A Brief Overview of Proton Therapy

A Brief Overview of Proton Therapy

A Brief Overview of Proton Therapy

Proton therapy is a form of radiation therapy that uses the positively charged particles called protons. Another name for this form of treatment is proton beam therapy. It is used in the treatment of various types of cancers.

For many years, cancer treatment has depended on conventional radiotherapy with or without the other standard cancer treatment regimens. However, this form of therapy has significant issues that proton therapy has helped to solve.

Proton therapy versus radiotherapy

Conventional radiotherapy uses X-ray beams composed mainly photons (bundle of energy which can either be electromagnetic or light in nature) and electrons. The beam deposits energy along its path as it moves towards the targeted cancer cells. This beam also goes past the intended area. This results in both the healthy and the malignant cells being affected. While the effect is as intended on the cancer cells, the healthy cells are affected negatively and this can lead to serious health issues. Such problems can include secondary cancers in the future.

On the other hand proton therapy works differently. Although this is also a form of radiotherapy, the proton therapy is a highly accurate method compared to standard radiotherapy.  Once a cancerous tumor has been identified, proton treatment can target it with an accuracy that is within a millimeter. The protons beamed to this area is at an energy is that is high enough to destroy the cancer cells. As of now, proton therapy is administered externally. It is painless and only gives the required amount of radiation on the tumor. There is no unintended radiation ‘fallout’ on the surrounding tissues and organs.

What is the technique for proton therapy?

A qualified radiologist who is also conversant with proton therapy treatment leads the procedure. A special machine called a synchrotron is used to ‘fire up’ the protons. The speed of these particles is important because that is what determines how deep the protons can penetrate the body. High speed protons results in high-energy protons and deeper penetration. On the other hand, low-speed protons lead to low-energy level and relatively low-body penetration.

The degree of penetration is important depending on the cancer being treated.  The deeper the cancer is in the body, the higher-energy level is needed to treat it. More superficial cancers require low-energy proton therapy.

Proton therapy works by damaging the DNA of the malignant cells. Since cancer cells usually survive by imbalanced cell multiplication, this damage to DNA essentially stops further multiplication of the cancer cells and therefore the cancer is stopped.

Frequency and duration of proton therapy

This depends on the type of cancer and how far it has spread (stage). Normally, treatment sessions range from 1-5. Some patients may benefit from a single large dose of proton therapy. When this approach is used, it is referred to as radio-surgery. This is a great advantage of this therapy because it enables radiologists to use high radiation doses on the tumor because they know that the surrounding tissues or organs are safe.

A radiologist’s assessment usually leads to an individualized form of proton therapy. It may be given as the sole treatment option or with other forms of cancer therapies may be included.

The treatment duration per session depends on a number of factors such as:

  • Area of treatment

  • Number of areas on the body to receive treatment

  • The number of imaging investigations done during patient positioning

Side effects of Proton Therapy

Although proton therapy uses a highly targeted beam that concentrates on the tumor area, some generalized side effects can still be experienced. This is because cancer cells are living and as they die-off, the body system respond to that giving rise to a number of signs and symptoms. According to some clinics healthy cells may also be affected. This is however, to a very small extent in comparison to conventional radiotherapy. Some of the side effects include:

  • Digestive problems
  • Skin redness on the part the beam enters the body
  • Generalized fatigue
  • Localized hair loss on the part of the treatment on the body
  • Headache
  • Soreness on body part of treatment

The severity of these side effects may be determined by factors such as:

  1. Body part being treatment
  2. Tumor size
  3. Concomitant use of chemotherapy

Types of cancer treated with proton therapy

The accuracy of this method makes it ideal in the treatment of cancers in sensitive areas and those near or in vital organs including the brain, the eye, and the spinal cord. It is also useful in treating childhood cancers owing to its less damage of the surrounding healthy cells. Specific cancers that can benefit from this therapeutic technology include:

  • Eye cancers
  • Brain and spinal cord nervous system cancers
  • Head and neck cancers
  • Liver cancer
  • Prostate cancer
  • Lung cancer

Drawbacks and complications

  1. It may not be ideal for all types of cancer. For example prostate treatment has been seen to be more difficult to manage. However more recent technology such as pencil-beam technology is helping to overcome such proton therapy challenges.
  2. It is still a relatively new treatment method that may not yet have been researched fully.
  3. Very expensive equipment is needed for its administration. This limits the number of centers that can offer the therapy.
  4. It is expensive for the patient and or the insurance company
  5. The degree of accuracy is important. Any slight variation can cause damage to healthy cells


Where to get this treatment

There are relatively few areas that offer proton therapy around the word. As an individual country, the U.S.A has the biggest number of such facilities but there are some other locations such as Italy, Japan, China et and a lot of Medical Center are currently investing in this expensive medical technology.

Cost of Proton Therapy

Proton therapy is apparently more expensive than standard radiotherapy. The synchrotron machine is more expensive than the common x-ray machine. Patient preparation also takes longer and it is more complicated. This adds to the cost of management. According to the National Association for Proton Therapy, insurance reimbursement for this therapy is usually a third higher than that of ordinary radiotherapy.

But when the side effects of conventional radiotherapy are taken into account, the overall treatment with proton therapy could be lower because it has few to no side effects. The patients quality of life is not unduly affected.

Last update 5th of November 2018

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