What is proton therapy?

Proton therapy is a radiation technique that the UMCG has been offering since 2018. Currently, more than half of all cancer patients require radiation therapy. The goal of radiation therapy is to kill cancer cells while sparing healthy tissue as much as possible.

In the Netherlands, radiation treatment for cancer patients almost all patients are treated with photon therapy. Photons are invisible rays, electromagnetic waves, which are also used to create X-rays. Photons deliver their dose to the area being treated (the tumor), but also deliver a dose to surrounding healthy tissue. Protons, on the other hand, deliver their dose more accurately. Compared to photons, treatment with protons results in a lower radiation dose to surrounding healthy tissue, while maintaining the same dose to the tumor. This reduction in dose to healthy tissue can result in a reduction in side effects. Proton therapy provides a solution for patients with tumors close to vulnerable organs or for patients whose tumors are relatively insensitive to conventional radiation.

Download infographic 'Photon and Proton Therapy' (Dutch)

How does proton therapy work?

Proton therapy is a form of radiation therapy that uses high-dose, precise radiation with protons to target tumors in the body. Protons are small, positively charged particles that release most of their energy after entering the tumor. One characteristic of protons is that they can penetrate to a certain depth in the body before losing their energy. This means that protons primarily do their work in the tumor itself, and affect the surrounding tissue much less, allowing that tissue to remain better preserved. This results in a lower risk of damage to healthy tissue and surrounding organs, reducing the risk of side effects.

Proton therapy in the Netherlands

Proton therapy is a therapy recognized by the Dutch government. Until 2017, patients could only go to treatment centers abroad if they were eligible for proton therapy. To be able to offer the therapy in the Netherlands, a special WBMV (Special Medical Procedures Act) permit is required. The UMCG Proton Therapy Center has this permit and opened its doors in January 2018 as the first proton therapy center in the Netherlands.


What are the benefits of proton therapy?

The risk of side effects after proton therapy is lower than after conventional photon radiation therapy. This applies to a part of the patients being treated. This results in better daily functioning and quality of life for the patient. The risk of side effects depends on where the tumor is located, as well as the type of cancer being treated. Therefore, proton therapy does not provide the same benefits for every patient.

Early and Late Side Effects

When tumors are treated with radiation, it is inevitable that healthy tissue will also be exposed to radiation, which can cause side effects.

  • Early side effects can occur during or shortly after the treatment. The nature of the side effects depends on the area being irradiated. For example, skin irritation only occurs in the area being irradiated. Swallowing problems only occur if the mouth, throat or esophagus is in the radiation area. Diarrhea can occur if a part of the intestine is in the radiation area. Early side effects usually gradually decrease after the radiation treatment is completed. This can take several days to several weeks.

  • In addition to early side effects (which usually resolve), late side effects can also occur. Some symptoms that arise during radiation treatment do not go away, and can even worsen over long term. For example, a dry mouth after radiation treatment of the mouth or throat. Late side effects can sometimes occur years after treatment. For example, a heart attack after radiation for breast cancer.

In all cases, the risk of side effects increases as the amount of healthy tissue that is exposed to radiation during treatment increases. For some patients, proton therapy can reduce the amount of healthy tissue that is irradiated, thereby reducing the risk of these early and late side effects.

Download the infographic ‘Difference between Photon and Proton Therapy’ (in Dutch)

Who is eligible for proton therapy?

Patients are only eligible for proton therapy if they are undergoing a curative treatment. Indications for proton therapy are divided into categories in the Netherlands, including “standard indications” and “model-based indications.”

Standard indications

Standard indications are accepted indications for proton therapy. For these indications, in principle, all patients can be referred for proton therapy and the treatment is covered by the (Dutch) health insurance. We treat the following standard indications:

  • Tumors in children (the UMCG Proton Therapy Center is the only center in the Netherlands where children can be treated with proton therapy);
  • Skull base tumors;
  • Brain tumors with a favorable prognosis without the possibility of high-precision radiation therapy (stereotactic radiotherapy) (approximately 5-10% are eligible for proton therapy);
  • Brain tumors where both the brain and the entire spinal cord need to be irradiated (the UMCG Proton Therapy Center is the only center in the Netherlands where the craniospinal axis can be treated with proton therapy);
  • Testicular cancer / seminomas in patients younger than 50 years old.

Model-based Indications

Patients with so-called model-based indications do not automatically qualify for proton therapy. Treatment with protons is only possible after a positive planning comparison. The comparison must demonstrate (for the individual patient) a clear reduction in damage to healthy tissue and a significantly lower risk of complications with proton therapy instead of photon therapy. At present, it is possible to apply for a planning comparison for the following model-based indications:

  • Breast cancer (about 5% of the patients qualify for treatment with protons)
  • Head and neck tumors (about 50% of the patients qualify for treatment with protons)
  • Lung cancer and other tumors in or near the lungs (about 30% of the patients qualify for treatment with protons)
  • Esophageal cancer (about 70% of the patients qualify for treatment with protons)
  • Lymphoma in the chest (about 50% of the patients qualify for treatment with protons)


protonentherapie bij tumoren in de borstholte

What is a planning comparison?

To make it clear whether proton therapy offers significant benefits, for model-based indications a planning comparison must always be made. The planning comparison compares the photon plan of the referring center with a proton therapy plan made by us. Based on the planning comparison, the difference in the risk of side effects can be calculated. If this difference meets the criteria of the National Indication Protocol for Proton Therapy, the patient is eligible for treatment with proton therapy. Only when the planning comparison shows that proton therapy is the best treatment option, the (Dutch) health insurance company will cover the treatment. Your treating specialist can request a planning comparison. You can always ask your specialist for information about proton therapy and the possibility of a referral.

planningsvergelijking umcg protonentherapie

Zie ook

Uw behandelteam

Het UMCG Protonentherapiecentrum is een onderdeel van het Comprehensive Cancer Center van het UMC Groningen.

Uw behandelend arts bij het UMCG Protonentherapiecentrum is een radiotherapeut-oncoloog, een medisch specialist op het gebied van behandeling van kanker met protonenbestraling. Benieuwd naar uw behandelteam? We stellen ons graag aan u voor.