Repairing veins after chemotherapy

Effect and side effects of chemotherapy

The three main forms of treatment for cancer are surgery, drug therapy (including chemotherapy) and radiation therapy. Which treatments are used is decided individually in each case and is primarily dependent on the type of tumor and the stage of the disease.

Any previous or concomitant illnesses, general state of health and age are also included in the individual therapy planning.

The following text is intended to inform you about the basics of chemotherapy and to help you better understand how it works and how it is carried out.

How does chemotherapy work?

The individual drugs that are used for chemotherapy in cancer diseases are summarized under the term "cytostatics". This term roughly translates as “cell stopper” - and thus already describes their function. The task of cytostatics is to inhibit the growth of cancer cells and thereby cause tumors to regress.

Normally the growth of cells is strictly regulated. In healthy cells only as many cell divisions take place as are necessary for the maintenance and function of the tissue. Cancer cells can escape the normal control mechanisms of the cell cycle, divide in an uncontrolled manner and grow unhindered - a tumor develops.

Cytostatics make use of this characteristic of cancer cells: They preferentially attack cells that divide particularly frequently and grow quickly. They influence various processes that are important for cell division and disrupt the course of the cell cycle in different ways.

Alkylating substances

Some drugs can form chemical bonds with the genetic material of the cancer cell (DNA). The incorporation of so-called alkyl groups leads to cross-connections or cleavage of DNA strands, which means that the cell can no longer divide. This active group includes nitrogen mustard compounds, nitroso urea compounds and platinum compounds.

Antimetabolites

So-called antimetabolites are built into the DNA as false building blocks during the replication of the cancer cell's DNA. This destroys the genetic information in the relevant places and the cell can no longer divide. This group of cytostatic agents includes the folic acid antagonists, the purine analogs and the pyrimidine analogs.

Mitosis inhibitors (spindle poisons)

These active ingredients prevent cells from dividing by blocking the development of what is known as the spindle apparatus. During a cell cycle, the genetic material of a cell is doubled and, after cell division, is divided between the two daughter cells that have been created. If the development of the spindle apparatus is blocked, this process cannot take place and the cell cannot divide any further. Medicines from the vinca alkaloids and taxanes group work in this way.

Topoisomerase inhibitors

These active ingredients intervene in the body's own repair mechanisms of the cells. Every cell has certain enzymes that can repair damage in the DNA and thus ensure the survival of the cell. So-called topoisomerase inhibitors block these enzymes in cancer cells, which means that damage can no longer be adequately repaired and the cell dies.

Cytostatic antibiotics

In the narrower sense, antibiotics are usually drugs that are directed against bacteria. But there are also antibiotics that can attack tumor cells via similar mechanisms of action. Some bind to the DNA and block the replication of the DNA during cell division, others cause strand breaks in the DNA and thus lead to cell death, and still others influence the metabolism of the cancer cell. These antitumor antibiotics include the anthracyclines and the actinomycins.

Individual active ingredients from different groups are often combined with one another in order to increase the therapeutic effect.

How is chemotherapy performed?

Most chemotherapies are carried out in hospitals with specialized oncological departments, wards, day clinics or outpatient departments.

At the beginning of therapy, a short stay in hospital of one or a few days may be necessary in order to check tolerability and any side effects that may occur. In most cases, however, the treatments can be continued on an outpatient basis.

The form in which the chemotherapy is administered depends primarily on the type of cancer and the particular cytostatic agent used. Most patients receive chemotherapy via infusions into the vein, injections into the vein, tablets or capsules for oral ingestion, and ointments or lotions for some skin tumors are also possible. If frequent administrations into the vein are necessary over a longer period of time, a reservoir system (port catheter, port-a-cath, port) is implanted in some cases. A small chamber made of sterile material is inserted under the skin below the collarbone, which is connected to a large vein via a tube. With the help of a special needle, the chemotherapy can be administered into this chamber - this means that a new venous access does not have to be established for each treatment. The port catheter is implanted as part of a minor surgical procedure and does not usually lead to any restrictions in everyday life.

The therapy runs according to a fixed time schedule. The frequency and duration of the treatments depend on the type of cancer and the treatment goal, as well as which drug is used and how long it works in the body. In principle, chemotherapy can be given daily, weekly or monthly.

Treatment breaks are inserted between the phases of the treatment. The period from the beginning of one treatment phase to the beginning of the next treatment phase is called cycle and often lasts three or four weeks. The administration of chemotherapy in cycles has the following background: All cells, including cancer cells, are alternately in phases of cell division and rest. Cytostatics only act on cells that are currently in the dividing phase; cells in the resting phase are not attacked. This means that not all cancer cells are reached during treatment. The chemotherapy must therefore be carried out in a specific time sequence in order to destroy as many cancer cells as possible. In addition, healthy cells that have also been attacked by chemotherapy have time to recover during the treatment breaks. After about two to three therapy cycles, check-ups are carried out to check the success of the treatment.

Chemotherapy is generally used systemically, which means that the drugs reach every part of the body via the bloodstream and are thus supposed to reach every cell. In this way, cancer cells that have detached from the tumor and are scattered around the body can also be combated, which can prevent the formation of daughter tumors (metastases). In rare cases, chemotherapy is limited to one organ or part of the body; this is known as local or regional therapy. For example, the cytostatic agent is administered directly into an artery that supplies the tumor directly. However, this form of administration is only suitable for a few types of tumor in certain situations.

What does adjuvant, neoadjuvant or curative chemotherapy mean?

Depending on the type and stage of the tumor, chemotherapy can be used to reduce the likelihood of the tumor returning. In this case, one speaks of a preventive, so-called, carried out following surgical removal of the tumor adjuvant chemotherapy.

In the case of some tumor diseases that are present in a localized stage (e.g. breast cancer, malignant bone tumors), chemotherapy is administered prior to the surgical removal of the tumor. One then speaks of a so-called neoadjuvant chemotherapy, with the aim of reducing the size of the tumor before the operation and thereby achieving better operability, but also to improve the overall chances of recovery.

There are some tumor diseases (e.g. testicular tumors, but also some forms of blood cancer / leukemia and lymph gland cancer / lymphoma), in which, even in the metastatic or advanced stage, there is a chance of completely relieving the patient of his tumor disease by administering chemotherapy heal. In this case one speaks of a so-called curative chemotherapy.

What does palliative chemotherapy mean?

Unfortunately, there are still several metastatic tumors that cannot be cured. However, there is often the possibility of using chemotherapy to slow down the course of the disease, that is, to suppress the tumor disease at least temporarily for a longer period of time or to inhibit further progression and alleviate the tumor-related symptoms. This is called chemotherapy with a palliative goal (palliative chemotherapy).

The respective sequence of the use of chemotherapy or required operations or radiation therapy is determined individually for each disease situation according to interdisciplinary agreement, depending on the type of tumor and stage.

What side effects can chemotherapy have?

Cytostatics attack cells in which a particularly large number of cell divisions take place - these are primarily cancer cells. However, some healthy cell types also divide relatively quickly, such as cells of the mucous membranes and skin, hair, the blood-forming system or the digestive tract. These tissues are also attacked by cytostatics, which results in the typical side effects:

Not all possible side effects occur in every patient. Tolerance varies from person to person and also depends on the drug used and the dosage. Before starting therapy, talk to your doctor about what side effects to expect and ask him about ways to alleviate them. It can also be helpful to keep a complaint diary during the treatment, in which you record which side effects occur and when. This is how your doctor can support you individually. In any case, the benefits and side effects of the therapy should be carefully discussed with the doctor, weighed against each other and personal wishes should be included in the decision for or against therapy.

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Authors:
Dr. med. Kerstin Lehermayr
Medical review:
Univ.Prof. Dr. Hellmut Samonigg
Editorial editing:
Dr. med. Stefanie Sperlich

Updated on:
swell

Homepage of the German Cancer Research Center - Cancer Information Service; www.krebsinformationsdienst.de/verarbeitung/chemotherapie.php (accessed in December 2013)

Homepage of the German Cancer Society (DKG); https://www.krebsgesellschaft.de/onko-internetportal/basis-informationen-krebs/therapieformen/chemotherapie.html (accessed in December 2013)

Patient information from the Austrian Cancer Aid: chemotherapy for cancer; www.krebshilfe.net/information/therapie/chemotherapie/ (accessed in December 2013)