Although childhood cancer is rare, approximately 13,000 children under the age of 20 are diagnosed with cancer every year. Cancer affects people regardless of age, sex, race, geographical location or social status. Oncology, the study of cancer and tumors, has made significant progress in the prevention, treatment, and prognosis of many childhood cancers. Despite this progress, cancer is the third most common cause of death in children ages 1 to 19. Childhood cancer varies from adult cancers in development, treatment, response to therapy, tolerance of therapy, and prognosis. Learn more about our cancer clinical trials and what makes us the region's top provider of pediatric cancer care.
What is cancer?
Cancer is an abnormal growth of cells. Cancer cells rapidly reproduce despite restriction of space, nutrients shared by other cells, or signals sent from the body to stop reproduction. Cancer cells are often shaped differently than healthy cells, they do not function properly, and they can spread to many areas of the body. Read about certain types of cancer.
Tumors can be benign (non-cancerous), or malignant (cancerous). Benign tumors tend to grow slowly and do not spread. Malignant tumors grow rapidly, can invade and destroy nearby normal tissues, and can spread throughout the body. The term "cancer" is used when a tumor is malignant.
Cancer is malignant because it can be "locally invasive" and "metastatic":
- Locally invasive: the tumor can invade the tissues surrounding it by sending out 'fingers' of cancerous cells into the normal tissue.
- Metastatic: the tumor can send cells into other tissues in the body, which may be distant from the original tumor.
The original tumor is called the "primary tumor." These cells which travel through the body can begin the formation of new tumors in other organs. These tumors are referred to as "secondary tumors." The cancerous cells travel through the blood (circulatory system) or lymphatic system to form secondary tumors.
The lymphatic system is a series of small vessels that collect waste from cells, carrying it into larger vessels, and finally into lymph nodes. Lymph fluid eventually drains into the bloodstream. When cancer spreads, it is still named after the part of the body where it started. For example, if kidney cancer spreads to the lungs, it is still kidney cancer, not lung cancer. (The lung cancer would be an example of a secondary tumor.)
"Staging" is the process of finding out whether cancer has spread and if so, how far.
Causes of cancer
There is no one single cause for cancer. Scientists believe that it is the interaction of many factors together that produces cancer. The factors involved may be genetic, environmental, or constitutional characteristics of the individual.
Diagnosis, treatment, and prognosis for childhood cancers are different than adult cancers. The main differences are the survival rate and the cause of the cancer. The survival rate for childhood cancer is about 79 percent, while in adult cancers the survival rate is 64 percent. This difference is thought to be because childhood cancer is more responsive to therapy, a child can tolerate more aggressive therapy therefore the prognosis is better.
Childhood cancers often occur or begin in the stem cells, which are simple cells capable of producing other types of specialized cells that the body needs. A change in the cell's DNA or mutation is usually what causes childhood cancer. Cancer can occur from environmental exposures to cells over time.
Risk factors for cancer
Some cancers, particularly in adults, have been associated with repetitive exposures or risk factors. A risk factor is anything that may increase a person's chance of developing a disease. A risk factor does not necessarily cause the disease, but it may make the body less resistant to it.
The following risk factors linked to cancer: Smoking, high-fat diet, and working with toxic chemicals may be risk factors for some adult cancers.
Most children with cancer, however, are too young to have been exposed to these lifestyle factors for any extended time.
Family history, inheritance, and genetics may play an important role in some childhood cancers. It is possible for cancer of varying forms to be present more than once in a family. It is unknown in these circumstances if the disease is caused by a genetic mutation, exposure to chemicals near a family's residence, a combination of these factors, or simply coincidence.
Some genetic disorders (i.e., Wiskott-Aldrich and Beckwith-Wiedemann syndrome) are known to alter the immune system. The immune system is a complex system which functions to protect our bodies from infection and disease. The bone marrow produces cells which later mature and function as part of the immune system. One theory suggests that the cells in the bone marrow, the stem cells, become damaged or defective, so when they reproduce to make more cells, they make abnormal cells or cancer cells. The cause of the defect in the stem cells could be related to an inherited genetic defect or exposure to a virus or toxin.
Exposures to certain viruses such as the Epstein-Barr virus (EBV) and human immunodeficiency virus (HIV; the virus which causes acquired immune deficiency, or AIDS), have been linked to an increased risk of developing certain childhood cancers such as Hodgkin's and non-Hodgkin's lymphoma. Possibly, the virus alters a cell in some way. That cell then reproduces an altered cell and, eventually, these alterations become a cancer cell that reproduces more cancer cells.
Environmental exposures such as pesticides, fertilizers, and power lines have been researched for a direct link to childhood cancers. There has been evidence of cancer occurring among non-related children in certain neighborhoods and/or cities. Whether prenatal or infant exposure to these agents causes cancer, or whether it is a coincidence, is unknown.
Some forms of chemotherapy and radiation have been linked to cancer. In some cases, children that have been exposed to these agents may develop a second malignancy later in life. These strong anti-cancer agents can alter cells and/or the immune system. A second malignancy is a cancer that appears as a result from treatment of a different cancer.
Genes and cancer growth
The discovery of certain types of genes, which contribute to cancer, has been an important in the development of cancer research. Over 90 percent of cancers studied have some type of genetic alteration. We are born with some of these alterations, while others are sporadic, which means they occur by chance or occur from environmental exposures (usually over many years). There are three main types of genes that can affect cell growth, and are altered (mutated) in certain types of cancers, including the following:
- Oncogenes - These genes regulate the normal growth of cells. Scientists commonly describe oncogenes as similar to a cancer "switch" that most people have in their bodies. What "flips the switch" to make these oncogenes suddenly become unable to control the normal growth of cells and allowing abnormal cancer cells to begin to grow, is unknown.
- Tumor suppressor genes - These genes are able to recognize abnormal growth and reproduction of cancer cells, and can interrupt their reproduction until the defect is corrected. If the tumor suppressor genes are mutated, however, and they do not function properly, and tumor growth may occur.
- Mismatch-repair genes - These genes help recognize errors when DNA is copied to make a new cell. If the DNA does not "match" perfectly, these genes repair the mismatch and correct the error. If these genes are not working properly, however, errors in DNA can be transmitted to new cells, causing them to be damaged. Usually the number of cells in any of our body tissues is tightly controlled so that new cells are made for normal growth and development, as well as to replace dying cells. Ultimately, cancer is a loss of this balance due to genetic alterations that "tip the balance" in favor of excessive cell growth.
Cancer treatment
There are many ways to treat childhood cancers. Here, some children receive only one type of treatment; for others, the most effective treatment will be a combination of therapies. The treatment each individual receives, and the sequence in which the treatments are given, depend on the type of cancer and the stage of the disease. The stage of disease refers to whether or not the cancer has spread, and if so, how far.
Surgery - There are several different types of surgery that can be performed at the hospital. The three main types of surgery are biopsies, line placements or removals, and the actual surgical removal of the tumor.
Biopsies - A biopsy is used for diagnosis. There are different types of biopsies: excisional, incisional or needle.
- Excisional biopsy - removes the entire tumor, along with some surrounding healthy tissue in order to compare the different types of tissue and determine whether the tumor cells have been all removed.
- Incisional biopsy - a portion of the tumor is removed
- Needle biopsy - when a tiny sample of a tumor tissue is removed with a fine needle, and the contents are sent to the lab for diagnosis.
Line and port placements - Another common type of surgery performed is the insertion or removal of a long catheter that is set into a large vein to deliver medicine or take blood samples; external lines, such as either the Broviac or the Hickman catheter, are positioned outside the skin. While internal lines such as a Port-a-Cath or Mediport are placed under the skin.
Surgery for the insertion or removal of these catheters is always done while the patient is under anesthesia.
Usually, before a patient begins treatment, a central line is inserted. This can eliminate the need for doctors and nurses to access their veins. At the completion of treatment, the central line is removed from the patient.
Tumor removal - When a surgeon removes the tumor, he may also remove some of the surrounding tissue and lymph nodes close to the tumor. All surgeries are done while the patient is under anesthesia.
Chemotherapy
Chemotherapy is the use of drugs to treat cancer cells. Chemotherapy has been used for many years and is one of the most common treatments for cancer. In most cases, chemotherapy works by interfering with the cancer cell's ability to grow or reproduce.
Different groups of drugs work in different ways to fight cancer cells. Chemotherapy may be used alone for some types of cancer or in combination with other treatments such as radiation or surgery. Often, multiple chemotherapy drugs are used to fight a specific cancer. Certain chemotherapy drugs may be given in a specific order depending on the type of cancer it is being used to treat.
While chemotherapy can be quite effective in treating certain cancers, chemotherapy drugs reach all parts of the body, not just the cancer cells. Because of this, there may be side effects during treatment. Being able to anticipate these side effects can help you and your caregivers prepare, and, in some cases prevent these symptoms from occurring. Your team will help your child with possible side effects of treatment.
How is chemotherapy administered?
Chemotherapy can be given:
- As a pill to swallow
- As an injection into the muscle or fat tissue
- Intravenously (directly to the bloodstream; also called IV)
- Intrathecally (chemotherapy given directly into the spinal column with a needle)
Monoclonal antibodies
Antibodies are made in the laboratory and designed to target specific substances called antigens. Monoclonal antibodies which have been attached to chemotherapy drugs or radioactive substances are being studied to see if they can seek out antigens unique to cancer cells and deliver these treatments directly to the cancer, thus killing the cancer cells without harming healthy tissue. Monoclonal antibodies are also used in other ways, for example, to help find and classify cancer cells.
Radiation therapy
Radiation therapy uses high-energy particles or waves, such as x-rays, to destroy or damage cancer cells. This form of therapy can be used at various phases of cancer treatment. In early stages, radiation therapy may be used to attempt to cure or control the disease. It can also be used before surgery to shrink a tumor, or following surgery to prevent the cancer from returning. In advanced cancers, radiation therapy may be used to treat symptoms that are caused by the cancer, such as pain.
Transplant
The main agents of the body's immune system are red blood cells, white blood cells, and platelets. Stem cells are blood cells that have not decided what kind of blood cell they want to be. All blood cells begin as undecided stem cells. Many of these remain in the bone marrow where they can become any type of blood cell the body needs, but some go into general circulation through the blood vessels.
If someone has a type of cancer that responds to high doses of chemotherapy, radiation, or both, one of the side effects of treatment is that her bone marrow will be suppressed. To help bone marrow cells recover from these intense treatments, bone marrow transplants are performed. There are two common types of transplants: autologous (the stem cell source is the patient herself) and allogenic (the stem cell source is someone else). More here about stem cell transplantation »
Integrative medicine
Integrative medicine works to create a safe, healing medical environment from a holistic perspective that promotes the assessment of integrating non-traditional therapies with conventional practices on the physical, emotional, and spiritual needs of children and their families. More here on integrative medicine »
Note: Patient education is an important part of family-centered care. The resources listed here were created by our nurses to help you better understand your child’s care and are commonly requested by our patient families.