The Different Types of Chemotherapy
There are many different types of chemotherapy. Each of them is chosen based on the cancer to be treated and the patient’s condition. In this article, we explain the most common forms of presentation and the pharmacological agents used in chemotherapy.
Chemotherapy, as you probably know, is one of the most commonly used treatments for cancer. It encompasses a wide variety of drugs, meaning that there are many different types of chemotherapy.
The goal of this treatment is to destroy cancer cells in order to cure the disease. However, all types of chemotherapy affect both cancer cells and healthy ones, meaning that they cause severe side effects.
Throughout this article, we’ll explain the different types of chemotherapy that exist and their main characteristics.
Alkylating agents reach their highest level of activity during the resting phase and aren’t specific to cell cycles. In turn, medical professionals can indicate different types of chemotherapy treatments:
- Firstly, mustard gas derivatives. Such as cyclophosphamide, for example.
- Secondly, ethylenimines. Hexamethylmelamine is one of them.
- Hydrazines and triazines. Such as altretamine and procarbazine, among others.
- Nitrosoureas. They’re unique because, unlike most types of chemotherapy treatments, they can cross the blood-brain barrier, which is the membrane that protects the brain. Thus, they’re useful in the treatment of brain tumors.
- Finally, metal salts.
This is a type of chemotherapy that comes from certain plants. For example, vinca alkaloids are produced from the periwinkle plant or Catharanthus rosea. This group also includes taxanes, made from the bark of the Pacific Yew tree.
All plant alkaloid chemotherapy drugs, unlike the previous group, are specific to cell cycles. This means that they attack cells depending on the phase of division they’re in. Besides vinca alkaloids and taxanes, podophyllotoxins and camptothecin analogs also belong to this group.
This is another type of chemotherapy that comes from natural substances. Instead of coming from plants, this chemotherapy comes from a species of the soil fungus Streptomyces.
Antitumor antibiotics exert their effect on cancer cells in different phases of the cell cycle, and not at a specific time, as the types we mentioned above. Here are some of the most common forms of presentation:
- Anthracyclines. Such as doxorubicin or epirubicin. These drugs have long-term cardiotoxic effects.
- Chromomycins. Dactinomycin, for example.
This is a type of chemotherapy that’s very similar to the natural molecules found in cells. Thus, when the cells incorporate these substances into cellular metabolism, they’re able to block cell division.
Antimetabolites are classified according to the substances they interfere with:
- Folic acid antagonists. Methotrexate.
- Pyrimidine antagonists. 5-fluorouracil or capecitabine.
- Purine antagonists. 6-Mercaptopurine.
- Adenosine deaminase inhibitors. Cladribine, fludarabine, nelarabine, and pentostatin.
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These are drugs that owe their effect to their ability to interfere with the action of topoisomerase enzymes (both I and II). These enzymes are responsible for manipulating DNA structure, which is necessary for replication. Two examples of these drugs are irinotecan or etoposide.
As the name of this group indicates, it includes chemotherapy drugs that don’t belong to any other group because they’re unique. Some of them are:
- Asparaginase and pegaspargase
In addition to chemotherapy, there are many other types of chemical therapies for cancer, such as targeted therapies, immunotherapy, or hormone therapy. All these therapeutic agents have allowed great strides in the treatment of cancer.
However, we still have a very big challenge ahead and further research is needed in this therapeutic area. The ultimate goal, therefore, is to achieve highly specific types of chemotherapy that mostly attack only tumor cells.