Chemotherapy is often used to treat various types of cancer. These drugs, also called anti-cancer drugs, destroy cancer cells by preventing them from growing and multiplying. However, healthy cells are also harmed during the process, which is responsible for the side effects of treatment. Once chemotherapy is discontinued, healthy cells usually repair themselves and side effects gradually subside.
Common side effects include nausea, vomiting, fatigue, hair loss, anemia, confusion, depression, problems with blood clotting, stomatitis (sores in the mouth), mucosititis (sores in the throat), dry mouth, diarrhea, constipation, loss of appetite, peripheral neuropathy (burning, weakness, tingling or numbness in the hands and/or feet), acne, dry skin, rash, yellow and brittle nails, flu-like symptoms, fluid retention, decreased sperm motility and reduced sexual hormone production in women. Some chemotherapy drugs may also damage the kidneys and/or bladder. Chemotherapy also destroys healthy immune cells. Therefore, patients undergoing chemotherapy are immunocompromised and susceptible to infections.
Sometimes chemotherapy is the only treatment that a patient receives. However, chemotherapy is usually used in addition to other treatments, such as surgery or radiation therapy (treatment that uses high-energy rays to destroy cancer cells).
Chemotherapy is usually administered to help shrink a tumor before surgery or radiation therapy (neo-adjuvant therapy), to help destroy cancer cells that remain after surgery or radiation therapy (adjuvant chemotherapy) or to help destroy cancer if it recurs or has spread to other parts of the body.
Some chemotherapy drugs are used for many different types of cancer, while others are specialized to treat one or two types of cancer. A qualified healthcare provider will recommend a treatment plan based on the type of cancer, where the cancer is located, the effect of cancer on the patient's normal body functions and the patient's overall health.
Chemotherapy is usually administered intravenously (IV). During the procedure, a thin needle is inserted into a vein on the lower arm in order to administer the drug. The needle is removed at the end of the treatment session. Chemotherapy can also be delivered intravenously through catheters, ports or pumps. It can also be taken orally in a capsule or liquid form.
Some patients may experience allergic reactions to chemotherapy. Drug allergies are characterized by a hypersensitive reaction of the immune system to certain medications. Hypersensitivity reactions to chemotherapy, although rare, have been reported with most chemotherapy drugs. The reactions occur most frequently with L-asparaginase, paclitaxel, docetaxel, teniposide, procarbazine and cytarbine. There is a higher risk of allergic reaction if the drug is administered in large doses or if it is administered intravenously.
In some cases, the allergic reaction can be potentially life threatening. The most severe type of allergic reaction, known as anaphylaxis, may occur immediately after taking a drug. Symptoms of anaphylaxis can vary from mild to severe The most dangerous symptoms are low blood pressure, difficulty breathing, shock and loss of consciousness, all of which can be fatal. Anaphylaxis is an emergency condition that requires immediate medical attention. Epinephrine is a medication used to treat severe allergic reactions such as anaphylaxis. Administering the epinephrine as soon as possible improves the patient's chance of survival and a quick recovery.
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types of allergic reactions
Allergic reactions can be classified into four immunopathologic categories using various classification systems. The Gell and Coombs allergic classification system is based on the immune system's response to the allergen, not on the severity of the reaction. Allergic reactions to drugs, including chemotherapy, is classified as a Type I allergic reaction.
Type I: Type I allergic reactions involve immunoglobulin E (IgE), which is specific for a particular drug, antigen or other allergen that triggers the allergic reaction. The allergen binds to the immunoglobulin on specific immune cells called basophils and mast cells. This binding results in the release of chemicals that cause inflammation in the body (like histamine, serotonin, proteases, bradykinin generating factor, chemotactic factors from immune cells, leukotrienes, prostaglandins and thromboxanes) within 30 minutes of exposure. These chemical mediators cause allergy symptoms, such as urticaria (hives), runny nose, watery eyes, sneezing, wheezing and itching. This type of allergic reaction is often seen with penicillin, latex, blood products and vaccines, among other allergens.
Type II: This classification is called a cytotoxic reaction because it involves the destruction of the host cells. An antigen associated with a specific cell initiates cytolysis of the cell by an antigen-specific antibody, such as immunoglobulin G (IgG) or immunoglobulin M (IgM). This reaction often involves blood elements, such as red blood cells, white blood cells or platelets. It often occurs within five to twelve hours of exposure to the allergen, which may include penicillin, quinidine, phenylbutazone, thiouracils, sulfonamides or methyldopa.
Type III: This category involves the formation of an antigen-antibody immune complex, which deposits on blood vessel walls and activates cell components called complements. This causes a serum sickness-like syndrome, involving fever, swelling, skin rash and enlarged lymph nodes, in about three to eight hours. It may be caused by a variety of allergens, including penicillins, sulfonamides, intravenous (IV) contrast media and hydantoins.
Type IV: This classification involves delayed cell-mediated reactions. Antigens on the allergen release inflammatory mediators within 24 to 48 hours of exposure. This type of reaction is seen with graft rejection, latex contact dermatitis and tuberculin reaction.