Late effects are treatment-related health problems that appear months or years after treatment has ended.

The treatment of cancer may damage healthy cells at the same time it destroys cancer cells. Some cancer treatments, such as chemotherapy, radiation therapy, and bone marrow or stem cell transplant, stop the growth of rapidly dividing cells, such as cancer cells. Since bones, tissues, and organs that are growing with the child have cells that are also dividing rapidly, cancer treatment can prevent them from developing normally. Other cancer treatments include surgery to remove all or part of certain organs that have cancer in them. The damage from these cancer treatments can be mild or serious, and the effects may be seen during treatment or months to years later.

Side effects that continue or appear after cancer treatment has ended are called late effects. It is important for the parents and the patient to know that children treated for cancer (childhood cancer survivors) may develop late effects from their treatment.

Late effects of cancer treatment may affect the following in childhood cancer survivors:

• Organs, bones, or body tissues.
• Mood, feelings, and actions.
• Thinking, learning, and memory.

The risk of developing late effects is related to the type of cancer or type of treatment.

The risk that a cancer treatment will cause late effects depends on many things, including the following:

• The type of cancer and where it is in the body.
• The child’s age (when treated).
• The type and amount of treatment.
• The area treated.
• Genetic factors or health problems the child had before the cancer.

Regular follow-up by health professionals who are expert in finding and treating late effects is important for the long-term health of childhood cancer survivors. Records about the cancer diagnosis and treatment, including all test results, should be kept by childhood cancer survivors (or their caregivers). This information may be used to help find and treat late effects.

Doctors are studying the late effects that cancer treatments cause in childhood cancer survivors. They are trying to find out if changing treatment can help prevent or lessen late effects in childhood cancer survivors.