Radiotherapy (radiation therapy)

Radiotherapy is an important pillar of treatment for cancer. It helps with a wide variety of cancers. High-energy radiation is used, which can be directed specifically at the malignant tumor. The cancer cells are damaged and die. Read about exactly how radiation therapy works, what types are available, and how it works. Plus: The most important tips for preparing for radiotherapy as well as aftercare.

Overview: What is radiotherapy?

Radiotherapy (radiation therapy) is a very important treatment option for people with cancer – along with surgery, chemotherapy, targeted drugs, immunotherapy and hormone therapy. It is used for many different types of cancer, for example breast cancer, colorectal cancer or prostate cancer. Radio-oncologists use high-energy radiation to combat malignant tumors. These beams are generated by a special device, usually a linear accelerator.

Cancer cells are more sensitive to radiation than healthy cells because they divide and multiply faster. The rays damage the genetic material (DNA) of the cancer cells. Unlike healthy cells, however, the malignant tumor cells can no longer repair this damage. They can no longer divide and die. The aim is to eliminate all cancer cells with the help of radiation, or to slow down the growth of a tumor.

Radiotherapy is a treatment that acts mainly on site (locally) and is very precise. It is effective only at those sites where the radiation actually hits – i.e. in the area of the tumor itself or, for example after an operation, in the former tumor bed. In contrast, chemotherapy exerts its effect throughout the body (systemically). During irradiation, healthy tissue should be spared as much as possible. However, there are also healthy, rapidly dividing cells that can be affected by irradiation. Examples are the skin and mucosal cells. Therefore, reactions to the skin and mucous membranes are common side effects of this cancer therapy.

There are different types and applications of radiotherapy:

  • For most cancers, radiation enters the body from the outside through the skin (percutaneous radiation therapy).
  • In addition, there is radiation from the inside (brachytherapy), for example in the case of cervical cancer. In this procedure, a radiation source is introduced directly into the tumor and can thus act from the inside.
  • Stereotactic radiotherapy is a high-precision radiation treatment. It is suitable for small tumors located deeper in the tissue. It can be compared to a “surgical knife made of rays”. Therefore, the method is also called radiosurgery.

Experts also distinguish whether radiation is curative with the goal of cure or palliative. In the latter case, radiation is aimed at slowing the progression of the tumor, halting its growth, or relieving discomfort, for example due to metastases in the bones.

Radiation therapy can be used as a stand-alone therapy, or it can be used in combination with chemotherapy, targeted medications, immunotherapies and hormonal therapies.

Radiation therapy can also be used adjuvantly as a support after surgery and chemotherapy to eliminate any remaining cancer cells. It can be used neoadjuvantly to shrink the tumor before surgery. Then it can be better operated in selected cases.

Radiotherapy procedure

Be well informed beforehand about the radiation therapy procedure and the possible side effects and late effects. Then you know what you might be up against. Radiation therapy may have some side effects, such as:

  • Tiredness, exhaustion up to fatigue
  • Skin reactions, e.g. reddening of the skin, inflammation
  • Feeding problems, such as when the esophagus or oral pharynx is irradiated
  • Gastrointestinal problems when irradiated in the area of the gastrointestinal tract
  • Hair loss
  • Damage to the teeth
  • Impairments of fertility

The side effects always depend on which part of the body is irradiated, how far the cancer has spread and which dose is chosen.

The radiation dose is usually not administered all at once in one session, but divided into smaller “portions.” Therefore, you need to go to radiation every day during the week. The duration of treatment can vary and can be several weeks – depending on the type of cancer and the extent of the cancer.

You can usually undergo radiotherapy on an outpatient basis. So you only come to the clinic for radiation and can go home afterwards. Inpatient radiotherapy, where you stay in the hospital, is only necessary in a few cases. Always discuss this with your treating physicians.

The course of radiation therapy (from the outside) can be described like this:

  • Radiation therapy requires precise planning in advance (see the “Preparation” section below).
  • For the radiotherapy itself, you will take a seat on an irradiation table. It is a component of the irradiation device and can be moved into different positions. The specialist personnel place them so that the rays hit your tumor exactly. At each session you need to take the same position.
  • Before each therapy session, the specialist staff checks the settings on the irradiation unit. Control images also show whether the bearing is correct.
  • During the session, you must lie as still and as relaxed as possible.
  • You are alone room during irradiation. However, you are connected to the radiology staff in the next room via an intercom system and video camera.
  • The linear accelerator travels around you from a precisely defined direction and at specific intervals.
  • The radiotherapy itself lasts only a few minutes. So one session is quickly done.
  • By the way, after radiation therapy you are not a radioactive danger to others – you can have normal contact with other people.

Preparation: Radiation therapy needs to be well planned

Radiotherapy needs one thing above all: good planning, because it is real custom work for the treatment team. The aim is to irradiate the tumor with the highest possible doses while sparing healthy tissue sufficiently. You yourself will also have to be a little patient until all the settings and the position are right. Experts from various disciplines are involved in the planning, such as specialists from radio-oncology and physics as well as specialists in medical-technical radiology (MTRA).

The main steps are:

  • Specialists use computed tomography (CT) to plan radiotherapy. They read the images into a radiation planning computer. In this way, the area of the body to be irradiated can be determined to the millimeter.
  • The treatment team then creates a 3-D image and determines the arrangement of the radiation fields that is most favorable in each case. With the help of radiation planning on the computer, it is possible to calculate in advance which radiation dose will hit which part of the body.
  • Sometimes it may be necessary for specialists to make marks with a waterproof pen on the areas on the body that are to be irradiated. These marks are taped off and remain there throughout radiotherapy. You must not wash them off.

Radio-oncologists calculate the total dose with which you should be irradiated. The unit for this is “Gray” (Gy). They divide them among several meetings(individual fractions). Thus, the dose is usually not administered all at once.

The schedule for radiation therapy may vary – depending on the type of cancer. You usually have to go to radiation therapy five times a week, with breaks on the weekends. How many weeks you should expect also depends on your individual cancer. Two radiation sessions per day (hyperfractionated) or only one to three radiation sessions per week (hypofractionated) are also possible. Always discuss your personal schedule well with your treating health care providers.

Before radiotherapy: tips

For the time before the radiation treatments, the following tips may be helpful:

  • Clarify the arrival and departure in advance. In most cases, the arrival and departure can be easily managed by public transport or even by car. There are also appropriate driving services if you do not want to drive yourself and no relative or friend has time. For short distances, perhaps a walk or bike ride is a good option – exercise is good for your health.
  • If you are not physically fit due to the strenuous cancer therapies – find out if you can get household help to support you.
  • Normally, you can eat and drink normally before radiation. An empty stomach is usually not necessary. However, there are exceptions, for example, irradiation of the stomach and intestines. Discuss this issue with your treatment team in advance.
  • Wear clothes that are comfortable and that you can take off quickly. Then you do not waste too much time in the locker room.
  • Ask your treatment team if you can use cosmetics such as creams, ointments, powders, deodorants, makeup, or perfume before radiation. Body care products that you use outside the irradiation fields are usually not a problem.

Aftercare: Tips for the time after radiotherapy

Immediately after radiation, you may find these tips helpful:

  • Skin care: Irradiated skin needs special care. Have your treatment team recommend products that are gentle on the skin – the point is to avoid further irritating the skin. Some tips: Wash skin only with lukewarm water or pH-neutral soap; use skin-friendly products; do not rub skin dry, but dab gently with soft towel.
  • Make sure you have adequate sun protection – do not expose the irradiated areas to direct sunlight.
  • Do not scratch if your skin itches – it can become inflamed.
  • It is best to wear loose clothing made of natural materials rather than synthetics, such as linen, cotton or silk. You sweat less in it. Also, avoid scratchy and abrasive clothes that stress the skin.
  • Move around as much as possible. Go for a walk, ride a bike or take a short hike. But do not overexert yourself!
  • Make sure you have enough relaxation
  • Eat a healthy, balanced and varied diet and don’t forget to drink (e.g. tea, water, fruit juice spritzers – at least 1.5 liters per day).
  • Do not smoke and it is best to avoid alcohol, because you put additional strain on your body. If this is not possible for you, the following applies: Keep it moderate!

Aftercare after radiotherapy

Follow-up care is an important component of any cancer therapy. Doctors check the success of radiotherapy, look for signs of relapse (recurrence), and ask you about symptoms, possible side effects, and long-term effects of radiotherapy. For example, some struggle with skin problems after radiotherapy, others with chronic fatigue. Depending on the type of cancer, radiotherapy can cause various side effects and late effects. However, the complaints can often be treated well.

Part of the follow-up care also includes a physical examination, blood tests and imaging procedures such as computer tomography (CT) and magnetic resonance imaging (MRI = magnetic resonance imaging).

Follow-up after radiotherapy is performed at specific time intervals. Initially, the intervals are shorter, later they extend further and further if no relapse is apparent. Follow-up care can be provided by clinics such as the University Hospital Zurich (USZ) or by specialized oncology practices. The primary care physician’s office or other specialty practices can also be involved in follow-up care as needed.


Radiotherapy is usually performed in a radiooncology department in a hospital or in an appropriate specialized practice. There are the appropriate devices and the specialized personnel who have a lot of experience with irradiation.

Gather all documentation and findings before going to radiation. These include the pathological findings, which contain the characteristics of your cancer as a kind of “fingerprint”, but above all the results of imaging procedures. The images are also important for planning radiotherapy.

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