If you are exploring radiotherapy options for yourself or a loved one, this article will introduce you to CyberKnife and proton beam therapy.
In short:
CyberKnife and proton beam therapy are both non-invasive forms of radiotherapy used to treat cancer. CyberKnife is typically used for smaller tumours that move during treatment, and proton beam therapy is often considered when the tumour is near critical organs or where protecting surrounding healthy tissue is a priority.
Please read on to learn how each treatment works, when one may be more suitable than the other, and how doctors determine which, if either, is the most appropriate form of treatment.
If you would like to enquire about private proton beam therapy, please contact Proton International London for advice.
What is CyberKnife therapy?
CyberKnife is a form of stereotactic body radiation therapy (SBRT) sometimes used to treat cancers where breathing causes the tumour to move, such as prostate, lung and liver cancers. In medical terms, ‘stereotactic’ refers to treatments that use three-dimensional imaging to accurately locate a target and guide the treatment, in this case, radiation beams. It does so by using a robotic arm to deliver high doses of X-rays (photons) from many beam angles, with real-time adjustments to account for tumour movement.
The main benefits of CyberKnife are that it allows highly precise targeting while minimising radiation dose to surrounding healthy tissues. It is able to do this by using very narrow treatment margins around the tumour. It is often delivered over fewer sessions than traditional radiation therapy or proton beam therapy. Like other forms of radiotherapy, it is a non-invasive treatment with typically mild side effects. It’s delivered in an outpatient setting, which means that you can return home straight after each session.
What is proton beam therapy (PBT)?
Proton beam therapy is another form of advanced radiation therapy. Rather than using X-rays, it uses protons, which can be carefully controlled to release most of their radiation dose at a specific depth called the Bragg Peak. It deposits most of its energy inside the tumour, thereby reducing radiation exposure to surrounding healthy tissue.
Proton beam therapy is, therefore, particularly helpful for treating tumours close to sensitive organs, such as brain, spinal, head and neck. It is particularly beneficial for young patients, as it minimises radiation exposure to developing tissues.
Because of its precision, proton beam therapy can reduce the risk of side effects during and in the months and years after treatment.
In the short term, PBT can help maintain quality of life; for example, it can protect structures involved in swallowing, speech, or saliva production during the treatment of head and neck cancers. The potential long-term benefits of proton therapy include a reduced risk of secondary cancers in later life, due to the minimised radiation exposure to healthy tissues, though this depends on the individual circumstances.
What proton therapy and CyberKnife have in common:
Both CyberKnife and proton therapy are delivered on an outpatient basis, meaning you can go home straight after the session and get on with normal activities. They are both non-invasive, painless treatments that aim to destroy cancer cells. Both treatments are typically tolerated well at the time of treatment, acute side effects are often mild and can include fatigue and temporary soreness or swelling near the treatment area.
See our page on what to expect during proton beam therapy for more information on side effects.
What is the difference between CyberKnife and proton beam therapy?
Let’s look at the key differences between proton therapy and CyberKnife at a glance:
| CyberKnife (a type of stereotactic body radiation therapy) | Proton Beam Therapy (also called proton beam radiation therapy) | |
|---|---|---|
| Radiation type | X-rays (photons) | Protons |
| Precision | Very high, with real-time motion tracking for tumours that move | Very high, and the radiation stops at the tumour |
| Tumour size | Suitable for small tumours, up to around 5cm | Can treat large tumours, no size limit |
| Typical treatment course | CyberKnife treatments are delivered over a small number of sessions, typically a few days | Proton therapy treatments usually require multiple daily sessions, often taking several weeks to complete. |
| Impact on surrounding tissue | Radiation continues beyond the tumour (an ‘exit dose’), which can expose healthy cells to radiation | There is no ‘exit dose’, meaning healthy tissue and organs are protected |
| Typical suitability | Helpful for treating prostate cancer, lung cancer and liver cancer, where the tumour can move while breathing | Helpful for treating tumours near sensitive organs, or where sparing healthy tissue is a priority, e.g. in children or previously treated areas |
| Key strength | Real-time motion tracking allows the precise targeting of moving tumours | The radiation can be carefully controlled to stop at the tumour, sparing the surrounding healthy tissues |
When might CyberKnife treatment be more suitable?
CyberKnife treatment may be suitable for treating patients under the following circumstances:
- The tumour is small in size and clearly defined
- The tumour moves when the patient breathes
- Where minimising the number of sessions is important
When might proton beam therapy be more suitable?
Proton beam treatment is typically considered when it’s important to limit radiation exposure to healthy tissues and critical structures.
It may be considered for:
- Larger more extensive tumours
- Treating cancer in children to protect developing tissues and organs
- Treating head and neck tumours to protect the brain, salivary glands, and swallowing muscles
- Treating brain tumours, skull base tumours, or spinal and pelvic tumours near the spinal cord
- When reducing the radiation dose to nearby organs is beneficial to preserve the patient’s quality of life
- Lung tumours close to the heart or other vital structures
- To reduce the risk of long-term side effects and potential secondary cancers
How do I know which treatment option is best for my cancer?
CyberKnife and proton beam therapy are both highly effective treatments, but they are not interchangeable. There is no single best option for everyone.
The most appropriate treatment for you depends on several factors, including:
- your tumour type, size and location
- whether your tumour moves when you breathe
- your treatment history
- your overall health and wider treatment goals
Of course, there are other types of treatment, including traditional radiation therapy, which may be more appropriate for your particular diagnosis. Your radiation oncologist will assess your suitability for treatment based on the criteria above, along with detailed imaging (such as MRI and CT scans). They will then recommend the most appropriate treatment plan, helping you to make an informed decision.
Get advice on private proton beam therapy (PBT)
At Proton International London, we provide proton beam therapy for people across the UK and abroad from our private facility within University College Hospital London (UCLH). If you are considering private PBT, we are here to support you every step of the way.
To ask us a question, please call 0203 9255 885, or start a referral using our contact form. You can also explore our journal to learn more about the cancers we treat, the potential benefits of proton beam therapy, and other insights into advanced cancer care.
Frequently asked questions – CyberKnife vs proton beam therapy for cancer treatment
What is the main difference between CyberKnife therapy and proton therapy?
Both treatments are well established in the field of radiation oncology. The main difference is the type of radiation used and how it is delivered to the tumour.
CyberKnife uses photon radiation (X-rays) with real-time motion tracking, allowing the radiation therapists to target the tumour more precisely.
Proton beam therapy uses protons, which can be controlled to stop at the tumour site, thereby limiting radiation to nearby healthy tissue.
Is Gamma Knife the same as CyberKnife?
Gamma Knife and CyberKnife therapies are both forms of radiation therapy, but they are not the same.
CyberKnife uses X-rays to treat small sized tumours anywhere in the body. It is a non-invasive treatment that uses image-guided robotics to deliver high doses of radiation to tumours with great precision. This makes it particularly useful for tumours that move whilst breathing.
Gamma Knife treatment is used exclusively to treat brain tumours and some upper spinal conditions. It delivers high energy gamma rays using many finely focused beams that converge on the target, guided by detailed imaging. Read more about Gamma Knife therapy and its benefits here.
Which treatment is better for prostate cancer?
There is no single treatment that is better for everyone with prostate cancer. The most appropriate option depends on various factors, including the stage and risk level of the cancer, the size and exact position of the prostate, whether the cancer has spread beyond the prostate, any previous treatments you have had, and your overall health.
Your radiation oncologist will assess all of these factors and discuss the potential benefits and limitations of each type of treatment with you.
