Staging

Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancer.

The Durie-Salmon system has been traditionally used for the staging of myeloma. This staging system is good for assessing the extent of the disease or size of the tumor. According to this system there are three stages; each stage is further subclassified into A or B depending on whether kidney function has been affected (with the subclassification B meaning there is significant kidney damage).

Some doctors have proposed a new classification system called the International Staging System (ISS), which 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 serum albumin (a blood protein made by the liver that is necessary for maintaining proper blood volume) measurements and serum ß2-microglobulin (ß2-M) (a small protein that plays a role in immunologic defense) levels. Recent efforts involve classifying myeloma based upon patterns of gene expression in myeloma cells. It is also becoming more common to classify people with myeloma as symptomatic (having symptoms) versus asymptomatic (without symptoms).

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:

• Number of red blood cells within or slightly below normal range
  
  
• Normal amount of calcium in the blood
  
  
• Very low levels of M protein in the blood or urine
  
  
• No bone damage on x-rays
  
  
• ß2-M less than 3.5 grams per deciliter (gm/dL) and albumin greater than or equal to 3.5 gm/dL

Stage II

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:

• Anemia with a hemoglobin less than 8.5 gm/dL
  
  
• Hypercalcemia
  
  
• Advanced bone damage (more than three bone lesions)
  
  
• High levels of M protein in the blood or urine, which is defined as:
  
  IgG value greater than 7gm/dL
  IgA value greater than 5gm/dL
  Urine light chain M component on electrophoresis greater than 12gm/24h
  
  
• ß2-M greater than 5.5 gm/dL

Recurrent

Recurrent myeloma is myeloma that comes back after treatment.

Other classifications

Some people have no symptoms of myeloma, but they may have abnormal plasma cells producing an abnormal protein (M protein). Doctors generally monitor these people closely and do not actively treat them unless this condition turns into symptomatic myeloma.

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 20% to 25% chance of developing myeloma or lymphoma in the future. For this reason, doctors closely monitor the health of people with MGUS.

Smoldering multiple myeloma (SMM) or asymptomatic myeloma

People who are diagnosed with SMM have slightly higher levels of M protein and more plasma cells in the bone marrow than people with MGUS. There is still no evidence of symptoms or signs of myeloma, such as bone disease or anemia. Most people with SMM eventually develop myeloma.

Prognosis

The International Staging System (ISS) of myeloma gives information about prognosis and predicts the 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:

• High levels of ß2-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.
  
  
• Lower amounts of serum albumin may indicate a poorer prognosis.
  
  
• Lactase dehydrogenase (LDH) is an enzyme; higher blood levels of LDH indicate a poorer prognosis.
  
  
• Abnormalities of chromosomes in the cancer cells may show how aggressive a cancer is.
  
  
• 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.