Chemotherapy refers to use of antineoplastic drugs to treat cancer in popular usage and also use of a combination of drugs into a cytotoxic homogeneous treatment option. The term refers to antibacterial chemotherapy or antibiotics in non-oncological use. In 1909 a compound that is arseniccalled arsphenamine was the first modern chemotherapeutic agent, discovered by Paul Ehrlich. It was used in the treatment of syphilis. Penicillin discovered by Alexander Fleming and sulfonamides discovered by Domagk later followed this discovery.
Cancer cells divide rapidly which is one of the main properties of most cancer cells, and most commonly chemotherapy acts by killing these cancer cells. Chemotherapy also harms cells that rapidly divide in normal circumstances, for example cells in the hair follicles, digestive tract, and cells in the marrow of the bones . All this results in the alopecia or hair loss, mucositis or inflammation of the lining of the digestive tract and myelosuppression or the decreased production of blood cells, which are the most common chemotherapy side effects.
Cytostatic chemotherapy agents are used in the treatment of autoimmune diseases. These are suppressants for transplant rejections, rheumatoid arthritis, Lupus, Polymyositis, Dermatomyositis, and multi sclerosis. There are also some new anticancer drugs which act directly against the abnormal proteins in cancer cells, through a process termed as targeted therapy.
Adverse effects of chemotherapy:
Depending on the type of medications used, chemotherapeutic techniques have a range of side effects. Fast dividing cells of the body are mainly affected by the most common medications. Even the cells lining the intestines, stomach, and mouth as well as the blood cells are affected. There are a number of side effects of chemotherapy.
A cancer patient might already be tired from cancer related fatigue and the treatment too can be physically exhausting for the patient. Mild to severe anemia may be produced. To mitigate anemia, treatments include intake of iron supplements, blood transfusions and erythropoietin hormones to boost production of blood.
Chemotherapy side effects also involve reducing the number of platelets in the blood, which is likely to also reduce with medications that rapidly kill blood cells or dividing cells. This can result in bleeding and bruises. Through platelet transfusions, very low platelet count may be boosted. To allow platelet counts to recover, sometimes chemotherapy treatments are postponed.
Potentially fatal infections are a result of depression of the immune system. Most of the infections are due to naturally occurring microorganisms present in the skin and gut of the patient, although patients are encouraged to avoid sick people, wash their hands and take other infection reducing steps. Systemic infections manifest such as shingles, localized outbreaks and sepsis. Sometimes because the immune system is suppressed to critically low levels, chemotherapy treatments are postponed.
Dramatic hair loss is caused by some medications that kill rapidly dividing cells whereas other medications cause the hair to thin out. After the last treatment the hair starts growing back after a few weeks because the medications have temporary effect. Sometimes the hair tends to curl and such a condition is called the ‘chemo perm’ At times with resultant symptoms damage to specific organs may occur. Liver damage or hepatotoxity, damage to the inner ear or Ototoxicity which produces vertigo, heart damage or cardiotoxicity , and kidney damage or nephrotoxicity are some developments.
Chemotherapeutic medications that kill fast dividing cells have common chemotherapy side effects like vomiting, nausea and can also manifest with the onslaught of constipation or diarrhea. Because of gastrointestinal damage or when the patient keeps vomiting frequently, dehydration and malnutrition can result when the patient does not drink or eat enough. Also in an effort to allay heartburn or nausea if the patient eats too much, this can result in occasional weight gain or even rapid weight loss. Some steroid medications also cause weight gain. With antiemetic drugs, these chemotherapy side effects can frequently be eliminated or eliminated. Self care measures are recommended, such as drinking clear liquids or ginger tea and eating frequent small meals. This temporary effect resolves frequently withn a week after completing the treatment.
Myelosuppression and immunosuppression:
Chemotherapy side effects also involve depression of the immune system which is caused by virtually all chemotherapeutic regimens. This results in decrease in platelets, red blood cells, white blood cells and often paralysis of the bone marrow. When the platelets and red blood cells decrease the counts are better with blood transfusion. In severe myelosuppression all the bone marrow stem cells get destroyed. It becomes necessary to resort to autologous or allogenic bone marrow transplants. In the case of Inallogenic bone marrow transplant, the source is the donor, and in autologous bone marrow transplant, before the treatment the cells removed from the patient and then re-injected later. Because of this interference with bone marrow, some patients develop many other diseases. In the recent times, the use of emetogenic chemotherapy and better antiemetics has reduced.