Second cancers

Although the risk is low, cancer survivors have a slightly higher chance of developing a second cancer compared to people of the same age who haven't had cancer. Sometimes second cancers happen as a late effect of treatment for cancer during childhood. If secondary leukemias occur, they usually happen within the first 10 years after treatment. Secondary solid tumours most commonly appear 10 or more years after treatment.

The benefit of treating a cancer usually far outweighs the risk of developing a second cancer from treatment. The risk of developing a second cancer is different for everyone, depending on the type of cancer, treatments received and lifestyle choices.

Radiation therapy and chemotherapy can have cancer-causing (carcinogenic) effects. With either type of therapy, the risk of a second cancer is related to the total dose received. The risk is higher if radiation therapy and chemotherapy are given as combination therapy. The type of original cancer you had, as well as other factors, can also affect your risk for a second cancer.

Radiation therapy increases the risk of developing a secondary leukemia or solid tumour. The risk for a second cancer is greater in the areas that were treated with radiation.

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, such as total body irradiation (TBI) given before a stem cell transplant
• radiation is given at a young age

Chemotherapy may be used for treatment or as part of preparation for a stem cell transplant. The following chemotherapy drugs increase the risk of developing a secondary leukemia:

• alkylating drugs, including procarbazine (Matulane), chlorambucil (Leukeran), carmustine (BICNU), busulfan, melphalan, cyclophosphamide (Procytox) and ifosfamide (Ifex)
• anthracycline drugs, including doxorubicin and daunorubicin (Cerubidine)
• other drugs, including topoisomerase 2 inhibitors such as etoposide

People who had the following types of cancer have a greater risk of developing a second cancer:

• Hodgkin lymphoma and non-Hodgkin lymphoma
• hereditary retinoblastoma
• soft tissue sarcoma
• neuroblastoma
• leukemia
• Wilms tumour
• bone cancer (osteosarcoma or Ewing sarcoma)
• brain or spinal cord tumour

The following factors can increase the risk of second cancers:

• being a woman
• being a child when the original cancer was treated
• having a family history of cancer or certain genetic syndromes, including neurofibromatosis, Li-Fraumeni syndrome, familial polyposis or hereditary retinoblastoma

The most common types of second cancers that occur after treatments for cancer include the following:

• Leukemia, most commonly acute myelogenous leukemia (AML), can develop after radiation therapy or treatment with certain chemotherapy drugs or drug combinations. Having had both radiation therapy and chemotherapy to treat cancer increases the risk for leukemia more than having the either treatment alone.
• Breast cancer and lung cancer can develop after radiation to the chest.
• Thyroid cancer can develop after radiation to the neck, radioactive iodine or TBI.
• Brain tumours can develop after radiation to the head.
• Stomach, liver or colorectal cancer can develop after radiation therapy to the abdomen.
• Bone, soft tissue sarcoma, non-melanoma skin cancer or melanoma can develop in the area where radiation therapy was given.
• Oral cavity cancer can develop when cells in the mouth are damaged from 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
• paleness
• fatigue
• bone pain
• a change in moles
• sores that don't heal
• a lump or growth
• trouble swallowing
• changes in bowel or bladder habits
• unusual bleeding or discharge
• shortness of breath
• a nagging cough or hoarseness
• constant or recurring headaches
• a change in vision
• early morning vomiting on a regular basis

Tell your doctor about any new symptoms or symptoms that don't go away.

After cancer treatment, you can help lower your risk for a second cancer by:

• not smoking and avoiding tobacco
• eating a well-balanced diet
• maintaining a healthy body weight
• exercising regularly
• protecting yourself from sun damage

All people who are treated for cancer need regular follow-up. It is important to keep permanent, detailed records of the cancer treatments that you received. 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. 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:

• blood tests, such as a complete blood count (CBC)
• a pituitary screen
• a 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
• a clinical breast exam (once each year starting at puberty) by a doctor or other healthcare professional to feel for lumps or anything unusual if you had radiation therapy to the chest
• a mammogram (usually starting 8 years after treatment or at age 25, whichever is later) if you had radiation therapy to the chest and do not have dense breasts
• an MRI (usually starting 8 years after treatment or at age 25, whichever is later) if you had radiation therapy to the chest and have dense breasts
• a colonoscopy (usually starting 10 years after treatment or at age 35, whichever is later) to look inside the rectum and colon for polyps, abnormal areas and cancer if you had radiation to the abdomen, pelvis or spine