Chemo, or chemotherapy, involves the use of drugs to destroy cancer cells or stop them from multiplying, while radiation therapy is the use of high-powered radiation to destroy cancer cells. Cancer cells are more susceptible to both chemotherapy and radiation therapy, but normal brain cells and other cells in the body can also be affected by these treatments. The side effects of these treatments depend on the dose, length of treatment and type of drug or radiation used. Different systems in the body are affected.
Central Nervous System
Normal brain tissue can be damaged by radiation therapy, with some loss of brain function if large areas of the brain are exposed to radiation, according to the American Cancer Society. Memory loss, personality changes and loss of concentration are some of the problems that can arise from radiation therapy. Headaches and irritability are also possible side effects of brain radiation. Radiation necrosis, a large mass of dead tissue at the site of the radiation that may require surgical removal, is also described by the American Cancer Society. According to the American Society of Clinical Oncology, a slow decline in intellectual performance is also possible, though the side effects are much less with improved technology. Cisplatin and carboplatin, used in chemotherapy, can cause hearing loss in susceptible patients with brain tumors, says the American Cancer Society.
Digestive System
Nausea and vomiting are common side effects of both radiation therapy and chemotherapy, mentioned in treatment of brain tumor by the American Cancer Society. Mouth sores, loss of appetite and diarrhea are possible side effects with chemotherapy in brain tumors.
Hematological System
The bone marrow, with its rapidly dividing cells, is easily affected by chemotherapy. Bone marrow suppression leads to low blood cell counts. Anemia, with weakness and fatigue; low white cell counts, with reduced body resistance to infections; and low platelet count, with easy bruising and bleeding are all mentioned by the American Cancer Society as side effects of chemotherapy in patients with brain tumor.
Other Side Effects
Skin changes like hair loss and discoloration are seen with both radiation therapy and chemotherapy. Local reactions at the site of radiation therapy may include thinning of the skin, dryness and blistering. Kidney damage is seen with some particular drugs used in chemotherapy of brain tumors, such as cisplatin and carboplatin. Radiation therapy causes damage to genetic material, which, according to the American Cancer Society, can result in a second cancer arising in tissues over the area of the brain tumor like the skull bones or the meninges, the covering of the brain. Thus, a bone cancer or a meningioma can arise in an area previously exposed to radiation therapy for a brain tumor.
