Late Effects of Childhood Cancer Treatment
Around 80% of Children with Cancer survive at least 5 years these days thanks to advances in treatment, and most of those children will continue on to live a normal life-time.
Unfortunately, the selfsame treatments that are helping Children with Cancer to overcome the cancer, are themselves causing various health problems later on in these children’s lives.
Most side-effects from the cancer itself and from the cancer treatments appear during or just after treatment, and go away within a fairly short time. Some problems, however, may never go away or may not show up until months or years after treatment.These problems are called late effects.
Due to the fact that more children with cancer now survive into adulthood, their long-term health and these late effects have become more evident and because doctors are more aware of the late side-effects, they will look out for them in careful follow-ups and can therefore find and treat any late effects as early as possible.
Which Children are At Risk for Late Effects after Cancer Treatment?
Every Child with Cancer that is undergoing cancer treatment is unique; treatments vary from child to child and from one type of cancer to another. Late effects will also vary, and depend mostly on the type of treatment used and the doses given.
Other elements that can affect a child’s risk for late effects include:
- The type of cancer
- Where the cancer was situated in the body
- How old the child was when diagnosed and treated
- The child’s overall health before being diagnosed with cancer
- The child’s genetic make-up (inherited risk for certain health problems)
Cancer treatments kill off cancer cells, but they also harm healthy cells, and Late Effects are caused by the damage that some cancer treatments do to healthy cells in the body.
Late Effects of Childhood Cancer Treatments
Chemotherapy (chemo) is the use of drugs to kill cancer cells. But chemo drugs can damage normal cells, too, which can cause short-term and long-term side effects.
Chemotherapy damage to quickly dividing cells can cause side effects such as low blood cell counts, nausea, diarrhoea, or hair loss during treatment. These short-term side effects usually go away over time after treatment is over.
Late effects, on the other hand, may happen many years later. A child’s whole body is growing. This means that many different kinds of healthy, normal cells are dividing faster than they would be in an adult. Some types of chemo drugs can damage these cells and keep them from growing and developing the way they should.
Radiation Therapy treatment uses high-energy rays to kill cancer cells and shrink tumours. The radiation can either come from outside the body (external radiation) or from radioactive materials placed into or right next to the tumour (internal or implant radiation). Radiation is sometimes used along with other treatments; before or after surgery, or together with chemotherapy treatments. In some cases it may be the main treatment given.
As with chemotherapy, radiation therapy can affect normal cells as well as cancerous cells. Some organs and parts of the body are more likely to be affected by radiation than others. Younger children’s bodies tend to be more sensitive to the effects of radiation, and some children are at greater risk for side effects. Children with the hereditary form of Retinoblastoma (eye cancer), for example, are more sensitive to the effects of radiation.
Surgery is an vital part of treatment for many cancers. As with other types of treatment, the possible long-term effects of surgery depend on various factors.
In some cases, surgery may be fairly minor and may leave nothing more than a scar, while in other cases may call for more extensive surgery and require removing part or all of an organ, or even a limb. Doctors will always do their best to limit the effects of surgery by striking a balance between removing all of the cancer and taking out as little healthy body tissue as possible.
Younger children, whose bodies are still actively growing, may be more affected by some operations than older children who are already at or near their full body size.
Late Effects of Childhood Cancer Treatment on Different Areas of the Body
The treatment of Childhood Cancer requires a very specialised approach because it is not the same as adult cancer, and this counts for the aftercare and watching for late effects in Children with Cancer as well.
Late effects can involve more than one part of the body (or more than one organ system) and can range from mild to severe.
While it is not possible to list all of the possible late-effects of Childhood Cancer and Childhood Cancer Treatments, the following are some of the more common late-effects.
If your child is being or has been treated for cancer, it is important to speak with your child’s healthcare team about the possible late effects based on your child’s specific type of cancer and treatment.
Some treatments used for brain tumours or in an attempt to prevent cancer from spreading to the brain can cause late effects. Children with Brain Tumours or with Acute Lymphoblastic Leukaemia (ALL) are most likely to have late effects in the brain, but children with other cancers may also be affected. Treatments that can affect the brain include Surgery, Radiation Therapy, and Chemotherapy.
Normal brain cells grow quickly in the first few years of life, making them very sensitive to radiation. Doctors will generally attempt to avoid or postpone using Radiation Therapy to the head of children younger than 3 years old in order to limit damage that might affect brain development.
Radiation Therapy may cause problems such as learning disabilities even in older children though. Doctors will always try to use as little radiation as possible, but they also need to balance this with the risk of the cancer growing, spreading or returning, as radiation therapy may be lifesaving in some cases.
Some types of Chemotherapy, given either into a vein (intravenous, or IV chemo) or directly into the spinal column (intrathecal chemo or “spinal tap chemo”), can also cause learning disabilities in children. This is more likely if higher doses of certain chemo drugs are used, and if the child is younger at the time of treatment. Learning disabilities are more common in children who get both chemo and radiation to the brain.
Learning problems, often called Cognitive Impairments, usually show up within a few years of treatment, and may present as:
- Behavioural problems
- Lower academic achievement test scores
- Lower IQ scores, which can vary depending on how intense the treatment is
- Poor hand-eye coordination
- Problems with memory and attention
- Slowed development over time
Non-verbal skills like maths are more likely to be affected than language skills such as reading or spelling, but virtually any area of brain development can be affected.
Other late effects that may occur, depending on the type of treatment used, include seizures and frequent headaches.
Cancer treatments that affect the brain can also lead to other effects in the body; Radiation Therapy sometimes affects the pituitary gland (situated at the base of the brain – helps control hormone levels in the body).
Symptoms of pituitary problems can include fatigue, listlessness, intolerance to cold, poor appetite, and constipation, which may point to low levels of certain hormones. Other problems can include delayed growth and/or sexual maturation, which are described below in the section “Treatment effects on growth and development.”
Childhood Cancer treatment can affect a child’s vision in various ways. Vision problems after treatment are most commonly seen in children with Retinoblastoma, which is a childhood cancer that starts in the retina. The vision in the eye has often already been destroyed by the tumour at the time of diagnosis, which may require that the eye be surgically removed and a prosthetic (artificial) eye put in its place.
Radiation Therapy to the eye can sometimes damage inner parts of the eye, leading to vision problems. Radiation in the area of the eye can also sometimes cause cataracts over time. Radiation treatment to the bones near the eye may slow bone growth, changing the shape of the child’s face as it grows.
Pituitary Gland Tumours or their treatment might also affect vision. This gland is very close to the optic nerves, which connect the eyes to the brain. Surgery or radiation in the area might also affect these nerves, which could lead to vision problems.
Certain Chemotherapy drugs can be toxic to the eye and may lead to blurred vision, double vision, or glaucoma. These effects often disappear over time.
Children who have had a Stem Cell Transplant may be at higher risk for eye problems if they develop chronic graft-versus-host-disease (GVHD) – a condition in which the new immune system attacks cells in the body, including the eye.
Other late effects on the eyes may include:
- Discoloured sclera (white part of the eye)
- Drooping eyelid
- Dry eyes
- Eye irritation (feels like something is in the eye)
- Light sensitivity
- Poor night vision
- Poor vision
- Tumours on the eyelid
- Watery eyes
If the Cancer Treatment your child is undergoing could affect their eyesight, their vision will be checked during treatment so that, if possible, the treatment plan can be changed if there are signs of vision loss. Eye exams will generally also be done regularly after treatment to help find problems. Over time, treatments such as cataract removal or eyeglasses may be needed.
Certain Chemotherapy drugs and Antibiotics may cause hearing loss. Radiation given to the brain or ear can also lead to hearing loss, as can surgery in these areas. The risk may be higher in children who are very young at the time of treatment.
Other late effects of treatment may include:
- Dizziness (if treatment affects the inner ear)
- Hard, crusty earwax
- Ringing in the ears
- Trouble hearing words when background noise levels are high
If your child is getting treatment that might affect their hearing, their medical team will check their hearing during treatment to allow for early changes in treatment if hearing loss becomes a concern.
After treatment, regular hearing-tests can help find any problems. It is important to find and address any hearing issues as soon as possible, as hearing problems in younger children could lead to problems with language development. Older children may experience problems in school or in social situations.
The thyroid gland is an important part of the endocrine system. Hormones from the thyroid affect growth and development in children, as well as help regulate the body’s metabolism.
Thyroid function can be affected by Radiation Therapy or Surgery in the head and neck area, as well as by total body irradiation, which is sometimes used as part of a Stem Cell Transplant. Some treatments damage the thyroid directly, others can damage the pituitary, which in turn affects thyroid function.
Low Thyroid Function (Hypothyroidism) occurs when the thyroid no longer makes enough thyroid hormone. It can cause extreme tiredness, dry skin, unexplained weight gain, constipation, slowed bone growth, poor memory, depression, and thinning hair. Thyroid hormone replacement pills can be given daily to correct this, if needed.
An Overactive Thyroid (Hyperthyroidism) is less likely, but it can happen. Hyperthyroidism can present as nervousness, diarrhoea, weight loss, trouble sleeping, and an enlarged thyroid gland (goiter). If treatment is needed, surgery or radiation may be used on the thyroid gland to lower thyroid hormone levels.
Regular thyroid blood tests can help detect these problems early, often before symptoms appear. Testing is often needed for many years after Radiation Treatment, as sometimes problems may not show up until a decade or more later.
Muscle and Bone
Radiation Treatment can have serious effects on the proper growth of bone and muscle in young people, slowing the growth of any area exposed to it. Bones, muscle, soft tissue and blood vessels are all very sensitive to radiation during times of rapid growth. Young children and children going through a growth spurt at puberty are at especially high risk for effects on growth.
Along with stunted bone growth, other late effects related to bone and muscle problems can include:
- Bone Pain
- Changes in the way the child walks
- Decreased Calcium in the bones
- Increased risk of having a Bone Tumour develop in the area of Radiation Treatment
- Joint Stiffness
- Unequal Growth (the treated side of the body doesn’t grow the same way as the untreated side)
- Weak Bones that can break easily
Certain medications used to treat some types of cancer can also affect the bones, e.g. corticosteroids (prednisone; dexamethasone) are often part of the chemotherapy used to treat cancers such as Leukaemia or Lymphoma. These drugs can sometimes cause osteonecrosis (also called avascular necrosis, or AVN), in which the blood vessels feeding the bones are damaged. This can cause parts of bones to weaken or die, which in turn can cause pain (especially at bone joints) or even breaks in the bone.
Osteonecrosis can affect any bone, but most often it affects parts of bones around the hips or knees. High-dose Chemotherapy as part of a Stem Cell Transplant can also cause osteonecrosis.
Surgery for some types of Childhood Cancers can have obvious effects on muscle and bone growth in certain parts of the body. This is most likely with cancers that start in bones (Osteosarcomas or Ewing Sarcoma) or muscles (Rhabdomyosarcomas).
Some problems in bone growth can be caused by damage to the endocrine system (see “Treatment effects on growth and development” below).
Heart disease can be a serious late-effect of certain cancer treatments. The actual damage to the heart may occur during treatment, but the effects may not show up until many years, or even decades later.
Certain chemo drugs called anthracyclines, used to treat various childhood cancers, can damage the heart-muscle or affect the heart’s rhythm. The amount of damage done depends on the total dose of the drug given and the child’s age at the time of the treatment. Doctors try to limit the doses of these drugs as much as possible while still giving high enough doses to treat the cancer effectively.
Radiation Therapy to the chest or spine and total body irradiation can also damage the heart muscle or cause problems with its rhythm. Radiation can also damage the heart valves or the blood vessels (coronary arteries) that supply the heart muscle with oxygen. The total dose, the type of radiation and the age of the child at the time of treatment all affect this risk.
Most children given these treatments do not develop major heart problems. This is especially true in children being treated today, as modern approaches have reduced treatment doses, which has significantly lowered the risk. Problems are more likely to occur in children who receive more intensive treatment, but doctors cannot always predict who will or won’t have problems.
When cancer treatments do affect the heart, the damage does not usually show up right away, but it can raise the risk of heart problems later in life.
Careful monitoring for heart problems is vital in the years following treatment for Childhood Cancer because there are often no symptoms. Tests such as an EKG or echocardiogram (an ultrasound of the heart), can show hidden problems. Routine physical exams and testing can discover heart problems early on which can be treated if necessary.
Doing things to help keep one’s heart healthy such as maintaining a healthy weight, eating well, not smoking, and getting regular physical exercise is vital for everyone, but especially for those treated for Childhood Cancers.
Certain Childhood Cancer Treatments can affect the lungs. Lung problems can occur in children who have had Radiation Therapy to the chest or Total Body Irradiation. The risk of problems depends on the dose of radiation, how much of the lungs get radiation, and the age of the patient. Certain chemo drugs at the time of radiation may increase the risk.
Possible late effects include:
- Constant cough
- Decreased lung volume (lungs can’t hold as much air)
- Increased risk for lung cancer later in life
- Increased risk of lung infections
- Inflamed lung tissue (called pneumonitis), which can cause trouble breathing
- Lung tissue that becomes scarred and thickened (called pulmonary fibrosis), which limits how much the lungs can expand
- Shortness of breath, which might become worse with exercise
Certain chemotherapy drugs can also cause lung problems, especially fibrosis and pneumonitis. The risk of problems increases with higher drug doses.
Some children who undergo these cancer treatments may have no noticeable symptoms, but for others, problems may start as soon as within the first few years after treatment.
Children who have received these cancer treatments need careful follow-up visits with their oncologist, especially during the first few years after treatment. Chest x-rays or pulmonary function tests may be done regularly in those at high risk for problems.
Keeping the lungs healthy is important for everyone, but it’s especially important in people who had treatments for childhood cancers. The best way to help keep the lungs healthy is to avoid smoking or being around tobacco smoke.
Chemotherapy or Radiation Therapy in an area that involves the teeth and jaw can lead to late effects, mostly in children who are treated before age 5. Older children may also experience problems.
Late effects of these treatments can include:
- Abnormal tooth enamel (teeth may be discolored or not have a normal shape)
- Gum disease
- Increased risk of cavities
- Missing teeth or delayed tooth development
- Short tooth roots (which can lead to early loss of teeth)
- Small teeth
- Teeth that are too sensitive to hot or cold
Radiation in the area around the mouth can also affect the salivary glands, which can lead to decreased saliva and dry mouth. This can cause tooth decay and gum disease.
Regular dental exams are important to find problems early and reduce the risk of infection, decay, and tooth loss.
Late Effects of Cancer Treatment on Children’s Growth and Sexual Development
Slowed growth is a common problem during childhood cancer treatment.
Chemotherapy can contribute to a slow-down in growth – when administered on its own without radiation, the change in growth-rate is most often short-term and many children catch up to a normal growth pattern over time after treatment.
Certain chemotherapy drugs, when given in high enough doses, have more lasting effects; some of the long-term effects of intensive chemotherapy are still unclear.
Many of the late effects on growth and development are linked to Radiation Therapy. Radiation has a direct effect on the growth of bones in the area being treated (see “Muscle and bone”).
Radiation or surgery in the head and neck area can sometimes damage the pituitary gland, which can sometimes affect overall growth and development.
The endocrine system is a group of glands that help control many important body functions including growth, metabolism, puberty, and responses to stress. Endocrine glands include the pituitary, thyroid, adrenals, testicles and ovaries. These glands work by releasing hormones into the bloodstream, which can then affect cells throughout the body. The pituitary releases growth hormone, which stimulates body growth in children. Hormones from the ovaries and testicles affect sexual maturation and fertility.
Hormone changes that result from damage to endocrine glands such as the pituitary can slow the child’s growth and may affect bones, height, and sexual development at puberty – very young children are most likely to be affected. The slow-downof growth is generally seen within 5 years of treatment.
If the pituitary gland is damaged, treatment with growth hormone can often reverse some of the effects on growth, but growth hormone treatment has some risks. The choice to use growth hormone should be made in conjunction with your child’s doctor, and you should fully discuss its possible side effects before embarking on growth hormone treatment.
It’s important for parents of Children with Cancer to discuss all possible long-term effects of cancer treatment on sexual development and fertility with their child’s health care team before starting any treatment, as there may be options for limiting or preventing some of these effects.
Male Sexual Development
In males, the testicles have 2 main functions. They make male hormones (such as testosterone), which influence sexual development and help the body maintain bone and muscle strength, and they also make sperm, which are needed to father children.
Both Radiation Therapy and chemotherapy can reduce sperm production and might also affect sexual development. In general, the cells in the testicles are more likely to be damaged by cancer treatments than the cells that make hormones. These effects may be short-term or long-term, depending on the intensity of the treatment.
Radiation Therapy aimed at the testicles can affect the cells that make sperm. It might also damage the cells that make hormones if given at higher doses. Radiation aimed at the abdomen (belly) or pelvis might also have this effect.
Sex hormone levels in the body are also influenced by the pituitary gland, so radiation therapy to the head area can also affect sexual development and sperm production. High doses of some chemotherapy drugs are more likely to affect cells that make sperm, but very high doses can also affect cells that make hormones.
Treatments that affect sperm production can alter a patient’s ability to father children. This may be only temporary for some, but may be long-lasting or even permanent for others. It’s important to think about this before starting cancer treatment in the older child – sperm banking (collecting and freezing sperm samples) may be an option for boys who have already gone through puberty; it can allow them to father children later in life. The risks of effects on fertility are less in boys who are treated before puberty.
Treatments that affect testosterone levels can cause problems such as failure to complete puberty, early or delayed puberty, and impotence. If needed, doctors can prescribe testosterone in the form of injections, patches, or gels applied to the skin to help maintain normal testosterone levels.
Female Sexual Development
In females, organs important for sexual development and pregnancy include the ovaries and the uterus (womb). These organs can be affected by Childhood Cancer treatments.
The ovaries can be affected by both Chemotherapy and Radiation Therapy. The risk of problems depends on the girl’s age and stage of puberty when they received treatment and the intensity of the treatment. Girls who have not yet been through puberty are less likely to be affected.
Radiation Treatment to the abdomen or pelvis can damage the ovaries, so protecting the ovaries is a major concern when treating nearby areas with radiation. Radiation to the head can also affect the pituitary gland, which in turn can interfere with the hormones needed for the ovaries to work as they should.
High doses of certain chemotherapy drugs can damage the ovaries. In girls who are already menstruating, this can make menstrual periods irregular or stop altogether – this may be temporary or more long-lasting.
Girls who undergo treatments that affect the ovaries are at risk for early or delayed puberty and start of menstruation, irregular menstrual periods, early menopause, reduced fertility, and other health problems. Doctors may recommend hormone replacement therapy to help with some of these issues if they remain after cancer treatment.
The uterus can be affected, too, especially if radiation is given to the abdomen. Late effects can include a uterus that is smaller than normal or which may not stretch during pregnancy as it should. This can increase the risk of miscarriage, low birth-weight babies, and premature birth.
Childhood Cancer Survivors may be concerned about their ability to have children; most of them will be able to have healthy children, although there may be some risks.
Some men who were treated for cancer as children may have decreased fertility due to low sperm counts or other problems. Some of the problems that could affect fertility in women who were treated for Childhood Cancer include irregular menstrual periods, early menopause, and changes in the uterus. Problems can vary greatly from person to person, so careful monitoring for any problems both during and after treatment for Childhood Cancer is critical.
For some who are treated for cancer as children, there may be ways to help preserve fertility or increase the chances of having their own children later in life. Sperm banking before treatment may be an option for some older boys and some women who want to have children may be encouraged to try and get pregnant early in their childbearing years to improve the chances of success. Researchers are constantly studying newer ways of preserving or restoring fertility in survivors of Childhood Cancer.
Most studies have not found an increased risk of congenital (inborn) health problems in the children of Childhood Cancer Survivors.