What is Cancer?

Every cell in our body is tightly regulated with respect to its growth, interaction with other cells and even its life span. Cancer occurs when a type of cell has lost these normal control mechanism and grows in a way that the body cannot regulate.

All kinds of cancer, including childhood cancer, have a common disease process whereby the cells grow out of control, develop abnormal sizes and shapes, ignore their typical boundaries inside the body, destroy their neighbor cells, and can ultimately spread (or metastasize) to other organs and tissues. As cancer cells grow, they demand more and more of the body’s nutrition. Cancer takes a child’s strength, destroys organs and bones, and weakens a child’s defenses against other illnesses.

What are the common childhood cancer?

Childhood cancer is relatively rare. Among all age groups, the most common childhood cancers are leukemia, lymphom , and brain tumours. As children enter their teen years, there is an increase in the incidence of  osteosarcoma (bone cancer). The sites of cancer are different for each type, as are treatment and cure rates. Data from The Malaysian National Childhood Cancer survey shows that the commonest childhood tumours are leukaemias, tumours of the brain and spinal cord, lymphomas, neuroblastoma, gonadal and germ cell tumours, kidney tumours, soft tissue sarcomas and retinoblastoma.The crude incidence of pediatric malignancies in Malaysia is 77.4 per million children aged less than 15 years (Lin HP).

What are the risk factors?

1 in 600 children develop cancer before the age of 15 years. For most cancers the cause remains unknown. Typically, the factors that trigger cancer in children are usually not the same factors that may cause cancer in adults, such as smoking or exposure to environmental toxins.

Rarely, there may be an increased risk of childhood cancer in children who have a genetic condition, such as Down syndrome. Children who have had chemotherapy or radiation treatment for a prior cancer episode may have an increased risk of a second malignancy. In almost all cases, childhood cancers arise from non inherited mutations (or changes) in the genes of growing cells. Because these errors occur randomly and unpredictably, there is currently no effective way to prevent them.

Where should the child with cancer be treated?

Once cancer has been diagnosed, it is important for parents to seek help for their child at a medical center that specializes in pediatric oncology, or treatment for childhood cancer.

In Malaysia the main childhood cancer centres are Institut Pediatrik, Hospital Kuala Lumpur, University Malaya Medical Centre (UMMC), Hospital University Kebangsaan Malaysia (HUKM), Hospital Universiti Sains Malaysia, Kubang Kerian (HUSM), Hospital Umum Kucing, Sarawak, Hospital Pulau Pinang, Hospital Likas, Kota Kinabalu and Hospital Sultan Ismail, Johor Bharu.

Common medical procedures and tests

If your doctor suspects that your child may have cancer, he will refer your child to a paediatric oncologist who will take a thorough medical history of your child’s past and present illness and conduct a physical examination. Depending on the clinical findings, your child may have to undergo some procedures and tests such as:

• Blood test – A complete blood count or CBC. This measures the number of white blood cells, haemoglobin and platelets in a blood sample. A blood smear will be done on the same sample to look for the presence of “blasts” or abnormal white cells which could suggest the possibility of leukaemia.
• Bone marrow aspiration or bone marrow biopsy – This type of biopsy examines the bone marrow under a microscope to confirm the presence of leukemia. For other cancers, this test is performed as part of a staging procedure to see how far the cancer has spread.
• Lumbar puncture or spinal tap – This test obtains a sample of spinal fluid – the liquid that surrounds the brain and spinal cord. The doctor looks at the fluid under the microscope to see if any infection or cancer cells are present. It is also used to give anticancer drugs directly to the brain and spinal cord in cases of acute laekaemia. A lumbar puncture is not dangerous, as long as the doctors and nurses carrying it out follow the correct procedures. These procedures include checking that there are no contraindications (such as a sudden rise in pressure in the brain or an abnormality in the way in which blood clots). The doctors and nurses will take precautions to prevent any infection entering the body during the lumbar puncture. The spinal cord cannot be injured by a lumbar puncture which is properly carried out, as the needle enters the spine below the lower end of the spinal cord. The small amount of fluid which is removed is very quickly replaced by the body.
• Tissue biopsy – A small sample of tissue is taken from the organ suspected to be involved by the tumour. This will be performed either by the surgeon who will make a small incision (open biopsy) or a radiologist who will insert a needle into the affected organ under ultrasound guidance (close biopsy) The tissue will then be sent to a histopathologist who will carry out tests to determine what is the tumour type, and whether it is cancerous (malignant) or not cancerous (benign).
• Ultrasound – Ultrasound obtains a picture of part of the body by using sound waves. The waves echo or bounce off tissues and organs, making pictures called sonograms. Tumors have different echoes compared to normal tissues, making it possible to “see” abnormal growths.
• CT scan (computerized tomography scan) or CAT scan-This test obtains a three-dimensional picture of organs and tissues; ordinary x-rays give a two-dimensional view. Using pencil-like x-ray beams to scan parts of the body, a CT also gives better pictures of soft tissues than does an x-ray. It provides precise and very useful details about the location, size, and type of tumor.
• MRI (magnetic resonance imaging)- An MRI creates pictures of areas inside the body that cannot be seen using other imaging methods. MRI uses a strong magnet linked to a computer. Because MRI can see through the bone, it can provide clearer pictures of tumors located near the bone.

What are the different types of cancer treatment?

The types of treatment used most often to treat cancer are surgery (to remove cancerous cells or tumors), chemotherapy (the use of medical drugs to kill cancer cells), radiation therapy (the use of radiant energy to kill cancer cells) , and bone marrow or peripheral blood stem cell transplantation. Doctors use these treatments to destroy cancer cells.

Depending on the type of cancer, children may have one kind of treatment or a combination of treatments.

Surgery

For many solid tumors, surgery is an essential part of the treatment. Surgery is a local therapy to remove the tumor. Tissue around the tumor and nearby lymph nodes may also be removed during the operation.

Sometimes radiation or chemotherapy is used first to shrink the tumor before it is removed. Shrinking the tumor makes the surgery easier.

What is chemotherapy?

Depending on the type of cancer the child has and which drugs are used, chemotherapy may be given in one or more of these ways:

• By mouth (oral medication) – The drugs are swallowed in liquid or pill form.
• Intravenously (IV) – The drugs are injected by needle into a vein or into an IV line.
• Intramuscular injection (IM) – The drugs are injected by needle into the muscle.
• Subcutaneous injection (SC) – The drugs are injected by needle just below the skin.
• Intrathecal injection (IT) – The drugs are injected by needle into the spinal fluid

The duration of chemotherapy treatment and type of drugs that are used depend on the type of cancer the child has and his or her response to the drugs. Every child’s treatment differs, so a child may receive daily, weekly, or monthly chemotherapy treatments.

What are side effects of chemotherapy?

Many of the medications used in chemotherapy carry the risk of both short-term and long-term problems. Short-term side effects include nausea, vomiting, hair loss, fatigue, anemia, abnormal bleeding, and increased risk of infection due to temporary suppression of the immune system and of the bone marrow, as well as impairment of kidney and liver function.

Some drugs carry a risk of urinary bladder inflammation and bleeding into the urine, and hearing loss. Others may cause heart and skin problems.

The potential side effects of the various drugs that will be given to the child will be explained to the parents at the start of therapy. Whether the child will experience these side effects and the degree of severity of these side effects will, to a certain extent depends on his or her body’s response to the chemotherapy. Every child will react differently.

However, precautions will be taken and the child will be assessed clinically and biochemically before each course of chemotherapy. In addition there are medications that can be used to counteract some of these side effects.

Radiation therapy

Radiation is one of the most common treatment for cancer. When a child receives radiation therapy, he or she is treated with a stream of high-energy particles or waves that destroy or damage cancer cells. Many types of childhood cancer are treated with radiation, in conjunction with chemotherapy or surgery.

Like surgery, radiation therapy is a local therapy. The rays are aimed at the part of the body that has cancer, and the treatment destroys cancer cells in the treated area. Doctors may use radiation therapy before surgery to shrink a tumor. After surgery, radiation therapy may be used to stop the growth of cancer cells that remain.

What are side effects of radiation therapy?

Radiation has many potential side effects (such as increased risk of future malignancy and infertility), which you should discuss with your child’s doctor. The primary goal when treating children with cancer is to cure them; this takes priority over all other aspects of care. However, there are many medications and therapies that can make children more comfortable while undergoing treatment for cancer.

What is bone marrow and Peripheral Blood Stem Cell Transplant?

Some children who have leukemia or other types of cancer may need a bone marrow transplant (BMT) or a peripheral blood stem cell transplant (PBSCT). In these treatments, the blood cells in the diseased or damaged bone marrow – the spongy material that fills the inside of bones and makes blood cells – are replaced with healthy cells (stem cells), which will grow new healthy cells.

Two circumstances create the need for a transplant. The first is when the cancer itself has injured the bone marrow. BMT and PBSCT are commonly used in the treatment of leukemia and lymphoma. The second circumstance is when a treatment requires such large doses of chemotherapy or radiation therapy that the child’s bone marrow is damaged during treatment.

Conclusion

The diagnosis and treatment of childhood cancers takes time, and there are both short-term and long-term side effects. But thanks to medical advances, more and more children with cancer are finishing successful treatment, leaving hospitals, and growing up just like everybody else. Today, up to 70% of all children with cancer can be cured.