Types of Blood Cancer

'Blood cancer' is the umbrella term used for a variety of malignant diseases of the blood-forming (hematopoietic) system. A distinction is made between two kinds, depending on how they originated: leukemias and lymphomas. Leukemias begin in the bone marrow, whereas lymphomas start in the lymphatic system.

All blood cancers involve the degeneration of certain blood cells, which multiply uncontrollably and suppress the healthy blood-forming system. This prevents the blood from performing vital functions, such as fighting infections, transporting oxygen, or stopping bleeding.

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FAQs

The three most common forms of blood cancer are:

Leukemia

Leukemia is a blood cancer that develops when normal blood cells change and grow uncontrollably. There are four main types named according to the cells affected (myeloblasts, lymphocytes) and whether the disease starts with mature or immature cells (chronic, acute).

Lymphoma

Lymphoma is the name for a group of blood cancers that develop in the lymphatic system. The two main types are Hodgkin lymphoma (generally starts in blood and bone marrow) and non-Hodgkin lymphoma (generally starts in lymph node and lymphatic tissue.)

Multiple Myeloma

Multiple myeloma starts in the bone marrow when plasma cells begin to grow uncontrollably. As the cells grow, they compromise the immune system and impair the production and function of white and red blood cells causing bone disease, organ damage and anemia among other conditions.

Symptoms and indications

How do you recognize leukemia?

There are no specific indications for diagnosing blood cancer or leukemias, as all the symptoms can manifest with other conditions as well. They include spontaneous bleeding, fever, swollen lymph nodes, fatigue or paleness.

However, doctors are able to recognize the symptoms in the overall context and if they suspect that someone has a serious condition such as blood cancer will perform tests accordingly.

Causes and risk factors

Prevention

There are no known basic measures that can prevent someone from getting blood cancer and unlike colon or breast cancer, blood cancer cannot be identified by precautionary or early-detection screening. However, we do know that radioactive radiation can cause blood cancer, as can various chemical substances, such as benzenes and, less commonly, certain chemotherapeutics. Genetic predisposition and infection with certain viruses are also risk factors.

Radioactive radiation

One of the most widely known risk factors is ionizing radiation in high doses. Ionizing radiation can cause genetic changes in stem cells, which are responsible for blood cell formation. The higher the dose, the greater the risk of developing blood cancer. Over-exposure to medical X-rays or radiotherapy can be a factor in the disease.

Chemical substances

Certain chemical substances, such as herbicides, insecticides, and some solvents (e.g. benzene), are considered definite risk factors for developing blood cancer. The disease can also be as a result of some drugs used in conjunction with chemotherapy to treat other types of cancer (cytostatics).

Genetic predisposition

Certain pre-existing hereditary conditions can significantly increase the risk of developing blood cancer. People with Down syndrome, for instance, have a considerably greater risk of developing acute myeloid leukemia (AML), as do people from families with a history of multiple malignant diseases.

Infection with certain viruses

The human T-lymphotropic virus (HTLV) affects human T cells. In 1-2 percent of cases, it can lead to the onset of what is known as adult T-cell leukemia. The virus is predominantly found in the region around Japan, so the risk of infection is extremely low in Europe.

Apart from these factors, there is no clear evidence as to why people develop blood cancer – which is why there are no known ways of preventing it. So if you are unfortunately diagnosed with blood cancer, please don’t torture yourself by thinking about which supposedly better lifestyle choices might have prevented you from getting it!

Testing

Sonography

A sonography is a diagnostic medical test using ultrasound. Abdominal sonography is used to examine the internal organs, such as the liver, spleen, kidneys and intestines. Ultrasound can also be used to check heart function (echocardiogram) and changes in the lymph nodes. A sonogram has the advantage that there is no radiation risk or pain.

X-rays

In most cases, the lungs will be X-rayed in addition to other tests, to make sure there is no chest infection. With lymphomas, a chest X-ray also allows the doctors to check for potential heart or lung tumors.

CT scan

A CT scan (Computer Tomography), or CAT scan, is a computer-assisted X-ray examination that creates detailed cross-sectional images of the body. The scan (computer tomogram) shows the different types of tissue in various shades of gray, depending on their density. It is considerably more detailed than a regular X-ray image and allows enlarged lymph nodes, for example, to be located and assessed as accurately as possible.

MRI scan

MRI (Magnetic Resonance Imaging) is another computer-assisted imaging method, this time using magnetic fields and radio waves to produce detailed sectional images from inside the human body. The images can capture structures right down to the smallest detail. That is why MRI is often used to examine the lymph nodes, spinal cord and brain. Unlike with CT, MRI scans do not involve radiation exposure. However, because they use magnetic fields, they cannot be used on patients with metal parts on or in their bodies, such as pacemakers.

PET scan

In a PET (Positron Emission Tomography) scan, a radioactive tracer drug is administered through the veins. A different tracer is used for each organ. As it accumulates in the target organ, it is made visible via a special camera. Tumors have a better blood supply, so they attract more of the tracer. PET scans are mainly used for lymphomas, to assess the precise spread and the patient’s response to treatment.

Types of treatment

Chemotherapy as the chance of a cure

Most types of blood cancer can first be treated with chemotherapy, the aim of which is to simply destroy the cancer cells. Other forms of treatment can be used as well, such as radiation or antibody therapies, or a blood stem cell transplant.

Blood stem cell donation as the last chance

For many patients, a blood stem cell donation is their last chance to beat blood cancer. These patients need a matching donor whose tissue characteristics (HLA characteristics) should match those of the patient 100 percent, if possible. To prepare for the transplant, the patient undergoes chemotherapy to suppress their own immune system, which helps to ensure the body does not reject the donation. After the transplant, the immune system gradually rebuilds itself.

Chemotherapy

With chemotherapy, the patient is given so-called cytostatic drugs to inhibit cell division and destroy the cancer cells. The treatment is performed in a hospital over several cycles, with drugs administered on one or more days followed by a break for the body to recover before the next cycle begins. The drugs can be given in the form of tablets, an injection or an infusion.

Radiation therapy

Radiation therapy is used to specifically target tumors. The radiation is similar to that in X-rays but considerably higher-energy, which works by damaging the genetic makeup of the cancer cells. This stops them from dividing even further and kills them off. The process also affects healthy cells, but these can regenerate later on.

Antibody therapy

Antibodies are generated by immune cells in the body. They work by recognizing surface structures (antigens) of pathogens and attaching themselves to them. Any cells that are flagged in this way are identified by other immune cells as hostile and destroyed. More and more blood cancers can now be treated with artificially produced antibodies — especially non-Hodgkin lymphoma (NHL), but also chronic lymphocytic leukemia (CLL). They work on the basis of a 'lock and key' principle: the available antibodies are the key and work only on cancer cells with a matching lock, or antigen. If lock and key don’t match, the therapy will not work.

Blood stem cell transplantation

For many blood cancers, transplanting healthy blood stem cells is one possible form of treatment — and often the only chance of a cure. Whether or not a patient can undergo a blood stem cell transplant and what method is used, depends on numerous factors including their particular diagnosis, age and state of health.

There are three different types of transplant: autologous, allogeneic, and syngeneic.

An autologous blood stem cell transplant uses the patient’s own stem cells, which are harvested from the blood and cleared of cancer cells. The patient receives chemotherapy, and their stem cells are returned to the body.

An allogeneic stem cell transplant uses the blood stem cells of a related or unrelated donor with the closest possible match of tissue characteristics.

A syngeneic transplant is the rarest form of stem cell transplant, as it involves using the cells of identical twins.

Matching donor

One crucial factor in the success of a blood stem cell transplant is the degree of match between the tissue characteristics (HLA) of donor and patient. Tissue characteristics are protein structures on the surfaces of all cells and occur in different combinations in every individual, much like fingerprints. The immune system recognizes from these protein structures whether or not a cell belongs to its own body. If it does, the cell is left intact. If not, the immune system destroys it. That is why it is essential to find a donor whose HLA characteristics match the patient’s as closely as possible. This way, the new immune system that develops from the donor’s stem cells will accept the patient’s own cells.

Tissue characteristics are inherited, which means the best chance of finding a matching donor for the patient is within their own family. Parents are normally only haploidentical, or ‘half-matching’ donors, as a child inherits half of its tissue characteristics from the mother and half from the father. The highest probability of a match is between siblings, which is why they are the first family members that are tested as potential donors.

If there are no matching donors in the patient’s family, the search continues with an attempt to find a matching unrelated donor on stem cell registries around the world. Over 36 million people have now chosen to register as potential blood stem cell donors worldwide and over 10 million of them are registered with DKMS in seven different countries. The details of all registered DKMS donors are pseudonymised and collated centrally, at the German National Bone Marrow Donor Registry (ZKRD) in Ulm. If no suitable donor is found there, the search is extended internationally.

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