Regional Chemotherapy (RCT)
Here you can find answers for the following questions:
- What is regional chemotherapy (RCT)?
- What is the working principle underlying regional chemotherapy?
- What are the advantages of regional chemotherapy?
- What techniques are used in regional chemotherapy?
- For which types of cancer is regional chemotherapy especially helpful?
1. What is regional chemotherapy (RCT)?
Regional chemotherapy (RCT) is regionalized chemotherapy, that is, chemotherapy restricted to one region of the body or to one organ. Thus, medication (a cytostatic or chemotherapeutic agent) is administered into the arteries (blood vessels) which supply a specific tumour or the tumour region with blood.
In effect the tumor is isolated and targeted with specific agent or medication.
During regional chemotherapy, a greater amount of the administered cytostatic agent is taken up by the tumour in the tissues. As an outcome the effect of the drug on the tumor as more damaging.
Immediately following the treatment procedures, the blood is washed out by chemofiltration. This process removes excess medication, largely preventing side effects in the patients. Dr. Klopp and Dr. Biermann, USA, first observed and reported this outcome in 1950s.
2. What is the working principle
underlying regional chemotherapy?
Our aim in using regional chemotherapy is to severely damage the tumour while keeping side effects for the patient to a minimum. Regional chemotherapy is effective in treating what are known as “solid tumours.” However, not every type of tumour responds equally well to highly concentrated chemotherapy.
Some tumours require extremely high concentrations of the anti-tumour medication, while others show treatment effects even at lower concentrations. The rule of thumb is that to permanently damage a solid tumour, you need about six times the concentration that can be achieved using conventional chemotherapy. With a number of different RCT techniques, it is possible to reach concentrations of cytostatic agents that are between three to ten times (and in extreme cases up to eighty times) as high as those in conventional chemotherapy.
A crucial element in the success of therapy is the nature of the tumour’s blood supply. Only small concentrations of cytostatic agents can be delivered to a tumour that is poorly vascularized (perfused), even by using a direct arterial approach. Perfusion can also be destroyed or reduced by various secondary factors, such as prior surgery with scar formation or previous irradiation.
The goal of regional chemotherapy is to reduce the size of the tumour prior to surgery to such an extent that the ensuing surgical procedure can be kept as small as possible. In the best case, the tumour disappears completely even before surgery.
3. What are the advantages of
Since regional chemotherapy is always restricted to a single body region or organ, the overall effects upon the body as a whole are less, despite the intense regional effect, and fewer side effects occur. Not least, as a result of the systemic detoxification performed after each treatment using chemofiltration, in 95% of cases patients tolerate the treatment extremely well. Their quality of life is less impaired, and often, it already begins to improve quite rapidly directly after treatment. Nausea and vomiting are very rarely seen following the treatment.
4. What techniques are used
in regional chemotherapy?
We use a number of different techniques to administer RCT. They are designed in such a way as to keep the surgical interventions as minimal as possible.
I. Arterial infusion through an angiocatheter.
For arterial infusion, a catheter is inserted into an artery in the groin area under regional anaesthesia and its tip is directed into the tumour region under X-ray monitoring and placed there.
Advantage: no surgery required
Disadvantage: during treatment (3-4 days), the patient cannot get out of bed.
Illustration: Angiocatheter in the celiac trunk for regional chemotherapy of liver metastases from a carcinoid tumour of the small bowel. These metastases are so well vascularized that they can be visualized with contrast material injected into the artery.
II. Arterial infusion through a surgically implanted port catheter.
In this method, a port catheter is implanted directly into the vessel supplying the tumour by means of a surgical operation. This makes it possible to treat the tumour as often as necessary without the need for any additional surgery.
Advantage: the patient is mobile afterwards, since the arterial infusion can be performed by puncturing the port each time. The operation provides better information about the extent of the tumour.
Disadvantage: surgery and its attendant risks
Chemoembolization is employed primarily for liver tumours and metastases. In this procedure, the thinnest blood vessels (capillaries) are blocked with microparticles, and the cytostatic agent is retained in the tumour area. In addition, blocking the blood vessels deprives the tumour area of its oxygen supply.
IV. Isolated perfusion
Isolated perfusion is performed as a part of a surgical operation. In this procedure, an organ or body region is isolated using catheter systems. Then, this region is perfused with a high concentration of the cytostatic agent. Such perfusion is done through the use of an external pump.
At the same time or just prior to the procedure, the tumour can also be heated. Such procedure is called hyperthermia. In some cases, the oxygen content in the blood can be reduced after administration of the cytostatic agent. The procedure of reduction of the oxygen in the blood is called hypoxia. With some cytostatic agents, hypoxia can result in up to a tenfold increase in toxicity for the tumour.
Result: the tumour disappears more rapidly
The following organs or body parts may be perfused in isolation:
- Thorax (lungs, thoracic wall and head)
- Extremities (arm, leg)
To remove excessive amounts of chemotherapy agents from the systemic circulation we use chemofiltration after each isolated perfusion phase – the patient experiences few side effects.
5. For which types of cancer is regional chemotherapy especially helpful?
The decision to use regional chemotherapy is based on whether the treatment promises success or not. The success of this procedure depends on the sensitivity and the blood supply (vascularization) of the tumour or metastases. The types of treatment previously administered also play an important role in this decision. For example, previous surgery may disrupt or alter the blood supply of the target area due to scar formation. In other cases, intensive previous general chemotherapy could lead to the development of resistance in the tumour tissue. In turn, such resistance may be overcome by increasing the regional concentration of the cytostatic agent.
As the area of the body affected by the tumour increases, the chances of success decrease. This may happen because the total dose of cytostatic agent administered will be progressively diluted. If the chemotherapy must be distributed over a larger area, then the effective concentration at the site of the tumour will fall. As an outcome of such dilution, the RCT procedure will have lower effectiveness.
We divide the indications for ECT, as measured by the chances for success, into three groups:
I. Tumours with good response rates
- Breast cancer (Cancer of the breast and metastases)
- Tumours of the head and neck
- Stomach carcinoma
- Bladder carcinoma
- Prostate carcinoma
- Ovarian carcinoma
- Cholangiocellular carcinoma
- Anal carcinoma
- Thyroid carcinoma
- Esophageal carcinoma
- Carcinoid tumours
II. Tumours with moderate to good response rates
- Bronchial carcinoma
- Pancreatic carcinoma
- Hepatocellular carcinoma
- Soft tissue sarcomas
- Malignant melanoma
- Carcinoma of the cervix
III. Tumours with poor to moderate response rates
- Large bowel and rectal carcinoma
- Gall bladder carcinoma