Commonly used terms

We have compiled a list of terms you may come across when reading about treatments for childhood leukaemia.

Bone marrow transplantation
Bone marrow transplantation is the term previously used to describe stem cell transplantation.

The new terminology reflects the less invasive method now used to collect stem cells from the donor’s circulating blood rather than their bone marrow.

Central line
A central line, also known as a Hickman line, is a tube which is used to give chemotherapy. It goes into the chest and directly into one of the major blood vessels.

The end of the central line protrudes from the chest and is sealed off with a cap. It usually stays in place for the duration of treatment.

Having a central line avoids the needs for repeated injections as all intravenous medication can be given through the line. The line can also be used to collect blood samples which are frequently required during leukaemia treatment.

Chemotherapy
Chemotherapy is the term used to describe the drugs which a child is given to kill the leukaemia cells. These drugs may be taken orally (by mouth), intravenously (injected directly into a vein), intramuscularly (injected directly into the muscle) or intrathecally (directly into the spinal fluid via a lumbar puncture).

Chemotherapy is the basis of all leukaemia therapy and may be supplemented with radiotherapy and/or stem cell transplantation.

Clinical trials
A clinical trial is a scientific comparison of one or more treatment options to determine which offers the best outcome. Information gathered from successive trials has been one of the most important factors in the increasing survival rates for childhood leukaemia.

Most children diagnosed with leukaemia will be asked to take part in a clinical trial. Taking part is entirely voluntary and children who do not take part will receive the current standard treatment.

Donor lymphocyte infusion (DLI)
DLI is a treatment used in patients who have relapsed following a stem cell (also known as bone marrow) transplant. The procedure uses lymphocytes (white blood cells) from the same donor to boost the life-saving effects of the original transplant.

Hickman line
Hickman line is another term for ‘central line’ – see above.

Lumbar puncture
A lumbar puncture is used to inject drugs directly into the patient’s spinal fluid.

Minimal residual disease
Every child will have some leukaemia cells remaining in their bone marrow when they achieve remission. This is known as minimal residual disease (MRD).Read more about minimal residual disease

Portacath
A portacath is a small chamber or reservoir that sits under the patient's skin at the end of their central line (see central line above). Chemotherapy is given by inserting a needle into the chamber. The portacath stays in place for as long as treatment is needed.

The main advantage of a Portacath is that it is not visible on the outside of the body. There is no tube coming out of the chest, as there is with a central line. But some people prefer a central line because they don't like having a needle put in each time they need treatment. It is possible to have the area over the Portacath numbed with a local anaesthetic cream before the needle is put in.

Radiotherapy
Some children will require doses of radiation to ensure that all leukaemia cells have been killed. It is usually only used when the patient is thought to be at risk of having leukaemia cells in the fluid which surrounds their brain and spinal cord.

Radiotherapy is also used in children requiring stem cell transplantation to destroy their existing bone marrow prior to transplantation.

Relapse
A child is said to be in relapse if the leukaemia returns once they have achieved remission.

Remission
A child is said to have achieved remission when the majority of the leukaemia cells in their bone marrow have been destroyed and their bone marrow can resume normal function. This usually happens within the first few weeks of treatment.

Stem cell transplantation
Stem cell transplantation is used to replace a child’s damaged bone marrow with healthy new bone marrow. The new stem cells may come from a donor or they may be the patient’s own cells, harvested before treatment.

Read more about stem cell transplantation.

Photo: Lodish et al. Molecular Cell Biology, 5th Ed, WH Freeman