Ask the Doctor
September 17, 2013

Difference between chemotherapy and radiotherapy

Dear Doc,

What is chemotherapy? What is radiotherapy?


Dear Brianna,

Chemotherapy refers to using medicines that stop the growth of cancer cells or organisms. Chemotherapy can be given chiefly by administering it through the veins or as oral medications.{{more}}

The perfect form of chemotherapy will only destroy the intended target cells and not trouble the normal cells of the body. This is wishful thinking, as we are yet to have such an ideal drug. You might hear the term cell-marker or cancer-marker used when someone has a diagnosis. What researchers are interested in, is something on the cancer cells that a drug will attack and thus protect the other normal cells. One of the drawbacks of the use of chemotherapy is that its action is widespread, thus destroying normal cells in the process. When most people talk about chemotherapy (CHEMO for short) they are referring the use of anti-neoplastic (anti-cancer) drugs to treat persons who have been diagnosed with cancer.

Radiotherapy is the use of radiation to kill and prevent the expansion of cells. Radiation is referred to the energy that is given off by some materials, like uranium, that can disrupt the mechanism of the cells so that they cannot reproduce or repair themselves. The concept is that the cells which have the most activity will be affected the most. Since cancer cells are generally multiplying faster than non-cancerous cells, they are affected much more.

Both chemotherapy and radiotherapy are used to treat cancers of different nature and stages of growth. They can be used in combination or alone. Location of a cancer is of significant importance when using radiotherapy, as delivery of the radiation must be as precise as possible on the cancer, so that neighbouring healthy tissues and organs are not damaged.


SVG Cancer Society,

P.O. Box 709, Kingstown.