level of M protein (meaning there are small quantities of abnormal plasma cells), but they do not have any other evidence of myeloma, such as bone damage, excessive plasma cells, or low numbers of red blood cells. People with MGUS have a 1% chance per year of developing myeloma or lymphoma. For this reason, doctors monitor the health of people with MGUS on a regular basis.
Prognosis: The International Staging System (ISS) of myeloma gives information about prognosis and predicts the person’s chance of recovery. Researchers are also looking at other ways to predict prognosis for patients with multiple myeloma. Some of these ways of evaluating prognosis include:
- A plasma cell labeling index can be done in a specialized laboratory using bone marrow samples to find out how fast the cancer cells are growing.
- Abnormalities of chromosomes in the cancer cells may show how aggressive the cancer is.
- High levels of β2-M may indicate a large number of myeloma cells are present and kidney damage has occurred. The level of this protein increases as myeloma becomes more advanced.
- Lactase dehydrogenase (LDH) is an enzyme; higher blood levels of LDH indicate a poorer prognosis.
- Lower amounts of serum albumin may indicate a poorer prognosis.