Pediatric Radiation Therapy - Children's Radiation Treatment

Every rule in children's radiotherapy comes down to one aim. The lowest dose that cures, to the smallest volume, and nothing more.

A child's brain, bones, glands and heart are still growing, and radiation that an adult would shrug off can change a child's height, hormones, hearing or school performance for life. So pediatric radiotherapy follows different rules, comes from teams that treat children every day, and gets watched for decades afterward. The rules work. Among 34,033 survivors of childhood cancer, deaths in the fifteen years after the five-year mark fell from 12.4 percent for children treated in the early 1970s to 6.0 percent for those treated in the 1990s, and lower radiation doses were a large part of the reason.

What makes radiotherapy different in a child

Radiation does the same thing in a child as in an adult. It damages the DNA of dividing cells, and tumor cells divide fastest. The difference lies in the tissue around the tumor. A six-year-old's brain is still laying down the circuits for reading and arithmetic, the growth plates of the spine and limbs are still open, the thyroid, the pituitary gland and the ovaries or testes are still forming, and every one of them is made of dividing cells too. A dose that leaves an adult's brain unchanged can cost a young child points of IQ every year for a decade, and a dose to the spine that an adult would not notice can shorten a child's final height by several centimeters.

Four rules follow from that. Doctors give the lowest dose that trials have shown to cure, and they have spent forty years finding out how low it can go. They draw the smallest volume that contains the tumor and its likely spread, on MRI, to the millimeter. They reserve radiotherapy for tumors that chemotherapy or surgery cannot handle alone, so children with leukemia, once nearly all irradiated, rarely are today. And when a child's age and tumor put the brain or the spine in the beams, proton therapy, which stops at a set depth and spares the tissue behind the target, is considered before X-rays.

Which tumors, which schedules

Fewer children are irradiated every decade

Cranial radiotherapy for acute lymphoblastic leukemia fell from 85 percent of children in the 1970s to 19 percent in the 1990s, abdominal radiotherapy for Wilms tumor from 78 to 43 percent, and chest radiotherapy for Hodgkin lymphoma from 87 to 61 percent. Armstrong and colleagues, N Engl J Med, 2016.

The tumors that still need radiotherapy, and the schedules used for them, come from cooperative trial groups in North America and Europe that treat thousands of children on shared protocols. The table gives the common ones.

This table scrolls sideways on a narrow screen. Swipe or drag to see every column.

What the long-term studies show

Lowering the dose without losing the cure

Medulloblastoma, the commonest malignant brain tumor of childhood

Whole-brain and spine radiotherapy for medulloblastoma once used 36 gray, and Packer and colleagues asked whether 23.4 gray with chemotherapy would cure as many children, which was a real gamble with a cancer that kills when it returns.

81 percent free of disease, 86 percent alive at five years

Among 379 children aged 3 to 21 with average-risk medulloblastoma treated with 23.4 gray to the brain and spine, a boost to the tumor bed and chemotherapy. Age, sex and the chemotherapy regimen made no difference. Packer and colleagues, J Clin Oncol, 2006.

What the lower dose still costs

Intelligence and school skills

Even at 23.4 gray the brain pays. Mulhern and colleagues tested 111 children with medulloblastoma repeatedly for up to six years after diagnosis.

1.59 IQ points a year

The average decline in IQ, with reading falling 2.95 and spelling 2.94 points a year, after risk-adapted radiotherapy for medulloblastoma. Children under 7 at diagnosis and those on the higher dose lost the most. Young age was the strongest risk factor. Mulhern and colleagues, J Clin Oncol, 2005.

Where protons make a measurable difference

The same protocol, two kinds of beam

Kahalley and colleagues followed 79 children with medulloblastoma treated on the same protocols at the same dose, 37 with protons and 42 with X-rays, for a mean of 4.3 years.

Stable IQ with protons, a decline with X-rays

The proton group held steady in global IQ, perceptual reasoning and working memory, while the X-ray group declined in global IQ, working memory and processing speed. Processing speed fell in both groups. Kahalley and colleagues, J Clin Oncol, 2020.

The long view, thirty years on

Why follow-up never ends

The Childhood Cancer Survivor Study follows people treated for cancer before the age of 21 in the United States and Canada. Today's doses owe their size to it.

62.3 percent had a chronic condition, 27.5 percent a severe one

Among 10,397 adult survivors treated between 1970 and 1986, compared with their siblings. Thirty years after diagnosis the cumulative figure reached 73.4 percent. Oeffinger and colleagues, N Engl J Med, 2006. The later analysis by Armstrong and colleagues showed that children treated in the 1990s with lower doses were dying of late effects far less often.

How to read these numbers

Two of these studies describe children treated in the 1970s and 1980s with doses and volumes that no protocol uses today, and the reduction in late deaths across the decades is the measure of what changed. None of them describes one child. A parent who reads them should take away three things. Radiotherapy cures most children who need it. Doctors keep the dose as low as the cure allows, for reasons the studies make plain. And a child who has had it needs a follow-up plan for life.

Keeping a child still, from play to anesthesia

A radiotherapy plan is accurate to a millimeter or two, and a child who moves that much receives the dose in the wrong place. How the team gets a child to lie still depends on age and temperament more than on anything medical.

• Children of about six and older usually manage awake. A play specialist or child life therapist explains the machine with a model or a doll, the child visits the room and lies on the couch before the first session, and a favorite cartoon plays on a screen or through goggles during treatment. The mask, molded in warm plastic, is decorated by the child before it hardens
• Children under about five, and older children who cannot manage, have a short general anesthetic for every session, given by a pediatric anesthesiologist with propofol through a small line that stays in place for the course. The child is asleep for 20 to 30 minutes, wakes in a recovery room with a parent, and eats and plays within the hour
• Daily anesthesia means daily fasting, which for a small child is planned to the hour, with the earliest slot of the morning given to the youngest patients so that nobody is hungry for long
• A parent stays in the room until the child is asleep and is beside the bed when the child wakes. During the treatment itself everyone leaves the room, and staff watch by camera
• Many children who start with anesthesia manage awake by the third or fourth week once the routine is familiar, and the team tries that when the child is ready

A course of treatment, day by day

1. Consultation. The radiation oncologist, the pediatric oncologist and, for brain tumors, the neurosurgeon agree the dose and the volume from the protocol the child is on. Parents hear what the treatment will and will not do, and the child hears an honest version suited to their age.
2. Preparation. Blood tests, a hearing test if cisplatin has been given, growth and hormone baselines, and a neuropsychological baseline for any child whose brain will be in the beams, so that later changes can be measured against it.
3. Mask and planning scan. A CT in the treatment position, fused with the MRI, under anesthesia if the child needs it. The doctor outlines the target and every growing structure to protect, and the physicist builds the plan over three to seven working days.
4. Sessions. The same time each day, the same staff, the same routine. A sticker chart, a bead for each session, or a countdown on the wall, because children do better when they can see the end.
5. Weekly review. Weight, blood counts, skin, appetite, sleep and mood. Chemotherapy given alongside is coordinated with the pediatric oncology team on the same site.
6. Last day. A bell to ring, a certificate, and a treatment summary that the family will keep for the rest of the child's life.

Side effects now and side effects later

This table scrolls sideways on a narrow screen. Swipe or drag to see every column.

When the plan changes

Children's protocols run to a calendar, and radiotherapy has its slot in it. A chest infection, a fever on chemotherapy or low blood counts can push that slot back by days, and a course already started continues through minor illness unless the child is unwell enough for admission. When a child is admitted, the daily session continues from the ward. Anesthesia occasionally has to be adjusted or, for a child who has become anxious, reintroduced. The MRI taken for planning sometimes shows more or less tumor than the referring scan, and the volume is redrawn before the first session rather than after it. All of this happens within one building, because the pediatric oncology ward, the anesthesia team and the radiotherapy department at Biruni Hospital share a site, and a decision that needs three specialists is taken in one meeting on the same day.

Weeks in Istanbul, cost and the family

The length of stay depends on the tumor.

One to eight weeks, by tumor

Wilms tumor needs one to two weeks including planning. Hodgkin lymphoma needs three to four. Sarcomas need five to seven. A brain tumor needs seven to eight, and children who receive chemotherapy in the same weeks stay for the chemotherapy calendar as well. A child under anesthesia adds no days, only hours.

The length of stay comes from the table above. Cost depends on the number of sessions, whether anesthesia is needed every day, the planning imaging, the mask, the baseline tests, chemotherapy given alongside, and any admission. Daily anesthesia separates a small child's course from an older child's, since every session needs an anesthesiologist, a nurse and a recovery bed. Published packages for children in Istanbul cover the consultation, planning, all sessions, weekly reviews, an interpreter and transfers, and leave out chemotherapy drugs, anesthesia in some cases, the hotel and flights, so ask whether anesthesia is inside the figure. A quote follows the doctor's review of the protocol and the scans, and that review is free.

Families stay together. An apartment near the hospital for two parents and siblings works better than a hotel room over six weeks, and the international patients office arranges it, along with the airport transfers, the daily rides and the invitation letter that goes out with the appointment confirmation ten days before travel, naming the hospital and the treating doctor and stating the length of treatment for the visa. One coordinator handles the case from the first message, in English, Arabic, French, Russian, Serbian, Romanian or Spanish, or through an interpreter, and a child who speaks none of those is helped by a play specialist for whom language matters less. Both parents may attend consultations. If the child is admitted, one parent sleeps in the room. Halal, vegetarian and diabetic meals are available, a prayer room is on site, and a female doctor can be requested when you first write.

After you fly home, for the next thirty years

The treatment summary is the most important document the child will ever own

It states the tumor, the dose to every organ that was in or near the beams, the dates, the technique and the chemotherapy given. Every doctor who sees the child in the next thirty years needs it, from the pediatrician measuring height to the cardiologist checking the heart, and the family should keep a copy in two places.

Pediatric Radiation Therapy - Children's Radiation Treatment FAQ