At the age of nine, Alessandra Samson, apart from being the smallest in her Grade 3 (equivalent to Primary 3) class at United World College, looks like any other child.
Her mother worries she will never catch up with her classmates - with good reason. Alessandra was diagnosed with acute lymphoblastic leukaemia when she was just seven months old.
By the age of two, she had undergone several rounds of chemotherapy and two cord blood transplants. Cord blood, which is blood that remains in the umbilical cord and placenta after birth, contains stem cells which can develop into a variety of cells.
After the gruelling treatment, during which she suffered side effects, such as vomiting, nausea and mouth sores, she went into remission and has remained so since.
But doctors are still keeping a close watch on Ally - as she is known fondly at the National University Hospital (NUH) - especially on her rate of physical growth. Doctors will be doing more tests to check if she is growing at her "genetic potential".
Ally is among a growing pool of paediatric patients here who have beaten their cancer, but are now at risk of what doctors call late effects of cancer treatment, such as chemotherapy, years down the road.
These include low levels of sex hormones (which can lead to delayed puberty), hypothyroidism (low levels of the thyroid hormone, which is important for growth and intelligence), poor bone health and cataracts (clouded eye lenses).
NUH handled 130 new paediatric cancer cases last year, compared with 100 cases five years ago, while KK Women's and Children's Hospital (KKH) now sees about 100 to 120 a year, an increase from about 70 cases a year about five years ago.
The most common childhood cancer here is leukaemia, followed by brain tumour, lymphoma (cancer of white blood cells, usually in the lymph nodes), germ cell tumour (cancer of cells in the ovaries or testes), sarcoma (soft tissue cancer), neuroblastoma (nerve cancer), Wilms' tumour (kidney cancer) and retinoblastoma (eye cancer).
Overseas studies show around 70 to 80 per cent of children and adolescents diagnosed with cancer will become long-term survivors. An estimated 60 per cent of such survivors will develop chronic treatment-related health conditions years or decades after completing treatment. These are known as late effects.
Their general health is also likely to be marginally poorer than that of their peers. For example, their risk of heart attacks would be higher. The causes are multi-factorial, including overprotective parents who prevent them from exercising, which is key in preventing heart disease.
As the number of survivors is expected to increase because of better therapy and higher cure rates, there is a critical need to create the awareness of these late effects, said Dr Tan Poh Lin, senior consultant at the division of paediatric haematology-oncology at NUH.
FOCUS ON LATE EFFECTS
The growing number of childhood cancer survivors led NUH to start a single clinic session for them - involving various specialists, such as endocrinologists, heart and lung specialists, eye specialists and dental surgeons - three months ago.
This makes the late effects service - started in 2000 on an ad-hoc basis and expanded in 2009 by involving more specialists - more convenient for patients as they get to see all the specialists in a single session now.
"It is important for a patient to be monitored and followed up by his oncologist, who will order comprehensive health checks, based on his treatment, type of cancer, age, gender and other factors," Dr Tan added.
Patients can also lower their risk by cultivating good diet and lifestyle habits, for example, eating right, avoiding smoking and limiting the intake of alcohol, she said.
KKH does not have a separate service for late effects but its doctors continue to see patients and monitor them for any late effects of cancer treatment, said Associate Professor Tan Ah Moy, senior consultant at the haematology/oncology service in the department of paediatric subspecialties.
"Late effects are expected and so our care does not stop with the cessation of treatment," she said.
Doctors continue to monitor the height and weight of patients, and screen for their social, psychological and physical well-being.
Paediatric patients may be referred to other relevant specialists, if necessary, Prof Tan said.
All young patients at KKH have consistent follow-up checks and are transferred to an adult hospital if they need treatment then.
Late effects can go undetected initially or it takes time for endocrine deficiencies to manifest, said DrCindy Ho, associate consultant at the division of paediatric endocrinology at NUH.
For example, radiation damage to the pituitary gland - also known as the "master gland" as the hormones it produces control many different processes in the body, including growth and maturation - is indirect and can be very gradual.
It may take up to 20 years after radiation treatment for the full spectrum of hormonal deficiencies to evolve, said Dr Ho.
Studies have shown that some cancer survivors have a slightly higher risk of secondary cancer, due to certain chemotherapy drugs and receiving radiation at a young age, said Dr Tan.
If secondary leukaemia occurs, it is usually within the first 10 years following treatment of the original cancer.
Secondary solid tumours more commonly happen 10 or more years after treatment.
Less than 10 per cent of patients have secondary cancer due to gene mutations.
NUH is currently collecting data on all the different types of childhood cancer, their treatment and the types of late effects caused.
It has found the top five late effects in children who had received a bone marrow transplant and had survived one to five years post transplant.
The results, presented in 2010 at the 15th Congress of Asia-Pacific Blood and Marrow Transplantation meeting in Thailand, showed that six in 10 survivors had iron overload, which has ill effects on the heart and growth.
Four in 10 suffered from poor bone health. Two in 10 had high cholesterol and lipids. Between one and two in 10 were low in thyroid hormone. And six in 100 had cataracts.
WATCHING AND WAITING
Ally crossed the five-year mark after her second cord blood transplant three years ago, said her mother, Mrs Lourdes Samson. The family was originally from the Philippines and are now permanent residents here.
At that point, doctors started doing comprehensive tests, including tests to examine her eyesight, teeth, bones, lungs and heart.
She also had a bone mineral density test to find out how strong her bones were, said Mrs Samson, 42, a housewife.
Before Ally had a transplant, she underwent radiotherapy to kill the cancer cells.
"She had a very small amount of it, but we don't know what the late effects would be," said MrsSamson.
"It's all about her development now and she has had a check-up every year since. So far, everything is good, but we have to keep watch."
The main concern is that the radiation may have affected her physical development.
If Ally, an only child, does not grow normally, doctors may give her growth hormones to help boost her growth.
They will also watch for signs of early or delayed puberty.
NUH's Dr Ho said before the use of growth hormones is considered, the cancer should be in remission.
Most studies have shown no safety issues with long-term use of growth hormones, but there is still limited data and it demands continued surveillance, she added.
"We are hoping for the best for Ally, and if possible, no growth hormones," said Mrs Samson.
This story was first published in The Straits Times on June 13, 2013
To subscribe to The Straits Times, please go to http://www.sphsubscription.com.sg/eshop/