How myeloma is related to the bone marrow

Myeloma is a cancer of plasma cells, which are normally found in the bone marrow.

Bone marrow and blood cells

The bone marrow is a spongy material that fills the middle of some bones and produces cells called stem cells. These are immature cells that develop into the three different types of blood cells:

• red blood cells, which carry oxygen to all the cells in the body
• white blood cells, which are essential for fighting infection
• platelets, which help the blood to clot and so control bleeding.

Bone and bone marrow

Plasma cells

Plasma cells are one of several types of white blood cell, all of which work together to protect the body against infection. Plasma cells produce special proteins known as antibodies or immunoglobulins. These antibodies circulate in the blood ready to attack any viruses and bacteria that may be present in the body.

If an infection occurs, more plasma cells are produced, creating more antibodies to attack whatever is causing the infection.

What is myeloma?

Myeloma is also known as multiple myeloma or myelomatosis.

Blood cells look and work differently, but they all repair and reproduce themselves in the same way. Normally, new cells are produced to replace old, worn-out cells in an orderly, controlled way. However, in myeloma the process gets out of control and large numbers of abnormal plasma cells – myeloma cells – are produced. These fill up the bone marrow and interfere with production of normal white cells, red cells and platelets.

The myeloma cells usually produce a large amount of one type of abnormal antibody. This is known as a paraprotein or M protein. This paraprotein cannot fight infection effectively and often reduces the production of normal antibodies.

Myeloma cells have the ability to spread throughout the bone marrow and into the hard outer casing of the bone. Some, or many, areas of bone may be affected. Myeloma can cause thinning of the outer bone and bone pain.

Myeloma usually occurs in middle-aged and older people. It is unusual before the age of 50 and very rare in people younger than 40.

Myeloma is one type of disorder of the plasma cells. Some other conditions of the plasma cells can develop into myeloma but may not necessarily do so. The two most common of these are monoclonal gammopathy of uncertain significance (MGUS) and smouldering myeloma (also known as indolent or asymptomatic myeloma). If you are diagnosed with either of these conditions, you will be monitored with blood tests, but may not need to have any treatment unless the condition progresses.

Sometimes abnormal plasma cells are found in a bone in only one area of the body. This condition is known as a solitary plasmacytoma. It is treated with radiotherapy. Some people with solitary plasmacytoma may go on to develop multiple myeloma, so you will be regularly monitored with blood tests.

What is cancer?

The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells.

Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, cells divide in an orderly and controlled manner. If for some reason the process gets out of control, the cells carry on dividing, developing into a lump which is called a tumour.

Tumours can be either benign or malignant. Cancer is the name given to a malignant tumour. Doctors can tell if a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy.

In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, if they continue to grow at the original site, they may cause a problem by pressing on the surrounding organs.

A malignant tumour consists of cancer cells that have the ability to spread beyond the original area. If the tumour is left untreated, it may spread into and destroy surrounding tissue. Sometimes cells break away from the original (primary) cancer. They may spread to other organs in the body through the bloodstream or lymphatic system.

The lymphatic system is part of the immune system - the body's natural defence against infection and disease. It is a complex system made up of organs, such as bone marrow, the thymus, the spleen, and lymph nodes. The lymph nodes (or glands) throughout the body are connected by a network of tiny lymphatic ducts.

When the cancer cells reach a new area they may go on dividing and form a new tumour. This is known as a secondary cancer or metastasis.

It is important to realise that cancer is not a single disease with a single type of treatment. There are more than 200 different kinds of cancer, each with its own name and treatment.

Types of cancer

Carcinomas

The majority of cancers, about 85% (85 in a 100), are carcinomas. They start in the epithelium, which is the covering (or lining) of organs and of the body (the skin). The common forms of breast, lung, prostate and bowel cancer are all carcinomas.

Carcinomas are named after the type of epithelial cell that they started in and the part of the body that is affected. There are four different types of epithelial cells:

• squamous cells - that line different parts of the body, such as the mouth, gullet (oesophagus), and the airways
• adeno cells - form the lining of all the glands in the body and can be found in organs such as the stomach, ovaries, kidneys and prostate
• transitional cells - are only found in the lining of the bladder and parts of the urinary system
• basal cells - that are found in one of the layers of the skin.

A cancer that starts in squamous cells is called a squamous cell carcinoma. A cancer that starts in glandular cells is called an adenocarcinoma. Cancers that start in transitional cells are transitional cell carcinomas, and those that start in basal cells are basal cell carcinomas.

Leukaemias and lymphomas

These occur in the tissues where white blood cells (which fight infection in the body) are formed, i.e. the bone marrow and lymphatic system. Leukaemia and lymphoma are quite rare and make up about 6.5% (6.5 in 100) of all cancers.

Sarcomas

Sarcomas are very rare. They are a group of cancers that form in the connective or supportive tissues of the body such as muscle, bone and fatty tissue. They account for less than 1% (1 in 100) of cancers.

Sarcomas are split into two main types:

• bone sarcomas - that are found in the bones
• soft tissue sarcomas - that develop in the other supportive tissues of the body.

Others forms of cancer

Brain tumours and other very rare forms of cancer make up the remainder of cancers.

Causes of myeloma

Each year, approximately 3700 people in the UK are diagnosed with myeloma.

Although the causes of myeloma are unknown, research is going on all the time into the possible causes of the disease. Myeloma, like other cancers, is not infectious and cannot be passed on to other people.