Convection Enhanced Delivery (CED) is a relatively new technique for delivering chemotherapy drugs directly into brain (and other) tumours.
CED's ability to bypass the blood-brain barrier - the membrane that controls which substances can pass from the blood into the brain - has resulted in increasing interest in this technique. This is particularly for high grade tumours that cannot be operated on due to their location, or cannot be removed completely. This includes brain tumours such as DIPG (Diffuse Intrinsic Pontine Glioma) in children.
CED involves an operation to implant up to 4 very narrow catheters (hollow tubes) into the brain. The chemotherapy drugs are delivered through these, directly into the tumour.
The blood-brain barrier then becomes an advantage, as it helps to keep the drugs within the brain.
In addition, as the drugs do not get into the blood system, the risk of having any of the side-effects associated with chemotherapy, such as hair loss and nausea, is low.
More research is being carried out to improve the technology of the catheters (tubes) and the drugs used. other aspects under review, are using the technique to give other possible treatment agents, such as antibodies and immunotoxins.
CED for the treatment of DIPG is receiving interest because the tumour is compact and treatment options are limited. (Surgery to remove the tumour is often not an option, due to the dangers of operating on a critical part of the brain. Standard chemotherapy has been found to be ineffective.)
Standard treatment for DIPG is radiotherapy, but this can cause long-term effects, particularly if given to children under 3 years.
A technique, such as CED, that can avoid some of these effects is therefore creating interest.
Currently in the UK, the Bristol Royal Hospital for Children, under Professor Steven Gill, is carrying out clinical trials using the technique to treat children with DIPG.
Similarly, the private Harley Street Clinic Children's Hospital in London is using CED to treat children with DIPG.
It is important to note that the operation is expensive. As a result, operations carried out so far have been funded privately or through fund-raising.