What Is Radiotherapy? What Is Radiation Therapy?

Radiotherapy is also known as radiation therapy, radiation oncology and XRT. It is used for treating cancer, thyroid disorders and some blood disorders. Approximately 40% of cancer patients undergo some kind of radiotherapy. It involves the use of beams of high-energy X-rays or particles (radiation) to destroy cancer cells. Radiotherapy works by damaging the DNA inside the tumor cells, destroying their ability to reproduce.


According to Medilexicon's medical dictionary, radiation oncology is "1. the medical specialty concerned with the use of ionizing radiation in the treatment of disease; 2. the medical specialty of radiation therapy; 3. the use of radiation in the treatment of neoplasms (tumors).
Radiotherapy can be used for different reasons

Total cure



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What is radiation?


What is cancer? What causes cancer?


What is chemotherapy? What are the side effects of chemotherapy?


What is skin cancer? What is melanoma?


What is anal cancer? What causes anal cancer?


What is colorectal cancer? What causes colorectal cancer?


What is colon cancer? What causes colon cancer?


What is lymphoma? Lymphoma causes and treatments.


What is leukemia? What causes leukemia?


What is breast cancer?


What is function of the lymph nodes?

To cure the patient by completely destroying the tumor.

To alleviate symptoms


Radiotherapy is often used to relieve pain in more advanced cancers.

Neo-adjuvant radiotherapy (before surgery)


If a tumor is large, radiotherapy can shrink it, making it easier and less harmful to then surgically remove it.

Adjuvant radiotherapy - given after surgery


The aim is to eliminate the cancer cells that remained behind. Doctors at St Jude Children's Research Hospital, TN, USA reported that aggressive surgery followed by targeted radiotherapy is the optimal means by which a rare form of childhood brain cancer (Ependymoma) should be treated, as it significantly improved survival rates, compared to children who received surgery alone.

Combination therapy - radiotherapy combined with another type of therapy















In some cases, chemoradiation - radiotherapy combined with chemotherapy - is more effective. A Canadian-European study found that giving patients with glioblastoma the chemotherapy drug temozolomide in combination with radiotherapy increases their survival rate, compared with those receiving radiotherapy alone, and this improvement persists for up to 5 years.


Radiotherapy combined with hormone therapy has been shown to significantly reduce mortality in men with prostate cancer, according to The Prostate Cancer Charity, UK.

Total body irradiation (TBI)


The whole body receives radiation. This may be used for leukemia or lymphoma before a bone marrow transplant - the aim is to destroy the bone marrow cells. Researchers from the Institut Louis Bugnard found that TBI may damage fat tissue.

Sometimes radiotherapy is an effective alternative to surgery
Researchers in Leeds, England, reported that radiotherapy is as effective as surgery in treating bladder cancer. They found that survival rates for patients who underwent a radical cystectomy (surgical removal of the bladder) were the same as for those who just received radiotherapy.
When to administer radiation therapy?
Some cancers develop faster than others. Whether to administer radiotherapy promptly often depends on this, as well as other characteristics of some cancers. For cancers, such as breast and head and neck cancers, the risk of the cancer recurring increases if radiotherapy is delayed, according to scientists at the Cancer Research Institute, Kingston, Ontario, Canada, and Cross Cancer Institute, Edmonton, Alta, Canada.
How long does a course of radiation last?
A course of radiotherapy may last from less than a day to a number of weeks. According to the National Health Service (NHS), UK, most patients will undergo one fraction (session) per day from Monday to Friday with a break at the weekend to allow the body to recuperate.
What is 'a fraction' in radiation?
In each case the radiologist will decide what the full dose for the treatment should be. This cannot be given all in one go because it would harm the patient. So, it is divided up into fractions. During each session the patient will receive a fraction of the total dose. A session is often called a fraction.
Types of radiation therapies
External beam radiation



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High-energy beams come from a device outside the human body - this could be in the form of X-rays, cobalt irradiation, electrons and protons.


The beams are aimed at a specific point in the body - where the tumor is. The radiation destroys the genetic material that controls how cancer cells grow and divide. A certain number of healthy cells are also damaged by this kind of treatment. The aim is to hit as many cancer cells as possible while damaging the minimum number of healthy ones. Most damaged healthy cells are able to repair themselves.


The patient will feel no pain during each session. However, he/she may experience temporary side-effects later on, which may include pain or discomfort.


External radiation may be given in other forms:

Conformal radiotherapy - the standard external radiotherapy machine is used, but metal blocks are placed in front of the radiation beam. This changes the beam's shape. The aim is to make the beam 'conform' to the shape of the tumor. If the beam is shaped like the tumor fewer healthy cells will be damaged when doses are high. This results in side effects being less severe and not so long-lasting.

Intensity modulated radiotherapy (IMRT) - computers regulate the machine's emission so that very precise radiation doses are aimed at certain parts of the tumor. A 3-D scan of the tumor is done beforehand so that the radiologist can work out the exact intensity of the dose according to the tumor's shape. The tumor receives a high dose of radiation, leaving nearby healthy cells exposed to very low doses. Patients undergoing IMRT tend to have fewer side effects, compared to those on standard treatments. US scientists reported in a study that the application of modulated radiotherapy in the treatment of bowel cancer can enhance the results obtained by means of other conventional therapies without increasing toxicity.

What happens during an external radiation session?


Unless the patient is also receiving chemotherapy as well, or is not well, he/she will go home as soon as the session is over.


The patient will be positioned on a treatment table and the radiotherapy machine will direct the high-energy rays at a specific part of the body. While this happens it is important to keep completely still so that the targeting is as perfect as possible.


The radiology team will be in another room. They can see the patient at all times and the patient can communicate with them. They stay in another room because a lifetime of light radiation exposure would gradually build up eventually start to harm them.


The whole process should not take more than a few minutes.


Internal Radiotherapy


The radiotherapy is given from inside the body. The patient may drink a liquid which is absorbed by cancer cells, or radioactive material may be placed near the tumor. The two types of internal radiation therapies include:

Radioactive liquids - these are either consumed as a drink or injected into the patient. For cancers of the blood the liquid will contain phosphorous, secondary bone cancer patients will be given strontium, while iodine will be used for thyroid cancer.

Radioactive implants (brachytherapy) - this may be in the form of metal seeds (pellets), tubes or wires. They are placed very near to the tumor. The implant may stay in the body for just few minutes or a number of days - this depends on the type of cancer and tumor. There are cases when the implants are never taken out.

If the patient is hospitalized and has radioactive implants or liquids, the hospital will take measures to protect staff and visitors from radiation exposure. Some patients may become alarmed at these measures; wondering about the safety of what they have subjected themselves to. It is important to remember that the high radiation doses are aimed at the cancer, while the other healthy cells receive a much lower dose - even if some are damaged, most will recover. The medical team has determined that the benefits of the radiotherapy are greater than the risks.


As soon as an implant is taken out the patient has no more radioactivity in his/her body - it does not linger. The radioactivity in liquid treatments takes a few days to disappear. In both cases, when the radiation is gone the patient is not a risk to anyone around him/her.


In most countries the patient will stay in hospital until the implant is removed or the effects of the liquid have gone. Those with permanent implants have such a low dose that they are not usually a risk to others. The radiology team will advise the patient on safety steps.


Some studies have indicated that internal radiotherapy results in a better quality of life for the patient whose cancer is in the pelvic region, compared to external therapy. Dutch researchers said that this quality of life benefit would be an important factor to take into account when comparing the risks and benefits of using vaginal brachytherapy or external beam pelvic radiotherapy after surgery for endometrial cancer patients.
Combining magnetic resonance imaging (MRI) with radiotherapy
Real-time image-guided radiotherapy, combining radiation treatment with non-invasive MR imaging, is far less harmful for patients as it leaves less healthy tissue damaged and gives radiation oncologists the possibility of instantly modifying the treatment dose as tumors change in size and shift, say researchers at the University Medical Centre Utrecht in the Netherlands.
What are the side effects of radiotherapy?
As radiotherapy inevitably damages some healthy cells most patients will experience side effects. Their severity and duration will depend on:

What part of the body was targeted
The radiation dose
The speed of recovery of the damaged cells

On some occasions side-effects may be felt during a radiotherapy procedure, while others may not emerge for weeks, and even months. Below are some of the side-effects most commonly reported by patients:

Fatigue - the most common symptom. Often felt before the whole radiotherapy course ends. If doctors determine that it is caused by anemia (lack of red blood cells) they may order a blood transfusion. Experts say that light exercise can sometimes help relieve symptoms as well as accelerating recovery.

Diarrhea - if the beams were aimed at the abdomen diarrhea is a common side effect. Patients commonly report symptoms within a few days of the commencement of treatment. As the radiotherapy course progresses symptoms may get worse. The patient will usually get better a few weeks after treatment is completed. If there is blood in the stools the doctor must be told straight away.

Heart disease - this is a risk if the heart is in the line of fire of the radiation beam, as might be the case in some breast cancer treatments - when the breast tumor is on the left side a small part of the heart is within the treatment range. Scientists from the University of Leicester, England, found a way to identify breast cancer patients at risk of heart disease after radiotherapy.

Nausea - this may occur at any time during the course of treatment, or a short time afterwards. It is important to tell your doctor because it is easily treatable with medication.

Muscle and joint stiffness - this may also be accompanied by swelling in the area that received the energy beams. If symptoms are severe the doctor may refer the patient to a physical therapist (UK/Australia: physiotherapist).

Sore skin - areas that were hit by the radiation beam may become reddened and sore. Patients should protect that area of skin from sunlight and cold winds, as well as from perfumed soaps. Scratching and rubbing will irritate the skin more.

Lower libido (lower sex drive) - this may affect both male and female patients. Their ability to participate in sex may also be affected.



Women - A woman's vagina may become narrower if the beams are aimed at that area - a vaginal dilator will help prevent this narrowing. Experts say that regular sex after treatment will help prevent vaginal narrowing too. Vaginal dryness is also possible.

Men - If the beams are aimed at the pelvic or genital area, as may be the case with prostate cancer treatment, nerve bundles involved in erectile function may be affected and the man may have problems either getting or sustaining an erection. This side effect is usually temporary.


Fertility problems



Women - if the beams are aimed at the pelvic area there is a risk of early menopause and infertility. If the patient is young she needs to discuss this with her doctor beforehand. Some of the eggs may be removed and stored if the patient does not need radiotherapy immediately. It is important to remember that radiation therapy to other parts of the body do not have the same risk.

Men - although the risk of infertility is usually lower for men than for women, there is still a risk. It is important to talk to the radiologist beforehand. Male sperm can be stored.


Loss of appetite - patients who experience fatigue and nausea usually don't feel like eating. If the radiation was aimed at the head, neck or chest it might be difficult to swallow. Changing from the standard three meals-a-day regime to many little meals may help. Drinking through a straw may make drinking easier.

Dry mouth (xerostomia) - if the therapy targeted the head, neck or mouth the salivary glands may produce less saliva. The glands will usually recover after treatment, although this may take several months. A small number of patients never recover. The doctor may prescribe a medication for this, such as Pilocarpine (Salagen). Remember that alcohol, caffeine and cigarettes dry the mouth.

Hair loss - some patients may develop temporary alopecia (hair loss). Although losing hair has does not damage the health, some people may find it distressing and embarrassing. If you lose your hair and find it affects you, consider the following steps below:



Ask your doctor to refer you to a counselor who is trained at helping people work problems through.

Go to a local cancer support group meeting. Talking to people who share similar experiences to yourself may help.

Consider getting a wig. Many patients have reported that it helped them a lot.


How sensitive are cancers to radiotherapy?

Highly radiosensitive cancer cells - these are destroyed with modest doses of radiation. Examples are leukemias, most lymphomas, and germ cell tumors. However, as leukemia is all over the body and radiation therapy cannot be beamed everywhere, it is not generally curable with radiotherapy. If the lymphoma is localized in one area of the body the chances of a cure with radiotherapy are much higher.

Moderately radiosensitive cancer cells - these require a higher dose to achieve a cure. Radiotherapy is commonly used during the early stages of these cancers: non-melanoma skin cancer, head and neck cancer, non-small cell lung cancer, cervical cancer, anal cancer, and prostate cancer.

Highly radioresistant cancer cells - these require a very high dose. Examples are renal cell cancer and melanoma.

Metastatic cancers, regardless of how radiosensitive they are, are usually incurable with radiotherapy because one cannot treat the whole body.


Small tumors respond better to radiation therapy than large ones. In order to overcome this problem surgical resection is sometimes performed, or chemotherapy is used to shrink or remove most of the tumor before radiotherapy. Some drugs may make the tumor more radiosensitive, such as Cisplatin, Nimorazole, and Cetuximab.


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