How does proton beam therapy work?
Traditional radiotherapy uses photon beams, while proton therapy uses proton beams. Both are forms of ionising radiation that work by damaging cancer cells so they cannot reproduce and eventually die.
The key difference: photon beams travel through the body and exit on the other side, whereas proton beams stop at a specific depth within the tissue. This allows precise treatment of the tumour while limiting the dose received by surrounding normal tissues.
Why is proton beam therapy used?
Many patients choose proton beam therapy because it leads to less radiation exposure to healthy tissues around the cancer. For most cancers in young adults and children, proton therapy is preferred.
For example, in mesothelioma treatment, proton therapy greatly reduces the radiation received by the heart, lungs, and oesophagus compared to conventional photon radiotherapy, resulting in fewer reported side effects.
Who is an ideal candidate?
While suitable for all ages, proton beam therapy is particularly well-suited to children, teenagers and younger adults, where the risk of damaging developing cells is greatly reduced.
Adults can also benefit, particularly in cases where:
- Serious risk of health problems from traditional radiotherapy side effects
- A cancer has returned after receiving traditional radiotherapy
- Standard radiotherapy has not been effective and larger doses are now required
- A cancer has been found in a difficult-to-treat location
The process
Planning
An extensive planning phase ensures the proton beam can be directed precisely at the cancer site. This includes CT imaging, sometimes MRI, and small skin markings to improve positional accuracy.
Treatment
A gantry directs the proton beam to the treatment area. The energy destroys affected cells at the cancer site and stops, causing minimal damage to adjoining healthy cells. Patients are monitored throughout.
How long does it take?
A typical proton therapy course lasts 3 to 7 weeks depending on the cancer type and stage. Most patients attend 5 days per week (Monday to Friday), with each session lasting 30 to 60 minutes. Accommodation is available for patients who travel.
Benefits of proton beam therapy
- Higher radiation doses can be directed at certain tumours, potentially improving long-term tumour control and cure rates.
- Greatly reduces the risk of second cancers caused by radiation, particularly important in children and young adults.
- Incredible precision around critical organs like the lungs, minimising damage to healthy cells.
- Delivers the precise dose needed to destroy the tumour with fewer long-term side effects and improved quality of life.
What types of cancer can it treat?
Proton beam therapy is recommended where reducing side effects is a high priority. It is effective for specific lung cancer types including small cell lung cancer in early-stage patients and locally advanced lung cancers.
It is particularly useful for treating mesothelioma and cases requiring radiotherapy following surgery involving the thymic gland.