Cytostatics are substances that inhibit cell growth and/or cell division. They are primarily used as part of chemotherapy for cancer. This is because cytostatic drugs attack cells that divide rapidly. This is the case with cancer cells, which multiply by uncontrolled cell division, but also with some healthy body cells. These cells include mucosal cells in the mouth and gastrointestinal tract, cells in the bone marrow, and hair cells. Cells that do not divide during treatment, on the other hand, are generally not affected by the drugs.
Cytostatic drugs inhibit cell division
Cytostatic drugs ensure that the division as well as the uncontrolled growth of tumor cells are inhibited and that the cells die. To do this, some substances incorporate errors into the DNA of the tumor cells or inhibit the copying process of the genetic material, which is essential for the cell to divide. Other cytostatic drugs influence the cell’s metabolism. The damaged or dead cells are recognized and broken down by the body’s own control mechanism. If the therapy is successful, the tumor becomes smaller or at least stops growing. However, it is not possible to tell overnight whether chemotherapy is successful or not: It usually takes a few days or even a few weeks to see whether the treatment is working. The success of the treatment is monitored at regular intervals. Treatment is considered successful when the tumor has stopped growing, has shrunk or has disappeared completely. Likewise, an improvement in the patient’s subjective well-being is also considered a success.
Various agents
Many different cytostatic drugs are available for chemotherapy. Which drug is used in each case depends on the type of cancer, among other factors. The following is a list of the most important cytostatic drugs.
Alkylants
Alkylanzien prevent the duplication of the genetic material in the tumor cells, which is mandatory for cell division. This prevents the cells from multiplying and the tumor from growing. The group of alkylanzien includes, among others, agents such as busulfan, cyclophosphamide and ifosfamide. The so-called platinum analogues are also counted among the alkylants in the broader sense. They combat tumor cells by binding with the genetic information in the tumor cells, thereby destroying them. They also inhibit those enzymes that could repair the damage caused to the DNA. Because platinum analogues can cause severe nausea, concomitant medications are usually administered. Agents in this group include cisplatin, carboplatin, and oxaliplatin.
Antibiotics
Antibiotics, like cytostatics, inhibit the growth and multiplication of cells. However, most antibiotics target cells foreign to the body. Only a few inhibit the proliferation of the body’s own cells and thus can be counted as cytostatics. These antitumor antibiotics cause breaks in the DNA of tumor cells and induce changes in the cell membrane. Since they do not only act during the cell division phase, they usually have more side effects than other cytostatic drugs. The group of antitumor antibiotics includes agents such as doxorubicin and epirubicin.
Antimetabolites
Antimetabolites destroy the genetic material of cells by inserting themselves into the DNA of cells as false building blocks. They act during cell division and have relatively few side effects compared with other cytostatic drugs. The group of antimetabolites includes agents such as:
- Methotrexate
- Fluorouracil
- Cladribine
- Fludarabine
- Tioguanine
Hormones
Strictly speaking, hormones do not belong to the cytostatic drugs. However, they can be helpful in the context of chemotherapy for those tumors whose growth is stimulated by hormones. Female sex hormones, for example, promote the growth of breast cancer, while male sex hormones promote that of prostate cancer. The use of the respective antagonists can curb the growth of the tumors. Depending on the type of cancer, for example, antiestrogens or antiandrogens are administered.
Mitosis Inhibitors
Mitosis inhibitors prevent the nuclei of tumor cells from dividing. If this process is blocked, the cells cannot multiply. Mitosis inhibitors include many plant compounds, including vinca alkaloids and taxanes.
- Vinca alkaloids: they are obtained from the periwinkle (Vinca) plant. Examples of active ingredients from this group are vinblastine and vincristine.
- Taxanes: they are obtained from yew bark. Examples of active ingredients from this group are docetaxel and paclitaxol.
Topoisomerase inhibitors
Topoisomerase inhibitors block the enzyme topoisomerase, which is what allows cells to proliferate in the first place. If the cancer cells’ topoisomerases are inhibited, the tumor cannot continue to grow. Examples of topoisomerase inhibitors include etoposide, irinotecan, and topotecan.