Radiation therapy is usually used for treatment of certain types of cancer. It can be given to shrink a tumor before surgery, or after surgery to destroy any cancer cells that may be left behind in the area. It may be given in conjunction with chemotherapy. Cancer cells divide more rapidly then normal cells and when radiation therapy is given to a patient, the cancer cells are more vulnerable to the effects of radiation and their DNA is unable to be replicated, thus stopping or slowing the cancer cells from spreading. Normal cells are less vulnerable to the effects of radiation, although they too can become harmed. However, they replicate at a much slower pace and DNA repair mechanisms can often times repair any damage to nearby healthy tissue. However, this is a risk for pregnant women as radiation can damage the cells of a fetus. Also, there are side effects including fatigue, nausea, burning of the skin and vomiting.