The side effects of surviving childhood cancer

SINGAPORE - Ms Rachel Chin is all grown up now and raring to get on with her life.

She will soon be starting a distance learning degree in events management with the Southern Cross University in Australia.

Looking at her now, it is hard to imagine the suffering she has had to endure since she was diagnosed with leukaemia at 3 1/2 years old.

The effects from the cancer treatment have lessened over the years but, in the beginning, they were "horrible", she recalled.

Ms Chin, who will be turning 21 later this year, is matter-of-fact about the problems which began after her bone marrow transplant: skin rash, mouth ulcers, sore eyes and extreme sensitivity to the sun.

Ms Chin had two relapses of her cancer before she received a bone marrow transplant at the age of 12.

She missed about a year of school after the transplant, but was able to keep up academically.

Her late effects are primarily related to the cumulative chemotherapy she underwent after she was diagnosed with leukaemia and the transplant, said her physician, Dr Tan Poh Lin, senior consultant at the division of paediatric haematology-oncology at the National University Hospital.

When Ms Chin could go back to school, there would be many days she felt good enough to do so initially, but would have to turn back during the car ride there.

"My eyes would swell up and tear badly and I would not be able to see. My mum would have to take me home," said Ms Chin.

The skin rash would erupt just as suddenly. But, by far, the worst late effect was mouth ulcers.

Ulcers would crop up inside her mouth and be so painful that she would not be able to open her mouth.

"Even air would hurt my mouth," she said.

The effects would occur at different times.

The rashes, sore eyes, sun sensitivity and mouth ulcers are the effects of graft-versus-host disease (GVHD), in which the donor's cells mount an attack on the recipient's cells.

Dr Tan said: "Ironically, the GVHD provided the graft versus leukaemia effect that is most powerful in controlling the stubborn leukaemia, which clearly chemotherapy could not cure in her case."

What it means is that for a person having a transplant for leukaemia, having mild GVHD may be a good thing. As well as attacking the body cells, the donor white blood cells from the bone marrow will also attack any remaining leukaemia or cancer cells. Doctors call this the graft-versus-disease effect, or graft-versus-leukaemia effect.

GVHD is an unfortunate effect of the cure. Chronic GVHD happens in about 30 per cent of patients who receive unrelated donor transplants, added Dr Tan.

It can affect any organ, commonly the skin (rash, often like sunburn), gut (mouth sores, abdominal pain, diarrhoea, nausea or vomiting), liver (jaundice or yellowing of the skin), lungs (blocked airways) or eyes (irritation and light sensitivity).

It can be debilitating because of organ injury or infections. But if detected and treated early, it is generally not life-threatening, said Dr Tan.

Ms Chin's oral ulcers and skin rashes tended to occur during times of stress, such as school examination periods.

Steroid pills helped to keep those in check. She now also has a steroid mouth wash and cream to control the ulcers.

She has to have her eyes checked regularly. One of the side effects of long-term steroid use is cataracts, a disease in which the lens of the eye gets clouded, obscuring vision.

Her late effects have occurred nearly every year and now there remains a single mouth ulcer which will not go away.

"But I'm used to it," she said.

Over the past few years, her ears, heart, lungs, kidneys and hormones have also been checked regularly at the late effects service at the NUH, and she will continue to go back for more follow-ups.

"So far so good. I'm normal for everything so far except the GVHD," she said, noting that her height at 1.65m is considered normal.

A long journey of after-effects

A long journey of after-effects

One of the more common late effects of paediatric cancer treatment is hormone disturbance.

This problem can affect up to four in 10 patients, said Associate Professor Loke Kah Yin, head and senior consultant at the division of paediatric endocrinology at National University Hospital (NUH).

How and where these disturbances begin is related to the type of treatment, the age of the patient and the length of time since the treatment.

For example, irradiation to the head and neck can affect hormones that regulate puberty, said Prof Loke.

Irradiation to this area may damage the pituitary gland which produces hormones that regulate many processes, including growth and maturation.

Low doses of irradiation may result in early or precocious puberty and higher doses may result in delayed puberty.

The irradiation may prompt the premature secretion of sex hormones that leads to precocious puberty, occurring before the age of eight years in girls or the age of nine years in boys.

Dr Loke said: "This can result in a premature growth spurt and early fusion of their bones. These children may be tall initially from the early growth spurt. However, if they are not treated, they will be significantly shorter than their friends."

This is because sex hormones cause bones to fuse and growth is stopped.

Moreover, children who mature early may behave inappropriately because they become sexually aware earlier.

Girls may experience early menstruation, which can be frightening for her and her parents.

Conversely, children who have delayed puberty may be taller than their peers as there is a delay in the secretion of sex hormones needed for bones to fuse and stop growing.

Medication can be used to treat precocious and delayed puberty, so early detection is important.

Another issue is fertility, though this surfaces mostly when child survivors become adults.

Dr Cindy Ho, associate consultant at the division of paediatric endocrinology at NUH, estimated that about 20 to 30 per cent of female paediatric patients are at risk of early menopause.

Sometimes, it can occur before 40 years of age, she said.

Some children whose cancer requires radiation to the pelvic region may also inadvertently get radiation to the uterus that may shrink it and the blood supply to it.

"Studies have shown placental abnormalities. They are more prone to miscarriages, having smaller babies and the risk of premature births," said Dr Ho.

Some types of chemotherapy can be toxic to the testes and ovaries and affect the egg and sperm production leading to sub-fertility or infertility, said ProfLoke.

The testes are very sensitive to irradiation and the germ cells that will form the sperm can be damaged even from very low levels of irradiation, he said.

These issues should be discussed with adolescents and their families.

Adolescents who have passed puberty are advised to consult fertility experts before their cancer treatment starts, to discuss the possibility of preserving their eggs and sperm, said ProfLoke.

Specialist help needed

Specialist help needed

Cancer treatment involving the head and neck can also increase the risk of eye problems, said DrInez Wong, a consultant at the division of ophthalmology at NUH.

These types of treatment include high doses of radiation to the brain, eye or eye socket, radio-iodine treatment for thyroid cancer and certain chemotherapy drugs given with radiation.

"Some of these problems include blurred vision, dry eyes, increased tearing, glaucoma, cataract, sensitivity to light and pain in the eye," Dr Wong said.

It is important for cancer survivors to visit their eye specialist at least once a year for a vision screening and eye examination.

Some types of cancer treatment - such as certain kinds of chemotherapy and other medication, high doses of radiation to the head or brain, and surgery involving the brain, ear or auditory nerve - can also damage hearing.

"Symptoms include tinnitus or ringing in the ears, dizziness and high frequency hearing loss," said Dr Loh Woei Shyang, senior consultant at the department of otolaryngology - head and neck surgery at NUH.

If the cancer treatment affects the ears, it is important to have an ear, nose and throat specialist review the patient's hearing, he said.

Tools such as hearing aids or cochlear implants can help the patient to communicate. Other forms of therapy such as speech therapy may also be helpful.

Children may experience developmental dental problems if they have cancer treatment before the age of 12.

There may be abnormal tooth formations such as shortened roots, small teeth and delayed tooth eruptions, said Dr Catherine Hong, consultant at the discipline of orthodontics and paediatric dentistry at NUH.

Other dental problems which affect cancer patients of all ages include dry mouth and subsequent risk of extensive dental decay, oral ulcers and alterations in taste.

Treatment varies and may range from routine restorations to use of topical medication to relieve oral signs and symptoms.


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