WHAT IS RADIATION THERAPY?
Radiation therapy is a cancer treatment which targets tumors directly with the aim to kill cancer cells and shrink tumors1 In 70% of all cases, the objective is to cure the cancer by using a precisely calculated dosage of radiation to destroy cancer cells, while preserving as much of the surrounding healthy tissue as possible.2
High-energy radiation beams are used to shrink tumors by stopping cell proliferation and killing cancer cells. X-rays, gamma rays, and charged particles are different kinds of radiation used for this type of cancer treatment.2 For 50% to 60% of patients with cancer, radiotherapy is part of their regular cancer treatment.11 This therapy can be used in combination with surgery and/or chemotherapy.3, 4, 5
HOW DOES RADIATION THERAPY WORK?
Radiation therapy directly damages the DNA of cancer cells with the goal to reduce the cell division rates and induce cell death. This eventually causes the tumor to shrink. A predetermined dose – measured in the international unit Gray (Gy) – will be delivered during the whole radiation treatment. This dose is split into so called fractions in the individual treatment sessions.6
In general, cells are able to repair the damages caused by radiation exposure. However, if the radiation dose is high enough, cells of any kind can be damaged beyond repair. Different cells and tissues in the body tolerate radiation differently, which affects the amount of radiation dosage used depending on the treated body site. Many areas of the body can only tolerate a limited amount of radiation in a lifetime (maximum dosage).7
WHAT IS THE MODE OF ACTION OF RADIATION THERAPY?
As a direct consequence of radiation waves, the DNA of targeted cells is being damaged. When the cancer genes are damaged they cannot grow and divide anymore and over time, the cells die. This means that radiation can be used effectively to kill cancer cells and shrink tumors.7
As an indirect consequence, the water molecules in a cell will not be able to hold the absorbed energy of the radiation beam. The molecules break thus generating high reactive molecules known as free radicals.8 Those free radicals damage the DNA when cells are actively dividing.7
WHAT ARE THE TYPES OF RADIATION THERAPY?
Radiation therapy is a personalized therapy and depends on various factors such as:
- the type tumor
- its location
- the radiation
- treatment duration
- type of therapy.
Different radiation therapy types can be distinguished:
- Internal(brachytherapy) : the source of radiation therapy is placed inside the body, close to the cancer cells.
- External: radiation beams are delivered by a machine outside the body. The beams will go through the skin before reaching the tumor.
- Metabolic radiation therapy: involves a radioactive device, given orally (through drink or capsule) or injected intravenously. Once swallowed or injected the device attaches itself to the cancer cells to destroy them.
WHAT IS SUPERFICIAL RADIATION THERAPY (SRT)?
Superficial Radiation Therapy is a non-invasive, painless, and cosmetically attractive alternative to surgery to fight cancerous cells. This treatment method aims at destroying cancer cells which are located in the skin or the directly underlying tissue. X-rays are used to deliver low doses of radiation (in the range of 50 to 150vKp) to shrink a tumor. This type of therapy avoids deep tissue damage and minimizes scarring, in particular on and around the face. It makes it ideal for the treatment of benign conditions and early stage skin cancer or prevention of a regrowth of a new keloid after surgical removal.6
WHAT IS EXTERNAL RADIATION THERAPY (TELETHERAPY)?
The aim of external radiation therapy is to reach a tumor that cannot be removed by surgery, but one that is suitably located not to use chemotherapy. Radiation therapy is a personalized therapy and depends on the type and the location of a tumor. A patient will always receive a unique treatment. Before starting an external radiation session, the patient will undergo a simulation to determine the best way to reach the tumor and save surrounding tissues at the same time. Doctors will also calculate the total radiation dose and number of sessions.8
At the beginning of each radiation session, the patient is positioned and the radiation machine starts to move around them whilst emitting radiation beams. One session only lasts a few minutes.
Each beam will pass through the skin before reaching the tumor. The goal is to deliver a maximum of radiations to the tumor. This will kill the cancer cells thus cause the tumor to shrink. During or after a session, the patient does not emit any radiation. Depending on countries and protocols, the treatment schedule varies from a few days up to a few weeks.9
WHAT IS INTERNAL RADIATION THERAPY (BRACHYTHERAPY)?
Radiation is given through radioactive materials (normally isotopes) that are inserted into the body and are placed in close contact with the tumor. The radiation dosage can be modulated depending on the inserted device. Patients may emit radiation at low doses and special behavioral instructions are given to monitor contact with children and infants.
The most common brachytherapy types are:
- Interstitial implant: in the tumor or in direct contact with the tumor
- Temporary implant: skin, breast or sarcomas
- Permanent implant: prostate
WHAT IS METABOLIC RADIATION THERAPY (SYSTEMIC RADIATION THERAPY)?
The aim of this therapy is to target small sized tumors which are spread throughout the body. Radioactive drugs (injected or swallowed) with special biological properties will be used to selectively target the tumor cells.
Iodine 131 is an example of a substance which is used to treat thyroid cancer. It will naturally attach itself to the thyroid gland and eventually kill the cancer cells.10
WHAT IS THE PROCESS OF A COMMON TREATMENT PROCEDURE?
A linear accelerator will direct high energy radiation beams into the patient’s body. The patient is situated on a table while the linear accelerator moves around them to deliver radiation from several angles. During the treatment, the machine emits a “buzzing” sound. Every treatment session only last a few minutes.11
The patient might be positioned with the help of molds to hold them in place. The linear accelerator can be adjusted to every patient’s individual needs to deliver the precisely calculated radiation dose.11
The radiation therapy team stays in a room nearby with a video and audio connection to monitor the patient during the session. The patient can notify the staff if they feel uncomfortable, but normally they should not experience any pain during a radiation therapy session.11
Typically, external beam radiation sessions are scheduled every weekday over a certain period of time (weeks). The patient can go home after each session. In most cases, treatments are usually spread out over several weeks to allow the healthy cells to recover in between radiation therapy sessions.11
A whole therapy session usually lasts over an hour, since the radiation team will need to adjust the machine and assure that the patient is in the correct position. The actual duration of a radiation treatment is only a few minutes.11
WHAT ARE THE TYPES OF LINEAR ACCELERATOR (LINAC)?
- Three-Dimensional Conformal RT (3DCRT)
- Intensity Modulated RT (IMRT)
- Image-guided RT (IGRT)
- The Gamma Knife and Cyberknife
- Proton therapy
WHAT SKIN REACTIONS CAN OCCUR?
- Redness – the skin in the treatment area may resemble a mild to severe sunburn or tan.
- Pruritus – itchiness is a normal side effect in the treated area. Scratching can compromise skin integrity.
- Inflammation – swelling, pain and heat might occur in the treatment area.
- Dry desquamation – the skin in the treatment area may become thicker and very dry. In most cases, the skin peels off similar to what occurs after sunburns.
- Moist desquamation – skin cells are destroyed faster than they can grow back. The skin may break down, become wet or infected. This is more common where the skin is very thin or folds such as behind ears, under breasts or neck.
WHICH ARE THE FIRST SYMPTOMS 10-15 DAYS AFTES THE FIRST RADIATION THERAPY DOSE?
In general, radiation skin damage can be seen approximately 10–14 days after the first dose of radiation. This corresponds with the time it takes for impaired cells to migrate to the surface of the skin. If the new cells reproduce faster than the old cells are shed, the skin will become dry and flakey (dry desquamation).
When radiotherapy continues, the body may not produce enough new cells to replace the old ones. As a result, the outer layer of the skin may break and start to ooze – so called moist desquamation has developed.
The severity of skin reactions may increase for 2 more weeks after the completion of radiation therapy. Each hospital has a different way of managing radiation dermatitis, based on the skin’s condition.
WHAT IS THE TREATMENT OF RADATION DERMATITIS?
During radiation therapy not only cancer cells are destroyed, but also nearby existing healthy cells are also affected by this form of treatment. Additionally, a patient may develop unpleasant and sometimes serious side effects, such as radiation dermatitis. The prevention and treatment of these side effects are an essential part of the whole treatment protocol, because it can have an extensive impact on the treatment outcome.
The best way to manage radiation dermatitis is to prevent it. It is of high importance to use products which help to preserve the fragile epidermis for longer while providing symptomatic relief at the same time.
Recommendations for radiation dermatitis:
- Wear loose clothing.
- Avoid direct sunlight and use sunscreen.
- Use non-perfumed, mild soap.
- Gently pat your skin dry after showers or baths.
- Avoid swimming in chlorinated water as it can have a drying effect on the skin
- Do not rub off the markings your radiation therapist made on your skin. They show where to place the radiation beams.
- Do not put anything that is very hot or cold on the radiated area.
- Use an electric razor if you are allowed to shave.
- Do not “wet-shave” or use hair removal products.
- Porock D, Kristjanson L. Skin reactions during radiotherapy for breast cancer: the use and impact of topical agents and dressings. Eur J Cancer Care. 1999 Sep;8(3):143-53.
- McGregor S, Minni J, Herold D. Superficial Radiation Therapy for the Treatment of Nonmelanoma Skin Cancers. The Journal of Clinical and Aesthetic Dermatology. 2015;8(12):12-14.
- McQuestion. Seminars in Oncology nursing 2006;22(3):163–173
- The National Cancer Institute (NCI), (2018). Common Terminology Criteria for Adverse Events (CTCAE). Retrieved 3 April 2018, from https://ctep.cancer.gov/protocolDevelopment/electronic_applications/ctc.htm
- The Princess Royal Radiotherapy Review Team, St James’s Institute of Oncology, The Leeds Teaching Hospitals NHS Trust. Taken from the publication “Managing Radiotherapy Induced Skin Reactions, a Toolkit for Healthcare Professionals”. Retrieved 7 March 2018, https://www.sor.org/system/files/news_story/201204/ltht-managingradiotherapyinducedskinreactions-oct2011.pdf
- Noble-Adams R. Radiation-induced reactions 2: development of a measurement tool. British Journal of Nursing 1999b;8(18):1208–1211
- Lopez E, Nunez MI, Guerrero MR, del Moral R, de Dios Luna J, del Mar Rodriguez M, et al. Breast cancer acute radiotherapy morbidity evaluated by different scoring systems. Breast Cancer Res Treat.2002 May;73(2):127-34.
- Kedge. Radiography 2009;15:247–257
- American Cancer Society, Inc.(2018) External Beam Radiation Therapy. Retrieved 7 March 2018, from https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/radiation/external-beam-radiation-therapy.html
- Trueman E. The Princess Royal Radiotherapy Review Team. 2011.
- Noble-Adams R. Radiation-induced reactions 1: an examination of the phenomenon. British Journal of Nursing 1999a;8(17):1134–1140