The stage of a cancer is how much and how far the cancer has spread in your body. Your doctor uses exams and tests to find your cancer stage. The stage is one of the most important things to know when deciding how to treat cancer.

Different systems are used to stage multiple myeloma. The most common system is the Revised International Staging System (R-ISS).

R-ISS is based on these four lab test results for the person with multiple myeloma:

1. How much beta-2 microglobulin (B2M) is in the blood?
2. How much albumin is in the blood?
3. How much lactate dehydrogenase (LDH) is in the blood?
4. What are the DNA changes in the myeloma cells? (This is called cytogenetics.)
   • DNA is contained in chromosomes. DNA is made of genetic information. A cytogenetic test called FISH (fluorescence in situ hybridization) looks for abnormal genetic changes in the myeloma cells.

The R-ISS divides multiple myeloma into three stages:

Stage I includes myelomas with all of the following:

• B2M is less than 3.5 mg/L
• Albumin is 3.5 g/dL or higher
• LDH level is normal
• The myeloma cells don't have any high-risk chromosome changes

Stage II includes all myelomas that don't fall into stage I or stage III.

Stage III includes myelomas with a B2M of 5.5 mg/L or greater, plus at least one of the following:

• The myeloma cells have high-risk chromosome changes
• LDH level is high

Along with the stage of a myeloma, other factors can also affect a person's outlook (prognosis). For instance, people who are younger tend to do better than those who are older. People who have better kidney function also tend to do better than those whose kidneys are damaged by the myeloma.

Once your cancer is staged, your doctor will talk with you about what the stage means for your treatment. Ask any questions you have. Make sure to talk about your concerns.