Impartial cancer information, with an emphasis on breast cancer and melanoma. No sponsors or advertisers. Updated weekly. Written by Professor Richard Kefford, medical oncologist.


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Chemotherapy: the What and How


	How does chemotherapy work? Chemotherapy is the name given to treatment of cancer with drugs that kill cancer cells. These drugs, of which there are over 100 different types, are sometimes called “cytotoxic” drugs. Most of them interfere in one way or another with the ability of DNA to replicate itself. DNA is the central home of information in the cell. This process of replication or reproduction, is essential for cancer to survive and grow. Normal cells grow and die in a controlled way. When cancer occurs, cells in the body that are not normal keep dividing and forming more cells without control. Chemotherapy drugs destroy cancer cells by interfering with DNA replication and thereby stopping them from growing or multiplying. When cells experience an overwhelming amount of DNA damage they trigger off a process of “self-suicide”, called “apoptosis”. Of course DNA replication it is also essential for many normal cells in the body, and this is why chemotherapy has side-effects, particularly on cells which divide at a high rate, like the cells which form the roots of the hair, the cells which make sperm in the testes and eggs in the ovary, and those which constitute the bone marrow and make the blood cells. However, we have learnt in recent years that one of the reasons for the selectivity of chemotherapy for cancer cells over normal cells is that normal cells are adept at repairing the damage caused by cytotoxic drugs, whilst cancer cells, fortunately, are not. So we often see normal cells pausing after being exposed to chemotherapy while DNA repair is carried out. Cancer cells, however, carry defects in genes that allow DNA repair to occur, and often simply undergo “apoptosis” Why is it given in “cycles”? Chemotherapy is usually given in cycles of treatment with rest period in between. This is to allow the normal cells to undergo essential repair. With successive cycles we achieve cumulative reduction in the cancer cells while normal cells reconstitute themselves. Many chemotherapy drugs are given on a third-weekly cycle because, by careful clinical trials, we have worked out that this is what is needed for normal cells like those in the bone marrow to recover. Some drugs are given orally for 7 or 14 days, followed by a one or two-week recovery period. It differs slightly for each drug. What is “combination chemotherapy”? Because some drugs work better together than alone, two or more drugs are often given at the same time. This is called combination chemotherapy. What is adjuvant chemotherapy? Adjuvant chemotherapy is chemotherapy given after the primary treatment (usually surgery) to increase the chances of a cure. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, or biological therapy. For further information on adjuvant chemotherapy CLICK HERE . \| What's New \| FAQ Page \| Living with chemotherapy \| Dietary Advice \| Exercise \| The Flu Vaccine \| Insomnia \| Marijuana \| Alternative Medicine \| Managing Menopause \| Advice to Carers \| Breast Cancer \| Pain \| Useful Tips \| Chemotherapy: The What and How \| MRI Screening \| \| Your Cancer Information \| \| Return Home \| New Patients \| Services and Clinics \| Useful Links \| Contact Us \| Download Page \| Cancer Information \|