Radiotherapy (also known as radiation therapy or simply irradiation) is often used in cancer treatment alongside surgery and chemotherapy.
Radiotherapy is used in every second cancer patient during the course of the disease. Drug-based ("systemic") chemotherapy affects the entire body. Radiotherapy, on the other hand, is a purely local measure. The effect of the radiation is therefore only seen where the radiation is used, i.e. in the radiation field.
Radiotherapy can be used
be used.
For some types of cancer, such as localized laryngeal cancer or prostate cancer, radiotherapy is the only possible therapy.
Radiotherapy can also be used in cancer treatments to alleviate or prevent symptoms.
Very often, malignant tumors are treated with radiotherapy, often in combination with other treatments such as surgery and chemotherapy. Around every second cancer patient undergoes one or more radiotherapy treatments.
Depending on the purpose of radiotherapy, a distinction is made between
Cancer treatment always follows the law of "logarithmic cell killing". Tumors often consist of 100 billion individual cells. Radiation therapy is designed to destroy the tumor down to the last cell for the purpose of healing.
As individual tumor cells can no longer be detected, the actual success of the treatment only becomes apparent after months or years.
If the tumor develops again at the same site during the observation period, a recurrence can be assumed.
A linear accelerator irradiates targeted tumors © Maksym Povozniuk | AdobeStock
In radiotherapy, cancer cells are destroyed by ionizing radiation or particle radiation.
The radiation damages the genetic material of cells so that cell division stops and cells die. The tumors shrink or even disappear.
The cell-damaging effects of radiotherapy are non-specific. Healthy cells are also affected. However, depending on the degree of damage, the cell's own repair systems can repair damage to the genetic material. Like a pair of scissors, they cut sections of DNA and replace them.
This ability to regenerate genetic material is more pronounced in healthy cells than in cancerous ones. While healthy cells normally regenerate, cancer cells die and are removed by the body's own immune cells.
Healthy cells, however, need enough time to repair the damage to their genetic material. For this reason, the total radiation dose to be received by the patient during radiotherapy must be divided into several individual sessions (fractions).
The doctor selects the radiation dose based on the radiation sensitivity of the tumor. If a cure is necessary, the radiation dose ranges from 40 to 70 Gray (Gy). The total dose required to destroy the tumor is divided into fractions of 1.8 to 2 Gy each (normal 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.
New precision radiation techniques enable the precise localization of tumour tissue. This means that less healthy tissue is affected by the radiation. Hypofractionated radiation is possible with the help of such methods. The required radiation dose is administered in several fractions. Less attention should be paid to restoring healthy tissue.
In most cases, radiation is administered "from the outside". This means that the radiation is generated with a special radiation device and directed through the skin ("percutaneously") to the tumor in the body.
These devices that generate radiation are called linear accelerators. With a linear accelerator, electrons are accelerated to almost the speed of light. The electrons escaping from the accelerator can then be used directly to treat surface tumors.
When treating deeper tumors, however, the energy of the electrons is first converted into X-rays (photons) through a physical process. X-rays have a greater range in tissue than electron radiation.
Typically, the penetration depth of a type of radiation increases with increasing energy.
The dose of radiation energy administered increases steadily over the course of treatment. Therefore, side effects can sometimes only reach a maximum 7-10 days after the end of therapy. After that, they gradually subside.
It is important to continue with the prescribed care until the side effects disappear. Most side effects should subside within 4 weeks. This time interval may vary depending on your personal sensitivity, the area of exposure and the absorbed dose.
In some cases, the skin may
red.
Sometimes the exposed skin tissue can also develop a tan (pigmentation). Irradiated skin is sensitive to mechanical irritants. You should therefore take care of your skin from the first exposure to radiation until three weeks after the end of treatment: Avoid anything that irritates and, above all, causes stress.
Due to technical progress, severe skin reactions are much rarer today than in the past. Any skin reactions may persist for some time after the end of treatment and may sometimes temporarily worsen.
In the first few months after exposure, the skin is more sensitive to light and sunlight. Make sure that you have good protection from the sun and cold wind for the first 12 months after exposure.
After radiotherapy, the skin must be protected from possible environmental influences © matusciac | AdobeStock
The other side effects of the therapy should also disappear within a few weeks of the end of treatment. Depending on your specific situation, you will receive specific information on this at the end of the therapy.
Patients often complain of drowsiness or fatigue after tumor treatment. Some patients need longer to recover. Try to eat normally. Light exercise or moderate sporting activity will support your recovery.
Like any other treatment, radiotherapy can have 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 chemotherapy.
The type and extent of radiotherapy also play a role. As with surgery, the same applies here: The more extensive the radiotherapy, i.e. the more extensive the disease, the more symptoms may occur.
Before and during treatment, your doctor will discuss with you in detail what you can do yourself to minimize side effects during radiotherapy.
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