OVERVIEW
Multiple myeloma is a cancer that originates in the bone marrow, in which myeloma cells build up in the bone marrow. Bone marrow is a soft tissue in bones, where most blood cells are produced.
Plasma cells are the white blood cells involved in fighting the infection. Plasma cells generate antibodies, proteins that are involved in fighting the infection. Genetic alterations in the plasma cells turn them into myeloma cells. Myeloma cells divide rapidly, are produced in excess numbers, and don't die quickly. These myeloma cells eventually cause a clump that destroys the bone marrow.
In multiple myeloma, myeloma cells outnumber healthy cells. It causes bone pain and leads to fractures.
Myeloma cells produce antibodies called M-proteins, which do not fight any infection.
There is a significant development in the available therapies for multiple myeloma, which helped improve patients' overall survival.
CAUSES
There is no specific reason for the cause of multiple myeloma. Myeloma, like other cancers, occurs because of mutations in normal cells. These mutations generally do not pass through families and are non-hereditary.
TYPES OF MYELOMA
Active myeloma
Myeloma that causes symptoms and needs medical intervention is called active myeloma. The symptoms include bone pain, infections, fatigue, etc. The myeloma has at least 10% of abnormal plasma cells in the bone marrow.
Smoldering myeloma
Myeloma that has no symptoms and requires no medical intervention is called smoldering myeloma. People with smoldering myeloma have M-protein in their plasma and blood; however, not in high quantities.
SYMPTOMS
Bone damage and pain: During myeloma, the myeloma cells outnumber the normal cells, causing bone damage. They also release protein that damages the bone, causing fractures. The most common site of bone fractures is the spine.
Fatigue: Fatigue can be a symptom because of anemia. It occurs because myeloma cells outnumber the red blood cells in the bone marrow.
High infection rates: Because of fewer antibodies and normal white blood cells, frequent fevers and infections occur.
Easy bleeds: Platelets are responsible for blood clots; myeloma cells outnumber the platelets during myeloma. This causes bleeds or bruising.
Thirsty and frequent urination: The kidneys get damaged because of the excess M-protein. This might lead to either increase or decrease in urination.
Also read: SMA overview, diagnosis, and treatment
DIAGNOSIS
Blood tests - Blood tests help in the diagnosis of multiple myeloma
CBC help estimate blood cells count, including red blood cells and platelets. In multiple myeloma patients, few normal cells are present in the blood.
The serum protein electrophoresis (SPEP) test measures the M-protein present in the body.
The serum immunofixation electrophoresis (SIFE) test determines the type of M-proteins in the blood.
Blood chemistry tests determine the levels of chemicals in the blood.
Urine tests: Urine tests help determine the amount of proteins, which can help to measure the tumor burden.
Urine protein electrophoresis (UPEP) determines the quantity of M-proteins and light chains. High-light chains indicate a high risk of kidney damage.
The urine immunofixation electrophoresis (UIFE) test determines the type of M-proteins in the urine.
Tissue tests
Bone marrow biopsy: A bone marrow biopsy is critical for determining multiple myeloma, usually taken from the pelvic bone. A small solid and liquid bone are removed for testing in the bone biopsy.
Lab tests - The test removed in the bone marrow biopsy is tested.
Immunochemistry test is involved in determining the number and type of myeloma cells.
By checking the outer surface of the plasma cells, abnormal plasma cells can be identified.
Fluorescence in situ hybridization (FISH) testing helps determine the changes in the chromosomes of myeloma cells. The FISH test helps determine whether the myeloma is low or high risk.
Imaging tests: Imaging tests are the tests that take pictures of the inside of a patient's body.
Low-dose CT scan uses low X-rays to find the presence of lytic lesions. Lesions are involved in causing pain and weakening of bones.
PET/CT scan helps determine the spread of cancers. It is also helpful in determining bone damage.
Bone surveys include simple X-ray tests to check if there are any damages in the skeleton.
MRI scan uses radio waves and magnets to get images of the body. It helps in determining the areas where myeloma cells replace the bone marrow. It doesn't use radiation.
TREATMENT
The standard treatment of multiple myeloma includes a proteasome inhibitor, an immunotherapy drug, and corticosteroid. Chemotherapy can be used in place of immunotherapy.
Proteasome inhibitors act on certain proteins critical for the survival of myeloma cells.
Immunomodulatory drugs are involved in improving the immune response of the patient. They help improve the immune system's ability to detect and attack the cancer.
CAR-T cell therapy includes removing the T-cells, genetically modified, to improve their ability to detect and fight cancer cells. T-cells are white blood cells that are involved in fighting against cancer cells.
Monoclonal antibodies attach to the surface of the cancer cells.
Chemotherapy is used to destroy fast-growing cancer cells. Chemotherapy is given in cycles and is usually given through intravenous infusion. Bendamustine, cisplatin, cyclophosphamide, doxorubicin, etoposide, and melphalan are commonly used chemotherapy agents to treat multiple myeloma.
Radiation therapy is a local therapy where it treats cancer within a specific area. Sometimes it is used only to treat a single mass of myeloma cells. Radiation therapy involves targeting a specific area with high-energy rays.
Triple therapy includes the combination of drugs of three different classes.
Bone-building therapy is aimed at strengthening the bone, which includes drugs like bisphosphonates or denosumab
Stem cell transplant includes destroying the cells in bone marrow with chemotherapy, followed by adding new healthy stem cells.
Maintenance therapy includes low doses to maintain the results achieved by prior therapies. The standard drugs include lenalidomide, ixazomib or bortezomib.