Today a variety of drug therapies are available, e.g. chemotherapy, targeted therapy or immunotherapy. They are based on different mechanisms of action and can be adapted to the patient’s individual situation.
A number of kinds of chemotherapy are available for the treatment of cancer. Different active substances or combinations of active substances are used depending on the kind of cancer involved. These are known as cytostatic drugs. They attack the genetic material (DNA) of cells and obstruct or prevent cell division. As tumour cells divide particularly frequently and rapidly, they are particularly vulnerable to the effect of cytostatic drugs.
The relevant active substance or combination of active substances is administered either as an infusion or an injection. Some active substances can also be taken in the form of tablets. Regardless of the method of administration, cytostatic drugs are distributed throughout the body in the bloodstream. This is why these forms of chemotherapy are described as systemic treatments. However, it is not only the function of rapidly dividing cancer cells but also that of frequently dividing healthy cells that is disrupted. These include cells in mucous membranes and at hair roots, for example, and this can cause temporary side effects. However, many kinds of chemotherapy are more tolerable now than in the past and considerable improvements have also been made in the treatment of side effects. In addition to systemic chemotherapy, local chemotherapy can be used in bladder cancer, for example. In this case, the cytostatic drugs are flushed into the bladder through a catheter.
Patients with many kinds of cancer can now be treated with targeted therapies. What distinguishes these treatments is that tumour cells are targeted specifically and healthy tissue is largely spared. In most cases, however, targeted therapies are suitable only in cases where the tumour cells have certain characteristics.
The required proof is obtained from the pathological findings based on a sample of the tumour tissue. Such characteristics include specific protein molecules (e.g. receptors) that transmit signals to the inside of the cell.
The therapy involves administration of antibodies that are produced using biotechnology. These antibodies bind to these precise receptors or other defined structures on the tumour cells. This binding and the accompanying blockade obstructs the division of the cancer cells and – depending on the active substance – also steers the body's immune defence towards the tumour cells. Targeted therapies also include the use of drugs called tyrosine kinase inhibitors. These are medicines which stop signal transmission to the inside of tumour cells and, in this way, slow down the division and growth of cancer cells.
Immunotherapy is a relatively new treatment that has rapidly established itself in the field of cancer treatment. It does not target the tumour itself but (re)activates the body's immune system to fight the cancer.
The immune system normally recognises tumour cells and attacks them. Certain immune system cells (T-cells) play an important role in this. However, cancer cells can develop the ability to evade attack by these T-cells. They are able to do this by triggering a natural control mechanism of the immune cells that slows down their activity. The purpose of the mechanism is actually to prevent inappropriate immune responses to healthy and "normal" body cells.
The purpose of the mechanism is actually to prevent inappropriate immune responses to healthy and "normal" body cells. The molecular switch that triggers immune cell deactivation is called a "checkpoint". If the affected T-cells are now switched off, they no longer attack the cancer cells, which are able to continue multiplying. However, this blockade – triggered by the tumour – can also be reversed by immunotherapy using drugs called checkpoint inhibitors.
Thanks to the active substances they contain (therapeutic antibodies), the body's immune defence is reactivated and the T-cells are once again able to recognise the tumour as such and the immune system is able to fight it.
Proof of a particular tumour characteristic may be a prerequisite for immunotherapy, depending on the disease. Due to the influence of the treatment on the immune system (reactivation), particular vigilance for any immune system overreactions and the associated side effects is required during therapy. Nevertheless, immunotherapies are better tolerated, overall, than the chemotherapies used to treat the respective kinds of cancer in the past.