Radiotherapy: Information and radiotherapy specialists

Radiotherapy (also known as radiation therapy or simply radiation treatment) is frequently used in the treatment of cancer, alongside surgery and chemotherapy. 

One in two cancer patients undergoes radiotherapy at some stage during the course of their illness. Chemotherapy, which involves medication (‘systemic’ chemotherapy), affects the whole body. Radiotherapy, on the other hand, is a purely localised treatment. The effect of the radiation is therefore only felt where the beams are directed – that is, within the treatment field.

Radiotherapy can

• be used in combination with chemotherapy (radiochemotherapy) and
• be used, in consultation with the treating surgeon, after (adjuvant) or before (neoadjuvant) surgery

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For some types of cancer, such as localised laryngeal cancer or prostate cancer, radiotherapy is the only possible treatment. Radiation therapy is also one of the standard treatments for prostate tumours. 

Furthermore, radiotherapy can be used as part of cancer treatment to alleviate or prevent symptoms. 

Malignant tumours are very frequently treated with radiotherapy, often in combination with other treatments such as surgery and chemotherapy. Around one in two cancer patients undergoes one or more courses of radiotherapy.

Depending on the purpose of the radiotherapy, a distinction is made between

• curative radiotherapy: the aim is to cure the patient and completely remove the cancer cells.
• palliative radiotherapy: if a cure is no longer possible, radiotherapy can alleviate symptoms and improve the patient’s quality of life.
• neoadjuvant radiotherapy: the aim is to shrink the tumour before surgery, thereby improving the chances of a successful operation.
• adjuvant radiotherapy: Adjuvant radiotherapy is intended to consolidate the results of a previous operation and destroy microscopically small tumour foci.

Cancer treatment always follows the principle of ‘logarithmic cell killing’. Tumours often consist of 100 billion individual cells. When aimed at a cure, radiotherapy is designed to destroy the tumour right down to the very last cell.

As individual tumour cells can no longer be detected, the true success of the treatment only becomes apparent after months or years.

If the tumour reoccurs at the same site during the observation period, a recurrence is assumed.

In radiotherapy, cancer cells are destroyed by ionising radiation or particle radiation.

Radiotherapy and the destruction of genetic material

The radiation damages the genetic material of cells, causing cell division to stop and the cells to die. The tumours shrink or even disappear.

The cell-damaging effects of radiotherapy are non-specific. Healthy cells are also affected. However, depending on the extent of the damage, the cells’ own repair systems can repair damage to the genetic material. Like a pair of scissors, they cut out sections of the DNA and replace them.

This ability to regenerate genetic material is more pronounced in healthy cells than in cancerous ones. Whilst healthy cells normally regenerate, cancer cells die off and are removed by the body’s own immune cells.

However, healthy cells require sufficient time to repair the damage to their genetic material. For this reason, in radiotherapy, the total radiation dose to be received by the patient must be divided into several individual sessions (fractions).

The doctor selects the radiation dose based on the tumour’s sensitivity to radiation. If a cure is required, the radiation dose ranges from 40 to 70 Gray (Gy). The total dose required to destroy the tumour is divided into fractions of 1.8 to 2 Gy each (standard fractionation). This ensures good tolerability and reduces the risk of irreversible damage and late complications.

However, the ability of healthy tissue to heal remains the limiting factor for curative radiotherapy.

Targeted irradiation of cancer cells

New precision radiotherapy techniques, such as intensity-modulated radiotherapy (IMRT), enable the precise targeting of tumour tissue. This means that less healthy tissue is affected during radiotherapy. Such techniques make so-called hypofractionated radiotherapy possible. In this approach, the required radiation dose is administered in several fractions. Less attention needs to be paid to the recovery of healthy tissue.

In most cases, radiotherapy is administered as ‘external’ radiotherapy. This means that the radiation is generated by a specialised radiotherapy machine and directed through the skin to the tumour inside the body. In particularly complex cases, a stereotactic radiotherapy technique is used, which targets the tumour with pinpoint accuracy from several angles.

These devices, which generate radiation, are called linear accelerators. A linear accelerator accelerates electrons to almost the speed of light. The electrons escaping from the accelerator can then be used directly to treat superficial tumours.

However, when treating deeper-seated tumours, the energy of the electrons is first converted into X-rays (photons) through a physical process. X-rays have a greater penetration depth in tissue than electron radiation.

Typically, the penetration depth of a type of radiation increases with increasing energy.

The side effects of radiotherapy depend heavily on the dose of radiation energy administered, which increases steadily over the course of treatment. Consequently, side effects may sometimes not peak until 7–10 days after the end of treatment. They then gradually subside.

It is important to continue with the prescribed aftercare until the side effects have disappeared. Most side effects should have subsided within 4 weeks. This timeframe may vary depending on your personal sensitivity, the area exposed and the energy dose.

In some cases, the skin may

• become dry,
• flaky and
• red

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Sometimes, the exposed skin may also develop a tan (pigmentation). Skin that has been exposed to radiation is sensitive to mechanical irritants. You should therefore look after your skin from the very first exposure to radiation until three weeks after the end of treatment: avoid anything that irritates the skin and, above all, causes stress.

Thanks to technological advances, severe skin reactions are much rarer today than they used to be. Any skin reactions may persist for some time after the end of treatment and may sometimes temporarily worsen.

In the first few months following exposure, your skin will be more sensitive to light and the sun. Ensure that you have adequate protection against the sun and cold wind for the first 12 months after exposure.

Similarly, the other side effects of the treatment should disappear within a few weeks of treatment ending. Depending on your specific situation, you will receive detailed information on this at the end of your treatment.

Patients often complain of drowsiness or tiredness following cancer treatment. Some patients take longer to recover. Try to eat as normal. Light exercise or moderate physical activity will aid your recovery.

Like any other treatment, radiotherapy can have potential side effects. Symptoms that may occur during or after radiotherapy depend on various factors. These include, for example, whether you have already had surgery or received chemotherapy.

The type and extent of the radiotherapy also play a role. As with surgery, the following applies here too: the more extensive the radiotherapy – that is, the more widespread the disease – the more symptoms you may experience.

Before and during treatment, your doctor will discuss in detail with you what you can do yourself to minimise acute side effects during radiotherapy.