What is chemotherapy?
Chemotherapy is now solely to the treatment of cancer with drugs, while originally the name for all types of treatments with chemicals (medication). In addition to surgery and radiotherapy, chemotherapy is one of the three pillars for the treatment of patients with cancer. A series of treatments is also known as chemotherapy to each other, is also called a cytostatic compound used for this purpose.
Principles of application
Chemotherapy is intended to kill the cancer cells. The ideal chemotherapy kills all tumor cells without affecting healthy cells. In a very few exceptions for very specific tumors after these resources have not yet been found. Side effects that faces almost every patient receives, fatigue and hair loss.
Because cancer cells divide rapidly, the therapy focused on rapidly dividing cells. This reduces the number of blood cells after treatment, the hair falls out, it may cause nausea. Because healthy bone marrow cells, hair follicles, cells of the gastric mucosa, and the like to recover more quickly than cancer cells, it gives, as soon as the healthy tissue is restored, a new course. By repeating this several times, the tumor grows slowly or he is getting smaller.
Adjuvant treatment
Research suggests that the outlook for people with certain types of cancer are better, when the surgery is combined with chemotherapy, before, after, or both before and after surgery. For example, in breast cancer surgery less invasive than before, but this surgery is more often than in the past combined with radiation and chemotherapy.
Combination
Cancer cells develop resistance to chemotherapy. Therefore one starts in mid-fifties with combining different types of chemotherapy during the same treatment. By bombing cancer cells with drugs that work in their own way, you're more likely that they all have to be one of them sensitive. By providing a combination of means, one can save the tumor harder and take the healthy tissue. It then combines, for example, an agent which could possibly cause damage to the nervous system in a low dose with an agent that is detrimental to the bone marrow. Drugs used in chemotherapy can be divided into classical cytostatics and other resources.
Classical cytostatics
A cytostatic agent (plural cytostatics) is a drug used in the treatment of cancer. A cytostatic agent is intended to halt the division of cells (Cytos = cell; stasis = stop). The operation is based generally on the intervention in the chemical reactions in the cell that are needed for cell division (mitosis). These are especially rapidly growing cells damaged. Since the tumor cells are characterized by accelerated cell division, often in combination with a damaged cell repair mechanism, they are a lot more sensitive to the cytotoxic drugs than healthy cells. This distinction makes treatment with this in fact highly toxic substances as possible.
Hstory
During World War II bomb the Germans December 3, 1943 the port of the Italian city of Bari, where an American vessel damage that combat gas nitrogen mustard on board. It is the American doctor Cornelius Packard Rhoads, that the patients infected white blood cell count has fallen dramatically, while the rest of their tissue seems unaffected. Rhoads consider that mustard gas can be used for the treatment of lymphoma and leukemia. In America set pharmacologists Louis Goodman and Alfred Gilman around the same time that mustard gas quickly affects dividing cells.
in 1946 developed the first chemotherapeutic of mustard gas. Then it goes in search of similar materials. That family of alkylating chemotherapeutic agents is still used. In the fifties, there is targeted search for anti-metabolites, substances which prevent the formation of DNA, for example, by disruption of the function of folic acid. The discovery of cisplatin in 1965 in an experiment on the influence of electricity on the other hand, the cell division was again coincidence.
Resources
The following classical cytostatics are distinct
- alkylating agents, such as cyclophosphamide, by attaching an alkyl group to the DNA, it can not be copied.
- agents which interfere with the DNA-formation, so that cells can not divide, such as methotrexate and 5-fluorouracil, that are inhibitors of enzymes which are involved in the formation of DNA.
- means to prevent cell division, such as vinca alkaloids, and taxanes; vincristine example, the formation of the coil prevents that separate the chromosomes apart during cell division;
- anti-tumor antibiotics such as doxorubicin. Antibiotics are substances produced by a bacterium or fungus to inhibit competing fungi or bacteria or to kill. In addition to antibiotics which inhibit bacteria or fungi, there are also antibiotics that kill tumor cells.
- topoisomerase inhibitors such as irinotecan; topo-isomerase is an enzyme that reduces the tension in a newly formed DNA-spiral and thus prevents fractures. By inhibiting this, the DNA may no longer be read.
- other cytotoxic agents such as cisplatin. Cisplatin lay crosswise compounds in the DNA which copying is no longer possible.
Chemotherapy side effects
Cytostatic drugs inhibit not only cancer cells, but also healthy rapidly dividing cells, causing side effects occur, such as
- inhibition of the bone marrow, resulting in anemia, infections, and an increased risk of bleeding
- inhibition of cell division in the mucosa of the gastrointestinal tract, resulting in inflammation of the oral mucosa, nausea, vomiting, diarrhea
- hair loss and damaged nails. Cooling of the hands and feet can prevent the nails effects. Cooling of the skin can counteract baldness.
Further side effects
- Side effects, specifically for an agent, for example, damage to the nervous system (vincristine); the kidneys (eg cisplatin); heart (doxorubicin); the lungs (bleomycin), the liver etc.
- Agents can damage if used during pregnancy, the child seriously.
- If the patient heals of the cancer, can take years later a "second malignancy" can occur. This second malignancies are partly the result of treatment by the DNA damage caused.
- Nausea in chemotherapy can be controlled with 5HT3 blocking agents, such as granisetron, ondansetron and tropisetron. Cytostatics make namely 5HT3 released from certain cells and these agents block its effect. Adding a corticosteroid enhances the effect.
- Fatigue can be a big problem.
- Reduced fertility can also be a side effect of chemotherapy.
Precautions
Cytostatics are risky means. There is therefore need close monitoring at all possible side effects. The white blood cells and platelets will often need to be counted before being able to safely given a new course. A good running infusion is important but the main reason is that it is certain that the chemotherapy is effective in the vein, and not outside, as this may result in necrosis. Anyone who works with cytostatics, should also protect themselves from direct contact with the agent.
Other resources
- hormones and anti-hormones (such as tamoxifen in breast cancer)
- immunomodulators: agents that enhance the auto-immune response against the tumor (such as α-interferon or interleukin-2);
- monoclonal antibodies: antibodies specifically manufactured, for example, against proteins that are over-expressed on the cell membrane of a tumor;
- protein kinase inhibitors: small proteins that major pathways block (for example, cell proliferation or angiogenesis) in cancer;
- Other resources: eg bisphosphonates to inhibit the effects of botuitzaaiingen.
Indications
Chemotherapy is the main treatment for various forms of cancer, such as testicular cancer, Hodgkin's disease, non-Hodgkin's lymphoma and leukemia. When testicular cancer (even if it has spread) and Hodgkin's disease, a large percentage of patients are cured by chemotherapy.
For other cancers, such as breast cancer, chemotherapy is given when indicated as adjunctive therapy. This means that surgery is the primary treatment, and through additional chemotherapy, the risk of disease recurrence (relapse), or reduced occurrence of metastases (metastases).
Finally, there are cancers in which no cure is possible. Often it to cancer with metastases arose. The aim is than control or prevention of symptoms caused by the tumor, and prolongation of life. We call this palliative.
Also, antineoplastic drugs administered in cases of serious, non-malignant diseases, for example in some autoimmune diseases.
Localized
Chemotherapy works not only where it was needed. With selective perfusion one tries to separate the circulatory system of the liver, for example, from that of the rest of the body, so that one can treat a liver tumor elsewhere without causing any damage. It also tries to find delivery forms which ensure that the drug is activated only in the tumor.