People treated for cancer during childhood have a risk of developing a second cancer. A second cancer can develop months or years after treatment for the first cancer is completed.
The benefit of treating a child’s cancer usually far outweighs the risk of developing a second cancer from treatment. The risk of developing a second cancer is different for each child, depending on the type of cancer, treatments received and lifestyle choices.
Who is at risk?
The risk of a second cancer is not the same for all childhood cancer survivors. Many different factors affect risk, including the following.
General risk factors
The following factors can affect a person’s risk of developing a second cancer after childhood cancer:
- sex (girls and women have greater risk for a second cancer)
- age (children who are younger when they are diagnosed and treated for the first cancer)
- type of first cancer
- type of treatments received
- certain genetic syndromes, including neurofibromatosis, Li-Fraumeni syndrome, familial polyposis or the genetic form of retinoblastoma
Type of cancer
People who had the following types of cancer during childhood have a greater risk of developing a second cancer:
- Hodgkin lymphoma and non-Hodgkin lymphoma
- hereditary retinoblastoma
- soft tissue sarcoma
- Wilms tumour
- bone cancer (osteosarcoma or Ewing sarcoma)
- brain or spinal cord tumour
The following treatments can also increase the risk of developing a second cancer:
- chemotherapy drugs, especially alkylating drugs
- radiation therapy
The risk for a second cancer is greater in the areas that were treated with radiation. The risk is also greater if radiation is given to the head or as total body irradiation (TBI) given before stem cell transplant. Radiation therapy and chemotherapy given together can also increase the risk of developing a second cancer.
Radiation therapy and chemotherapy can have cancer-causing, or carcinogenic, effects. With either type of therapy, the risk of a second cancer is related to the total dose received. The risk is even greater if radiation therapy and chemotherapy are given as combination therapy.
Children at high risk of developing a second cancer include those who received chemotherapy with:
- alkylating drugs, including cyclophosphamide (Cytoxan, Procytox), ifosfamide (Ifex) and mechlorethamine (nitrogen mustard, Mustargen)
- anthracycline drugs, including doxorubicin (Adriamycin) , daunorubicin (Cerubidine, Daunomycin)
- other drugs, including topoisomerase II inhibitors such as etoposide (Vepesid, VP-16) or teniposide (Vumon, VM-26)
The risk of developing a second cancer after radiation therapy is greater when:
- high doses of radiation therapy are given to a large area of the body
- radiation is given at a young age
If the second cancer is leukemia, it usually develops within 10 years of treatment for the original cancer. If a second cancer occurs after radiation therapy, it usually develops 10 or more years after treatment for the original cancer.
Types of second cancers
The most common types of second cancers that occur after treatments for childhood cancer include the following:
- Acute myelogenous leukemia (AML) can develop after treatment with chemotherapy.
- Breast cancer and lung cancer can develop after radiation to the chest.
- Thyroid cancer can develop after radiation to the neck, radioactive iodine or total body irradiation (TBI).
- Brain tumours can develop after radiation to the head.
- Bone or soft tissue sarcoma can develop in the area where radiation therapy was given.
- Stomach, liver or colorectal cancer can develop after radiation therapy to the abdomen.
- Non-melanoma skin cancer (which happens more often than melanoma skin cancer) can develop after radiation therapy.
- Melanoma skin cancer can develop after radiation therapy.
- Chronic myelogenous leukemia (CML) can develop after radiation therapy.
- Oral cavity cancer can develop after chemotherapy or when there is a history of chronic graft-versus-host disease (GVHD) following a stem cell transplant.
Some signs and symptoms that may suggest a second cancer include:
- easy bruising or bleeding
- excessive tiredness
- bone pain
- change in moles
- sores that don’t heal
- trouble swallowing
- painful bowel movements
- blood in the stool
- painful urination
- blood in the urine
- shortness of breath
- blood in the sputum
- discoloured areas or sores in the mouth that don’t heal
- constant or recurring headaches
- change in vision
- early morning vomiting on a regular basis
If you were treated for childhood cancer, you should tell your doctor about any new symptoms or symptoms that don’t go away.
Lowering the risk
People who are treated for cancer during childhood can help lower their risk for a second cancer by:
- not smoking and avoiding tobacco use
- eating a well-balanced diet
- maintaining a healthy body weight
- exercising regularly
- protecting yourself from sun damage
All people who are treated for cancer during childhood need regular follow-up. It is important to keep permanent, detailed records of the cancer treatments that you received during childhood. Sharing this information with your doctors can help them make better screening choices.
Follow-up may include monitoring or screening tests to check for second cancers. If you were treated for childhood cancer, you should have a physical exam each year.
The tests done during follow-up depend on the cancer treatments you had in the past and may include:
- complete blood count (CBC), which is usually done each year for 10 years for people treated for childhood leukemia
- skin exam to check for signs of skin cancer such as bumps or spots that look abnormal in size, shape, colour or texture, especially in the area where radiation therapy was given
- starting at puberty, clinical breast exam by the doctor or other healthcare professional to feel for lumps or anything that feels unusual for women who have had radiation therapy to the chest
- mammogram for women who had radiation therapy to the chest and do not have dense breasts, usually starting 8 years after treatment or at age 25, whichever is later
- MRI for women who had radiation therapy to the chest and have dense breasts, usually starting 8 years after treatment or at age 25, whichever is later
- colonoscopy to look inside the rectum and colon for polyps, areas that look abnormal and cancer for people who had radiation to the abdomen, pelvis or spine, usually starting 10 years after treatment or at age 35, whichever is later