Chemotherapy is a type of drug treatment used to treat cancer. It is used to treat solid tumours (cancerous lumps) affecting organs such as the breast or bowel, as well as blood cancer. Chemotherapy is used at various stages of cancer. Chemotherapy may be given at one or more of the following stages.
1. Before surgery (neo-adjuvant therapy) to shrink a tumor so that it is easier to remove from the body.
2. After surgery (adjuvant therapy) to make sure that any cancerous cells left in the body after removal of a tumor are killed.
3. In advanced stage to remove cancerous cells that have spread through the body, or to slow the progress of the disease.
Key words: Chemotherapy, Tumor, Cancer, Cancerous cells
All chemotherapy drugs work by attacking cells that are dividing rapidly. Normal cells divide at a rate that is tightly controlled by the body. However, in cancer cells, the cell division goes wrong, leading to uncontrolled production of new cells and the formation of a tumor or blood cancer. Chemotherapy drugs interfere with the division of these cells and may cause the cancer to die back completely
Drugs used for chemotherapy:
There are over 50 different chemotherapy drugs available. The drugs are used in different ways according to the type of cancer, how advanced it is and the general health of the person being treated. Different chemotherapy drugs may be used alone or in combinations of two or more drugs. Most chemotherapy drugs affect the DNA in cancer cells. The main groups of chemotherapy drugs are:
Alkylating drugs: stick to one of the DNA strands and prevents them dividing E.g.: cyclophosphamide
Cytotoxic antibiotics: stick to DNA causing it to become tangled and preventing the cell from dividing E.g.: doxorubicin
Antimetabolites: stop cells working by preventing them making and repairing DNA. E.g.: Methotrexate
Vinca alkaloids: disrupt the mechanism that enables one cell to split into two new cells. E.g.. vindesine
Other drugs include platinum compounds like carboplatin, and taxanes such as docetaxel. They have various modes of action.
Camptothecin: The Camptothecin are a new class of chemotherapeutic agents with a novel mechanism of action targeting the nuclear enzyme topoisomerase I. This compound was isolated from the bark of a Chinese tree. This drug and its derivatives are inhibitors of topoisomerase I. Camptothecin itself is poorly soluble and causes significant toxicity. Several more soluble and less toxic derivatives are now available Eg: irinotecan (CPT-11)
Other treatments used alongside chemotherapy, include drugs that alter hormone levels in the blood and slow down the growth rate of hormone-dependent tumours. They include: Angiogenesis inhibitors prevent the growth of blood vessels inside a tumor, starving it of blood. Biological therapies help the body’s immune system to attack cancer cells. Monoclonal antibodies – stick to cancer cells and stimulate the body to destroy them.
Administration of drugs: Most chemotherapy drugs are given directly into the bloodstream via infusions and injections. In some cases tablets, creams will be used based on stage of cancer and type of cancer
Duration of treatment: Chemotherapy is given in cycles of treatment alternating with rest periods to allow the body to recover from side-effects. The length of chemotherapy treatment depends on the type of cancer, how much it has spread through the body, and the types of drugs used, the severity of side-effects and how successful the treatment is.
Side-effects: Chemotherapy does not only target cancer cells, but any cells that divide rapidly which include bone marrow cells and skin, hair-producing cells, and the cells that line the mouth and digestive system. Damage to these healthy cells may produce various side effects, including Tiredness, nausea, vomiting, Diarrhea or constipation, Hair loss, Sore mouth, Mouth ulcers and changes in the sense of taste, early menopause in women etc.,
Many of these side-effects can be controlled using additional drugs. Furthermore, most side-effects are temporary and will pass once treatment is completed.
Having a healthy, balanced diet and being proactive one can escape from this dangerous cancer. Chemotherapy gives a hope for cancer patients but sometimes the cure can be worse than the disease. Anyhow it’s “Better to light one small candle than to curse the darkness”.
A REVIEW ON CHEMOTHERAPY