Late side effects of radiation therapy are rare but they do occur and can begin as early as six months after the last treatment, according to the National Cancer Institute. The type of late side effects depends on what part of the body was treated, the length and strength of the therapy, and whether a patient also had chemotherapy. Radiation therapy patients should be monitored regularly for late side effects.
Brain Effects
Radiation therapy aimed at the brain can cause memory loss, cognitive problems, incontinence, movement problems and personality changes, according to NCI. Sometimes dead tumor cells can also form a mass in the brain. These difficulties can last months or even years but sometimes they can be treated with therapy, medicine or surgery.
Joint Problems
Radiation can cause scar tissue to build up in the area that was treated as well as weakness, according to the NCI. This can eventually lead to loss of movement in joints such as the shoulders or hips that can begin years after treatment is over. Physical therapy can often help restore movement and decrease pain.
Lymphedema
Lymphedema is swelling caused by a buildup of lymph fluid in an arm or leg that can be caused by radiation damage to lymph nodes, according to the NCI. This swelling can cause pain, heaviness and weakness in the affected limb. Lymphedema can be treated with physical therapy, medicine and compression garments. Exercise can not only treat the problem but prevent it.
Mouth Problems
Radiation therapy aimed at the head and neck can later cause dry mouth, cavities, and bone loss in the jaw, according to the NCI. Regular dental checkups can spot such problems so they can be treated. Regular dental hygiene including, flossing, brushing and daily fluoride treatments can also help prevent problems. Exercising the jaw can also help.
Cancer
Radiation therapy increases the risk of a new cancer developing years after treatment, though this is rare, according to the NCI. The risk of leukemia peaks between five and nine years after treatment and then gradually declines, according to the American Cancer Society. Other cancers take longer to develop and may not show up before more than a decade has passed after treatment. For this reason, regular checkups to check for both recurrence of the original cancer and any new cancers will be needed for the rest of the patient's life.
Other Risks
Radiation therapy to the pelvis can cause infertility and urinary or bowel problems, according to the American Cancer Society. Radiation in the chest can cause scarring in the lungs and heart that can limit a person's ability to function.
