Multiple myeloma typically affects areas where the bone marrow is still active in adults, such as the skull, spine, ribs, pelvis, and shoulder region. Other areas, such as the bones of the hands, feet, forearms, and lower legs, are usually less affected.
1. What is Multiple Myeloma?
Cancer begins when cells grow out of control. Cells in almost any part of the body can become cancerous and can spread to other organs. Multiple myeloma is a cancer of plasma cells. Normal plasma cells are found in the bone marrow and are an important part of the immune system.
The immune system is made up of several types of cells that work together to fight infections and other diseases. Lymphocytes (white blood cells) are one of the main types of cells in the immune system, including T cells and B cells. Lymphocytes are present in many parts of the body, such as lymph nodes, bone marrow, intestines, and blood.
When B cells respond to an infection, they mature and change into plasma cells. Plasma cells produce antibodies (also known as immunoglobulins) that help the body attack and destroy pathogens. Plasma cells are primarily found in the bone marrow (which is the soft tissue inside bones). In addition to plasma cells, normal bone marrow is also home to other blood cells such as red blood cells, white blood cells, and platelets.
Multiple myeloma is a disease related to the immune system.
In general, when plasma cells become cancerous and grow uncontrollably, it is called multiple myeloma. Plasma cells produce an abnormal type of protein (antibody) known by various names, such as monoclonal immunoglobulin, monoclonal protein (M-protein), M-spike, or paraprotein.
However, there are other disorders that also have abnormal plasma cells but do not meet the criteria to be called active multiple myeloma. Other plasma cell disorders include:
Monoclonal gammopathy of uncertain significance (MGUS)
Smoldering multiple myeloma (SMM)
Solitary plasmacytoma
Light chain amyloidosis
2. Characteristics of multiple myeloma
2.1 Low blood counts
In multiple myeloma, the excessive growth of plasma cells in the bone marrow can overshadow normal blood cells, leading to low blood counts.
This can cause anemia (lack of red blood cells), making the body weak and fatigued.
Multiple myeloma can also result in low platelets in the blood (thrombocytopenia), which may increase the risk of bleeding and bruising.
Another condition that may occur is leukopenia (lack of normal white blood cells), which can lead to infection-related problems.
2.2 Bone and Calcium Issues
Bones are continuously remodeled to keep them strong. Two types of bone cells work together to maintain bone strength:
Osteoclasts break down old bone
Osteoblasts create new bone
Cells in multiple myeloma also interfere with these cells. Myeloma cells produce a substance that accelerates the activity of osteoclasts, leading to increased bone destruction. As a result, old bones are broken down without new bone to replace them, making the bones weak and prone to fractures. Bone fractures are a significant issue for individuals with multiple myeloma. This increased bone breakdown can also raise the levels of calcium in the blood.
Bone marrow biopsy images in multiple myeloma
2.3 Infections
Abnormal plasma cells cannot protect the body from infections. As mentioned, normal plasma cells produce antibodies that attack microbes. In multiple myeloma, the myeloma cells overshadow normal plasma cells, leading to a lack of antibodies against infections.
2.4 Kidney Issues
Myeloma cells produce an antibody that can harm the kidneys, resulting in kidney damage and even kidney failure.
3. Causes, risk factors, and prevention methods
Learn about the risk factors for multiple myeloma and what can help reduce the risk.
3.1 Risk Factors
A risk factor is anything that affects the likelihood of developing a disease such as cancer. Different cancers have different risks. For example, exposure of the skin to strong sunlight is a risk factor for skin cancer.
Smoking is a risk factor for lung cancer and many other cancers. But risk factors do not tell us everything. People without risk factors can still develop the disease. Conversely, having a risk factor, or even several, does not mean that one will definitely develop the disease.
Below are a few risk factors that may influence the likelihood of developing multiple myeloma.
Age: the risk of multiple myeloma increases with age. Less than 1% of cases are diagnosed in people under 35 years old. Most people diagnosed with this cancer are at least 65 years old.
Gender: men are more likely to develop multiple myeloma than women.
Family history: individuals with siblings or parents who have had myeloma are more likely to develop the disease than those without this family history. However, most patients do not have affected relatives, so family history accounts for only a small number of cases.
Obesity: being overweight or obese increases the risk of developing multiple myeloma.
Having other plasma cell disorders: individuals with monoclonal gammopathy of undetermined significance (MGUS) or solitary plasmacytoma have a higher risk of developing multiple myeloma compared to those without these conditions.
3.2 What are the causes of multiple myeloma?
Scientists do not yet know the exact causes of most cases of multiple myeloma. However, they have made progress in understanding how certain changes in DNA can cause plasma cells to become cancerous.
Some genes (parts of DNA) are responsible for controlling when their cells grow and divide. These growth-promoting genes are called oncogenes.
Other genes slow down cell growth or cause cells to die at the right time and are called tumor suppressor genes.
Cancer can be caused by mistakes, or defects, in DNA known as mutations in oncogenes or tumor suppressor genes.
Recent studies have found that abnormalities in certain oncogenes (such as MYC) develop early in plasma cell tumors. Changes in other oncogenes (such as the RAS gene) are often found in bone marrow plasma cells after treatment, and changes in tumor suppressor genes (such as the p53 gene) are associated with spreading to other organs.
Cells in multiple myeloma also show abnormalities in their chromosomes. In human cells, DNA is combined to form chromosomes. Although normal human cells contain 46 chromosomes, some cancer cells may have additional chromosomes (known as chromosomal amplification) or lack entirely or partially a chromosome (known as chromosomal deletion). A common finding in multiple myeloma cells is the loss of parts of chromosome 17. This deletion makes multiple myeloma more aggressive and resistant to treatment.
About half of the people with multiple myeloma have a part of one chromosome that has translocated to a part of another chromosome in the tumor cell, which is called chromosomal translocation. When translocation occurs near the region of an oncogene, it can cause mutations in that oncogene.
Researchers have found that patients with plasma cell tumors have significant abnormalities in other bone marrow cells, and these abnormalities may also lead to excessive plasma cell growth.
Some cells in the bone marrow (called dendritic cells) release a type of hormone called interleukin-6 (IL-6), which stimulates normal plasma cells to grow. The overproduction of IL-6 by these cells appears to be an important factor in the development of plasma cell tumors.
3.3 Prevention
For some types of cancer, the risk factors are known in most cases. For example, smoking causes most lung cancers, thus there is an opportunity for prevention.
In multiple myeloma, a few cases are associated with avoidable risk factors, while there is virtually no way to prevent others from developing.
Master, Resident Doctor Manh has 5 years of experience studying and working in the field of Cardiology. He graduated from Hanoi Medical University and continued his education in the cardiology residency program at Hanoi Medical University and Bach Mai Hospital.
He received his Master's degree and residency certification from Hanoi Medical University in 2020. He has participated in specialized training courses in cardiology, particularly in the diagnosis, intervention, and treatment of vascular diseases.
