Radiation therapy for cancer — how does it work?

Most people associate radiotherapy with the treatment of cancer, but it is also used in the treatment of other, non-cancerous conditions. In the case of cancer, it is, next to chemotherapy and surgery, the most frequently used method of oncological treatment. How does radiation therapy work? What does it look like, and what are the side effects?

What is radiotherapy?

Oncological radiation therapy uses the properties of ionizing radiation to affect cancer cells. This effect, depending on the type of neoplasm and its stage of development, may include their destruction, growth inhibition or reduction of symptoms (e.g. cancer pain). Radiotherapy is especially effective in the treatment of primary tumors as well as lymph node metastases. This method is used both as a standalone treatment and as part of a combination treatment (e.g. with chemotherapy).

This method is based on the negative effects of radiation on cells. Ionizing radiation used in radiotherapy creates free radicals, i.e., unpaired atoms, in a treated tissue. Cells in irradiated tissues change in structure and function. Moreover, radiation toxins that appear during radiation treatment can destroy the proteins of cancer cells. As a result, tumor mass can be reduced.

How is the radiation dose selected?

Before radiotherapy is introduced into the treatment plan, it is necessary to analyze the results of the various tests. It’s provided by a doctor on the basis of the following diagnostic tests:

• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET)

On their basis, it’s determined which area of the body will be threatened with radiation. It can involve both the tumor itself and adjacent lymph nodes. The next step is to choose the treatment method and amount of radiation. These medical arrangements are performed by medical physicists. Thanks to appropriate treatment tailored to the patient, it guarantees that the radiation is directed to the right area and the highest possible protection of other organs.

What does radiation therapy look like?

Once the treatment strategy has been established, the first step — before the proper exposure to radiation — is to run a simulation. It consists in marking the area on the body that will later be treated by radiation. It’s also the time when medical staff determine areas that should be shielded from radiation. During this step, to mark those areas, doctors mark dots (centering points) on a patient's body with a special ink. Those marks are like a tattoo, so they can serve as navigation points for the emitted radiation beam throughout all treatment.

In earlier years, for radiation therapy X-ray radiation, as well as chemical elements such as radium and cobalt, was used. Currently, the radiation is generated by the so-called linear accelerators. Modern methods help to minimize side effects of radiation therapy.

How long does radiation therapy last?

The duration of radiotherapy depends primarily on the type of cancer and its stage. Based on this information, the doctor determines the appropriate therapeutic dose. Treatment may last from one to several weeks. There are also one-time therapies. The session itself, during which the patient is exposed to radiation, lasts from a few to several minutes. In order to reduce the negative impact of radiation on healthy cells, the total dose of radiation is administered in multiple sessions. In the breaks between them, the body has time to regenerate — healthy cells are renewed and damage is repaired. Cancer cells do not have this ability — they are not able to regenerate as efficiently as healthy cells — so they die during subsequent doses.

What are the side effects of radiation therapy?

The side effects of radiotherapy mainly affect skin, which quickly becomes dry and prone to chafing, and peels off just after a few sessions. Even after just one session, skin can become very sensitive in the treated area. It also causes pressure sores in patients who have to lie in bed for a long time. Radiotherapy requires special care of the skin. Skin care after radiation therapy should include using products that will allow it to regenerate and that will provide additional protection. By following these guidelines, side effects of radiation therapy can be largely avoided or reduced.