Proton therapy has proven to be effective in treating pediatric cancer. It is a powerful treatment option that minimises the chances of damaging surrounding vital organs or tissues while targeting the tumour cells. It is an effective treatment option for certain childhood cancers that affect the brain, neck and spine. If you are considering a treatment that reduces long-term side effects, this article will help explain why proton therapy might be the right choice for your child or loved one. If you are curious as to why Proton therapy works differently from other treatment options keep reading.

Introduction 

Proton therapy is a form of radiation that uses a high-energy beam called proton. Protons are small particles or components of an atom.1 The use of proton for cancer treatment allows a dose of high-energy proton to accurately target a tumour while reducing the damage to surrounding healthy organs and tissues.1 Proton therapy is suitable for cancers of the brain, head, neck and cancers that start in the body's connective tissues such as muscles, bone, fat or blood vessels known as sarcomas.

Proton therapy and X-ray radiotherapy share some similarities which include, both being painless and having similar side effects.¹

In terms of differences, it is generally established that proton therapy is safer than traditional X-ray radiotherapy, proton therapy is also more expensive and has fewer side effects than X-ray radiotherapy.²

Pediatric cancer also known as childhood cancer is cancer that occurs between age 0 to 14 years.³ Pediatric cancer is one of the leading causes of death in kids globally as it affects many children and families.⁴ The most common pediatric cancer is acute leukemia which accounts for about 28% of all childhood cancer cases.⁴ Brain and spinal cord tumours ranks second accounting for 26% of pediatric cancer cases.⁴ Neuroblastoma (NB) ranks the third most common childhood cancer, making up 15% of all pediatric cancer deaths with a 5-year survival chance of less than 50%.⁵

Despite the improvement of medical research and treatments, fighting childhood is still a matter of concern and urgency as it has been difficult to combat.⁴ It is important to treat pediatric cancer to improve health outcomes of affected kids, their quality of life and enable them to attain their full potential.⁶ When treating pediatric cancer with radiation (proton therapy) it is essential to find a balance between treating the tumour and completely reducing the harmful side effects radiation can cause.⁶

Proton radiation can damage healthy organs and tissues even when administered at low doses and may increase the risk of another cancer developing later in life.⁷ For children less than ten years of age, little doses of radiation to the brain can cause prolonged learning and behavioural conditions. This is because children are still undergoing the developmental growth which makes them more sensitive to radiation than adults.⁸

How proton therapy works

The device used for proton therapy is known as cyclotrons and synchrotrons.⁹ There are 2 major methods of delivering proton treatments:

• Passive beam scattering
• Dynamic spot scanning

Passive beam scattering is a simpler method that operates by spreading the proton over the tumour effectively and it is the most common method used in clinics recently. Passive beam scattering can either be single or double scattering. Single scattering is suitable for targets with little extent in depth such as the pituitary(master) gland.⁹ To reduce the loss of energy and improve efficiency while administering proton therapy, double scattering was developed.

The advantages of a passive scattering system are; its safety, simplicity and sensitivity to lower energy. The disadvantages include low level of efficiency about 20-40% which results in wastage of large numbers of protons. The production of large numbers of protons can result in secondary neutrons leading to increased chance of secondary tumour.¹⁰ Therefore Passive scattering system may not be the best option for treating irregular-shaped tumours close to sensitive areas.

Dynamic spot scanning is a more advanced method because it works more precisely in ensuring that the target tumour gets the right amount of radiation. It operates by painting the tumour with protons in small spots, offering better control but it is more complicated.9 It operates using two scatters: the first spreads out the proton beam while the second scatter modifies the proton to create an even or flat distribution of radiation on the tumour.¹¹ However, if a slight shift in the beam occurs, the distribution can become uneven which is a limitation of this method.

Clinical treatment outcomes of proton therapy

Central nervous system tumour 

Proton therapy has proven to be effective in treating a type of brain tumour known as medulloblastomas because these tumours often spread throughout the brain and spine of affected children.^12,13 Therefore proton therapy offers protection of healthy tissues surrounding the tumour, which lowers the risk of recurring cancer later in life.

Ependymomas 

These are more common brain tumours in children under 10 years old. The chances of survival increase when the tumour is first removed by surgery and followed by targeted radiation to the brain.14 According to various research there is an agreement that using proton therapy post-surgery for ependymomas is safe and effective, with low side effects.

Sarcomas

Sarcomas are a group of cancer that starts from soft tissues such as muscles (84%) or in the bones (14%).¹⁵ Sarcomas affects all age groups however it is more common in children. Recently proton therapy has been adopted in treating sarcomas to help reduce side effects and the risk of irradiating surrounding healthy organs near the tumour. Although the use of proton therapy for treating sarcomas is still very new and under research results so far are promising for children.¹⁶

Retinoblastoma (RB)

RB is the most common cancer of the eyes among children, it occurs either occasionally or due to hereditary. In about 60 to 70% of the cases it affects one eye and both eyes in about 30 to 40% of cases.¹⁷ Radiotherapy has been known to be effective in treating RB but with an increased risk of secondary cancer developing especially in children that have acquired RB genetically. Therefore radiotherapy is now used only when other treatment options have failed or for a very big tumour.¹² The use of Proton therapy in RB treatment has shown effectiveness in treating tumours compared to traditional radiotherapy.

Limitations of proton therapy

• Proton therapy is more expensive than regular radiation treatment because it requires a very specialised and expensive equipment. The cost of running the machine is also high these includes the machines to speed up the protons, systems to guide the proton beams and large structures to move the beam around the patient all these are factors that make the cost of treatment higher
• Currently, there is a limited long-term data and studies on the effectiveness of proton therapy in treating pediatric cancer
• Not all pediatric cancer can be treated with proton therapy such as the case of diffuse tumour type
• There is also a limited availability of proton therapy centres globally, particularly in low and middle-income countries¹⁸

Future advancement in proton therapy for pediatric cancer

• Potential for proton therapy to be combined with other forms of treatment such as chemotherapy and immunotherapy
• Expanding access and reducing treatment cost
• Updates on ongoing clinical trials exploring new indicators for proton therapy in pediatric cancer
• Research on how to minimize more side effects and improve outcomes

FAQs

How long does proton therapy treatment take?

Could be a daily treatment that lasts for several weeks.

Is proton therapy treatment covered by insurance?

This depends on the insurance plan, always check with your insurance provider.

Is proton therapy expensive?

Yes, it is expensive because of the specialized equipment used.

How can I know if proton therapy is right for my child?

Consult with a pediatric oncologist to determine if proton therapy is the best option for your child.

Why is proton therapy good for children?

It reduces the chances of getting healthy organ damage, which lowers the possibility of long-term side effects in the growing bodies of children.

What kind of pediatric cancer can proton therapy treat?

• Brain tumours such as; medulloblastoma, ependymoma, germ cell tumours
• Cancer of the head and neck,
• Sarcomas such as Ewing sarcoma
• Lymphomas
• Spinal cord tumours
• Neuroblastoma among others

Is proton therapy painful?

No, proton therapy is painless.

Summary 

Proton therapy is a unique type of radiation treatment that is particularly helpful for treating cancer in children because of its precision. Unlike traditional radiotherapy, proton therapy targets tumours more accurately with little chance of damaging surrounding healthy organs or tissues. These reduce the risk of long-term side effects and help improve the quality of life of young children. Proton therapy can either be administered using the simpler passive beam method or more advanced dynamic spot scanning. Although it is more expensive and not easily accessible, it offers significant benefits by lowering the chances of future health problems and increasing the possibility of the survivors attaining their full potential.