Synonyms in the broadest sense
Radiation therapy, tumour therapy, breast cancer Chemotherapy is the drug treatment of a cancerous disease (tumour disease) that affects the entire body (systemic effect). The drugs used are so-called cytostatics (Greek from cyto= cell and static= stop), which aim to destroy or, if this is no longer possible, to reduce the size of the tumour. The point of attack of chemotherapy is the division phase of the tumour cells, which due to their uncontrolled growth they pass through very often, much more often than most healthy cells.
However, the use of chemotherapy also damages healthy cells, resulting in the numerous unavoidable side effects of chemotherapy. In order to provide the patient with an optimal therapy, chemotherapy is often combined with radiation or surgery to improve the outcome of the tumor treatment. PAUL EHRLICH originally coined the term “chemotherapy” around 1906 and meant the drug treatment of an infectious disease.
Today, we are much more likely to call the therapeutic agents used for an infection with bacteria antibiotics and leave the term “chemotherapy” to the treatment of a cancer disease. Chemotherapy or cytostatic drugs prevent the tumour cells from dividing and thus from growing. Since tumour cells divide much more often than most healthy body cells, they are much more sensitive to chemotherapy.
This principle is what makes a selective fight against the tumour cells possible. In order to better understand the mode of action of cytostatic drugs, we want to take a closer look at the division cycle of a cell. In order to turn one cell into two, the entire kit of a cell must first be doubled.
This involves doubling both the cell plasma with its components (enzymes, proteins) and the cell nucleus with the genetic information, the DNA. This phase is called interphase. The actual division is called mitosis.
Here, the DNA, packed into so-called chromosomes, is distributed to two cells, so that 2 identical daughter cells are then formed. Mitosis is the main target of the cytostatic drugs, which now want to prevent the division of the tumour cell at different points: Further details are given in the section on chemotherapy substances. Cytostatic drugs therefore intervene in the division process and metabolism of the cells, which also takes place in normal cells.
Thus, chemotherapy is not only cancer-specific, i.e. it does not exclusively attack tumour cells. Nevertheless, it mainly kills cancer cells as they behave atypically and waste their energy mainly on division. They have forgotten their original function, such as that of skin cells, which provide protection against harmful external factors.
In this context one speaks of cancer cells not being differentiated enough. However, there are also cells in our body that naturally divide often. These include the hair root cells (our hair would grow constantly if we did not cut it.
. ),the mucous membranes in the mouth and intestines and the haematopoietic cells in the bone marrow! Especially these are also attacked by chemotherapy.
This results in the unfortunately unavoidable side effects. – The most vulnerable part of a cell is the DNA (it is the “brain of a cell”, without it nothing works). If it is destroyed or put out of action, the cell is practically dead.
One way to achieve this is to simply smuggle in the wrong building block during the production of a second, identical DNA, which leads to a break in the DNA strand. Tumour cells can only correct this mistake poorly or not at all, since they usually lack the repair mechanism for this. As a result, the cell triggers the self-destruction mechanism (apoptosis).
- In order to separate the newly produced DNA from the old one, the cell needs an apparatus (the mitotic spindle), which some cytostatic drugs target in order to prevent division. There are also cytostatic drugs that act on the metabolism of a tumour cell instead of on division. Unfortunately, chemotherapy cannot guarantee success because not all cancers are the same.
There are countless different types of cancer, each of which is divided into many subtypes. In most cases, the histological examination of the tumours is the only method to assign them to a specific cancer. Each type of cancer reacts differently to chemotherapy; it is either sensitive, i.e.
it responds to chemotherapy, or it is resistant, i.e. chemotherapy has no effect. Even the same cancer may or may not be cured by the same chemotherapy in two people. But to find out which chemotherapy works for which type of cancer, different options have been tested over the years in so-called studies.
Based on the results of these studies, the current therapy standards are being developed! In principle, chemotherapy can only work if the dose, duration and frequency are right. However, the dose cannot be chosen arbitrarily high, as vital organs can be damaged.
In order to increase the chance of successfully destroying the tumour cells, a combination of several chemotherapy drugs is often chosen which complement each other in their effect and thus cause maximum damage to the tumour cells. In all cancer treatments it is important to talk to the doctor about the benefits, but also about the risks of the respective chemotherapy and to weigh them up! Radiation therapy cannot always cure the cancer.
Nevertheless, in such cases it is advisable to undergo radiotherapy, although a cure is impossible. That is why we distinguish between different objectives: Here, radiotherapy is intended to defeat cancer. It is assumed that cancer patients are cured after radiotherapy (very often this approach can be followed for cancers that are distributed throughout the body via the bloodstream, such as leukemia).
If radiotherapy is combined with surgery or radiotherapy, a distinction is made between the neoadjuvant and the adjuvant form: Apart from before or after an operation, radiotherapy can also be given in parallel to radiation therapy. In cases of advanced cancer, where metastases are found in other organs (for example in the liver) of the tumour in addition to the original site of origin of the tumour (primary tumour), it is usually impossible to cure the patient (however, according to current knowledge, a metastasis does not necessarily mean that there is no chance of recovery in this situation). In these cases, the main purpose of chemotherapy is to make the patient’s remaining time as painless as possible.
Tumour patients are in pain because the tumour is permanently growing and can thus press on adjacent structures or, as in the case of bone tumours, make them unstable. This can improve the patient’s quality of life and life expectancy. Ultimately, however, it is up to the patient to decide which type of radiotherapy to choose.
Depending on the patient’s general condition, a potentially curable tumour may still not be treated because it would be too stressful for the patient and he or she would like to avoid the strains of curative radiotherapy (which is much more aggressive). – When we speak of neoadjuvant radiotherapy, we mean preparatory radiotherapy, which takes place before an operation. Its aim is to reduce the size of the tumour in order to make the operation easier or to make it possible in the first place.
The surgeon can now preserve as much of the healthy tissue as possible and minimize the risk of the operation. – In contrast, adjuvant radiotherapy (adjuvant= supportive) is carried out after an operation or radiation. This is necessary because although the visible tumour has been removed after surgery, it is not always 100% certain that no tumour cells have remained (R1 resection).
It is hoped that the last tumour cells will be caught and removed by a subsequent radiotherapy. In this way, one can try to prevent the tumour from erupting again; in some cases, one remaining tumour cell may be enough to trigger a relapse. In addition, tumour cells can often be found outside the solid tumour (for example in the lymph nodes), which may not have been reached by surgery. Since radiotherapy is a systemic therapy, it finds and destroys tumour cells throughout the body.
