The types of cancer that occur most often in children are different from those seen in adults. The most common cancers found in children are:
Leukaemias, which are cancers of the bone marrow and blood, are the most common childhood cancers. They account for about 31% of all cancers in children. The most common types in children are Acute Lymphocytic Leukaemia (ALL) and Acute Myelogenous Leukaemia (AML). Leukaemia may cause bone and joint pain, fatigue, weakness, pale skin, bleeding or bruising, fever, weight loss and other symptoms.
Brain and central nervous system tumours are the second most common cancers in children, making up about 21% of childhood cancers. There are many types of brain tumours and the treatment and outlook for each is different. Most brain tumours in children start in the lower parts of the brain, such as the cerebellum or brain stem. They can cause headaches, nausea, vomiting, blurred or double vision, dizziness and trouble walking or handling objects. Adults are more likely to develop tumours in upper parts of the brain. Spinal cord tumours are less common than brain tumours in both children and adults.
Neuroblastoma starts in early forms of nerve cells found in a developing embryo or foetus. About 7% of childhood cancers are neuroblastomas. This type of cancer occurs in infants and young children. It is rarely found in children older than 10. This tumour can start anywhere but is usually in the belly (abdomen) and is noticed as swelling. It can also cause bone pain and fever.
Wilms' Tumour starts in one, or rarely, both kidneys. It is most often found in children around 3 to 4 years old, and is uncommon in children older than the age of 6. It can show up as a swelling or lump in the belly (abdomen). Sometimes the child might have other symptoms, like fever, pain, nausea or poor appetite. Wilms' tumour accounts for about 5% of childhood cancers.
These cancers start in certain cells of the immune system called lymphocytes. They most often grow in lymph nodes and other lymph tissues, like the tonsils or thymus. They can also affect the bone marrow and other organs and can cause different symptoms depending on where the cancer is. Lymphomas can cause weight loss, fever, sweats, tiredness (fatigue) and lumps (swollen lymph nodes) under the skin in the neck, armpit, or groin. The 2 main types of lymphoma are: Hodgkin's lymphoma (sometimes called Hodgkin's disease) and non-Hodgkin's lymphoma. Both types occur in children and adults.
Rhabdomyosarcoma starts in cells that normally develop into skeletal muscles. (These are the muscles that we control to move parts of our body.) This type of cancer can start in the head and neck, groin, belly (abdomen), pelvis or in an arm or leg. It may cause pain, swelling (a lump) or both. This is the most common type of soft tissue sarcoma in children. It makes up about 3% of childhood cancers.
Retinoblastoma is a cancer of the eye. It accounts for about 3% of childhood cancers. It usually occurs in children around the age of 2 and is seldom found in children older than 6. Retinoblastomas are usually found because a parent or doctor notices a child's eye looks unusual. Normally when you shine a light in a child's eye, the pupil (the dark spot in the centre of the eye) looks red because of the blood in vessels in the back of the eye. In an eye with retinoblastoma, the pupil often looks white or pink. This white glare of the eye may be noticed after a flash picture is taken.
Primary bone cancers (cancers that start in the bones) occur most often in older children and teens but they can develop at any age. They account for about 4% of childhood cancers. Primary bone cancer is different from metastatic bone cancer, which is cancer that started somewhere else in the body and has spread to the bone. Metastatic bone cancer is more common than primary bone cancer because many types of cancer (including many cancers in adults) can spread to the bone. Two main types of primary bone cancers occur in children:
Cancer can be hard to detect in children. Children with cancer may experience the following symptoms or signs. Sometimes, children with cancer do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not cancer.
Some of the symptoms include:
Doctors and researchers don't know what causes most childhood cancers. A small percentage of cancers can be linked to the genetic disorder Down's syndrome, other inherited genetic abnormalities and previous radiation treatment. Environmental causes, such as exposure to infectious and toxic substances, are unlikely to cause childhood cancer.
Doctors use many tests to diagnose cancer and find out if it has spread to another part of the body (metastasis). Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy or surgery to remove as much of the tumour as possible is the only way to make a definitive diagnosis. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has spread.
In addition to a physical examination, the following tests may be used to diagnose childhood cancer:
A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but except for certain types of brain tumours, only a biopsy can make a definite diagnosis. The type of biopsy performed depends on the location of the cancer. The sample removed during the biopsy is analysed by a pathologist. A pathologist is a doctor who specialises in interpreting laboratory tests and evaluating cells, tissues and organs to diagnose disease.
These two procedures are similar and often done at the same time to examine the bone marrow. Bone marrow has both a solid and a liquid part. A bone marrow aspiration removes a sample of the fluid with a needle. A bone marrow biopsy is the removal of a small amount of solid tissue using a needle. The samples are then analysed by a pathologist. A common site for a bone marrow aspiration and biopsy is the pelvic bone, which is located in the lower back by the hip. The skin in that area is usually numbed with medication beforehand, and other types of anaesthesia may be used.
A CT scan creates a three-dimensional picture of the insides of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumours. A CT scan can also be used to measure the tumour size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient's vein or given as a pill to swallow.
RI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can also be used to measure the tumour size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient's vein or given as a pill to swallow.
A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient's body. This sugar substance is taken up by cells that use the most energy. Because cancerous cells tend to use energy actively, they absorb more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.
Surgery is the removal of the tumors, either cancerous or non-cancerous, and surrounding tissue during an operation. Many children with a tumour will need surgery at some point during their treatment. A surgical oncologist is a doctor who specialises in treating a tumour using surgery. The goal of surgery is to remove the entire tumour and the margin (tissue around the tumour), leaving a negative margin (no cancer in the healthy tissue). For most childhood tumours, there is a microscopic amount of tumour left after surgery. Doctors will recommend chemotherapy, radiation therapy or other treatments for the remaining tumour.
Chemotherapy is the use of drugs to destroy cancer cells, usually by stopping the cancer cell's ability to grow and divide. Chemotherapy is given by a paediatric oncologist, a doctor who specialises in treating children with cancer.
Systemic chemotherapy is delivered through the bloodstream to reach cancer cells throughout the body. Common ways to give chemotherapy include an intravenous (IV) tube placed into a vein, muscle, spinal fluid or under the skin using a needle, or in a pill or capsule that is swallowed (orally). A chemotherapy regimen (schedule) usually consists of a specific number of cycles given over a set period of time. A patient may receive one drug at a time or combinations of different drugs at the same time.
Immunotherapy, also called biologic therapy, is designed to boost the body’s natural defences to fight cancer. It uses materials made either by the body or in a laboratory to improve, target or restore immune system function. Examples of immunotherapy include cancer vaccines, monoclonal antibodies and interferons.
Radiation therapy is the use of high-energy x-rays or other particles such as photons to destroy cancer cells. A doctor who specialises in giving radiation therapy to treat cancer is called a radiation oncologist. The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body. When radiation treatment is given using implants, it is called internal radiation therapy or brachytherapy. A radiation therapy regimen usually consists of a specific number of treatments given over a set period of time.
Immunotherapy, also called biologic therapy, is designed to boost the body's natural defences to fight cancer. It uses materials made either by the body or in a laboratory to improve, target or restore immune system function. Examples of immunotherapy include cancer vaccines, monoclonal antibodies and interferons.
A stem cell transplant is a medical procedure in which bone marrow that contains cancer is replaced by highly specialised cells, called hematopoietic stem cells that develop into healthy bone marrow. Hematopoietic stem cells are blood-forming cells found both in the bloodstream and in the bone marrow. Today, this procedure is more commonly called a stem cell transplant, rather than bone marrow transplant, because it is the stem cells in the blood that are typically being transplanted, not the actual bone marrow tissue.