Surgery and radiotherapy are localized treatments, removing or destroying cancer cells at a specific site in the body. Chemotherapy on the other hand is the use of special drugs to kill cancer cells. The drugs are usually carried in the bloodstream throughout the body to reach cancer cells wherever they occur.
There are many different anti-cancer drugs in use but they all work by interfering with the ability of cancer cells to divide and reproduce themselves. The affected cells become damaged and eventually die. Because of this the drugs are called 'cytotoxics' which literally means cell poisons.
The drugs are most commonly given by mouth or injection and are absorbed into the blood, to travel around the body and reach all the cancer cells, wherever they are located. A combination of different drugs may be used to maximise the destruction of cancer cells.
Chemotherapy treatments are usually given in time limited courses with rest periods in between to allow your body to recover. For example, some drugs are given at two, three or even six week intervals. This is necessary because the chemotherapy drugs damage all cells that are multiplying rapidly, which includes some normal cells such as hair roots, bone marrow and the lining of the intestine. Unlike cancer cells, normal cells are able to repair themselves so that any damage is usually temporary. Cancer cells recover with more difficulty and repeated treatments will result in more cancer tissue being killed.
If chemotherapy can eventually kill all the cancer cells, the cancer is in remission and potentially curable. The cure rates vary from the majority in some cancers to the minority in others, depending on the type of cancer. In many cancers, cure is unlikely and then chemotherapy may be given to shrink the cancer, prolong life and relieve symptoms. |
