Chemotherapy Explained
Chemotherapy is a form of cancer therapy which uses drugs to treat cancer. These specially designed drugs are commonly called cytotoxic (‘cyto’ meaning cell and ‘toxic’ meaning to ‘injure’ or ‘kill’). Many of these drugs are obtained from natural sources, such as plants. Other cytotoxic drugs are man-made. There are over sixty different drugs used in chemotherapy and many of these are used in different strengths and combinations.
Combination chemotherapy has been found to be more effective than treatment with a single drug. Doctors combine drugs with different mechanisms of action, different metabolic pathways, different times of onset of action and recovery, different side effects and onset of side effects. The cytotoxic drugs are inserted into the body by a number of different methods, and work at destroying cancer cells, as well as normal healthy cells.
How Chemotherapy Works
Chemotherapy drugs enter the bloodstream and travel throughout the body to most tissues. The drugs kill certain cells but mostly cells that are rapidly dividing i.e. cancer cells. This means that the drugs affect both cancer cells and normal cells (this is the reason hair loss often occurs).
Generally the effect on normal body tissues is temporary and they recover quickly from the drugs because of the body’s normal process of repair and healing. Cancer cells recover slowly and with more difficulty than normal cells. By the time the person is ready for the next chemotherapy treatment, the body’s normal cells have mostly recovered, yet the cancer cells have not. They are then killed with further treatment. If the chemotherapy treatment can kill all of the cancer cells, the cancer is curable. However, this is not always the case.
Chemotherapy as a form of cancer therapy does not work on all types of cancer. At first, the use of chemotherapy drugs may cause an initial disappearance of weaker cancer cells killed directly by the cytotoxic poisons and by the body’s own immune system. Hence, the tumour may seem as if it is regressing. When this happens, you may feel a little better for the next few weeks.
If the chemotherapy is continued during this period, the immune system becomes weakened even further. There may be a fall in white blood cells. In many cases, the tumour may become resistant to the chemotherapy drugs and it may begin to grow again. If this occurs, the oncologist generally changes the type of cytotoxic agent being used. However, the second course of drugs is usually less effective than the first.
Finally, the body’s immune system is so weakened, that it becomes susceptible to infections or even secondary tumours. Energy levels fall, symptoms increase and the doctor often recommends a small break from treatment to allow the body’s white blood cells to re-grow. However, this can be dangerous as it can cause the stronger cancer cells to increase.
Alternatively, they may recommend injections of a hormone to push white blood cells out of the bone marrow. Either way, the body is in a dangerous position. The body’s immune system is extremely weak and may be unable to fight off the onslaught of cancerous cells.
Therefore, chemotherapy as a traditional and conventional form of cancer treatment is only effective on particular types of cancer.
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