Radiation therapy is another conventional treatment method used to treat cancer.  The mechanism of action is that it damages DNA.  The damage is done directly by atomic particles (i.e., protons, electrons, neutrons or ions) that are shot at the tumor and end up directly damaging the DNA chain of the cells; or indirectly by creating extremely reactive free radicals in the water which then damage the DNA.  It is theorized that because cancer cells have less DNA-repairing capability, they would be more susceptible to radiation exposure than normal cells.

Radiation therapy is usually used when the tumor is localized.  If the cancer has metastasized, it is usually untreatable with radiation, since radiation therapy cannot be used to treat the entire body.  In some situations, part of the tumor is surgically removed, and the rest is treated with radiation therapy.

Radiation therapy is painless when being applied.  Low-dose treatments that are palliative may give minimal side effects, but may sometimes cause short-term pain.  The duration, intensity and type of side effect is dependent on the type of cancer, the location of the tumor, the length and amount of radiation exposure and the individual characteristics of the patient.

Acute (short-term) side effects

Radiation exposure may damage the skin of the patient.  It can cause damage where ever it is administered.  The level of damage and recovery will depend on the cell turnover rate of the particular epithelial cells at the point of contact. Recovery from this damage is usually rapid.  Skin damage seems to be the worst at places where the body has natural folds such as underneath the female breast, behind the ear or the groin.  If the bowel or lower GI tract are treated, soreness, diarrhea or nausea may result.  If the head or neck are treated, temporary soreness or ulcers may be experienced in the mouth or throat.  Swallowing may be painful, and painkillers may have to be prescribed for relief.  The esophagus may also be negatively affected if it is exposed to the radiation.

Swelling may also be caused by radiation therapy.  It is also known as edema.  This can cause problems in treatment as well.

Infertility may result, as the gonads are very sensitive to radiation exposure.

Nausea and/or vomiting can result.

Low blood counts-can have reduced red and/or white blood cell levels.

Medium and Long Term Side Effects

  • Hair loss- is usually limited to the point of exposure, but tends to be permanent,
  • Dryness-dry mouth or dry eyes may result if they are exposed to the radiation,
  • Fibrosis-the exposed portions of the body usually lose their elasticity when exposed to radiation due to scarring,
  • Fatigue-may last anywhere from a few months to a few years.  Patients may experienced decreased energy levels, lethargy, and reduced activity levels,
  • Cancer-radiation is a potential cause of cancer,
  • Death-radiation can cause death from heart disease with certain radiation therapy regimens.