How Radiation Therapy Is Used as a Treatment for Cancer

September 8, 2024

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How Radiation Therapy Is Used as a Treatment for Cancer

Radiation is one of the most common treatments for cancer. Radiation treatment is called by other names like radiation therapy, radiotherapy, irradiation, and X-ray therapy.

What is Radiation Therapy?

Radiation therapy uses high-energy particles or waves such as X-rays, gamma rays, electron beams or protons, to destroy and damage cancer cells in the body. Radiation therapy is used either independently or alongside other treatments like chemotherapy or surgery to treat cancer.

Radiation is a very precise method. It aims beams directly at the cancer cells and protects the healthy tissues from high doses of radiation. Radiation therapy can treat almost any type of cancer. Sometimes radiation therapy can also treat conditions other than cancer like non-cancerous, benign tumours.

How Radiation Therapy Kills Cancer Cells

Radiation therapy treats cancer and eases cancer symptoms. When used in treatment, radiation therapy can cure cancer, prevent it from returning, stop or slow its growth. When it is used to ease symptoms, it is called palliative treatment.

In a normal human being, our cells grow and divide to form new cells. It is important to note that cancer cells grow and divide faster than normal cells. When radiation is used, it works by making small breaks in the DNA inside the cells. These breaks prevent the cancer cells from growing and dividing. It causes them to die. The body breaks down and removes the dead cells. There is a possibility that normal cells near the cancer can also get affected during radiation therapy. However, many of them recover and go back to working as they should.

Radiation therapy is a local treatment and is usually aimed at and affects only the part needing treatment. Normally, radiation treatments are very sharp and target only the cancer cells and do not affect the healthy cells nearby.

Types of Radiation Therapy

There are two main types of radiation therapy: external beam radiation therapy (EBRT) and internal radiation therapy. Both these types of radiation therapy work on destroying the DNA in the cells that they are targeted at. When there is no DNA, the cells do not receive instructions which tell them how to grow and multiply. Thus, the cancer cells die and resultantly the tumours shrink.

External beam radiation therapy (EBRT)

This is a very common type of radiation therapy where a beam of high-energy radiation is targeted towards the tumour. It is a very precise treatment and the radiation oncologist designs a treatment plan that targets only the tumour and not the healthy cells.

There are many types of EBRT

3D conformal radiation therapy: Using CT scans and computer software, a 3D model of the tumour is created. The machine uses the model as a guide and targets beams directly at the tumour.
Intensity-modulated radiation therapy (IMRT): It is an advanced form of radiation therapy which uses radiation beams that vary the intensity of the dose. So while the tumour receives a higher dose, healthy tissues around it receive lower doses.
Arc-based radiotherapy: Here the energy beams of varying intensity are directed in a rotational, arc-like pattern. This method delivers radiation faster than traditional methods.
Image-guided radiotherapy (IGRT): The radiation machine obtains a low-dose X-ray or mini CT scan before the treatment. Using the image, the treatment is aligned resulting in precise delivery of radiation.
Particle therapy: Here protons are used instead of photons (X-rays). Protons are more effective for certain people.
Stereotactic radiosurgery: A gamma knife surgery that uses high doses of focused radiation to destroy brain tumours. These surgeries are extremely precise. No cutting is done and treatment is very quick.
Stereotactic body radiation therapy: Like the gamma knife surgery, it is used to target tumours outside of the brain. It also uses high does of focused radiation and no actual surgery happens but the tumour is eliminated.
Intraoperative radiation therapy (IORT) It is used to deliver radiation during a surgery. When surgery is used to remove a tumour, IORT is used to destroy any remaining cancer cells that are not safe to remove surgically.

Internal radiation therapy

In this therapy, radiation is placed inside your body, close to the cancer cells. Smaller tumours are treated with this like those in the head, neck, breast, cervix, uterus, or prostate.

Internal radiation is administered both is solid and liquid form. There are two types of internal radiation therapy.

Brachytherapy: a solid, radioactive seed is implanted in the tumour or beside it. The seed releases radiation to a small area and kills the cancer cells. Implants or seeds release either low or high doses of radiation depending on the need. Some implants are temporary while others are permanent and stay in your body forever but stop releasing radiation.
Systemic therapy: In this, a liquid radioactive material is sent through your blood to find and destroy the cancer cells. The liquid can either be swallowed or given through an IV. There is also radioimmunotherapy in which a radioactive protein recognizes cancer cells, attaches itself to them and releases radiation to kill them.

Radiation Therapy and Cancer Treatment

Radiation therapy cannot reach all parts of the body. So typically, a cancer that has spread to various parts of the body cannot be effectively treated with radiation. Radiation is used to treat cancer either alone or in combination with other treatments. It has various purposes:

Cure or shrink early-stage cancer: Some cancers are sensitive to radiation. These can shrink or completely go away. For some people, anti-cancer drugs and chemotherapy is first used. In others radiation can be used either before a surgery to shrink the tumour or after the surgery to prevent it from coming back. Radiation is preferred over surgery because it causes less damage to the body. Certain drugs called radiosensitizers make cancer cells more sensitive to radiation and therefore helps radiation to work better. Many times, these drugs and radiation are given together to address the problem more effectively.
Prevent cancer from recurring: Normally cancer cells spread to other body parts from the region where they originally started. Oncologists believe that even though they are not visible on CT scans or MRI, they would have already spread. Depending on the need of the patient, apart from radiation to the tumour and treatment for the existing cancer, radiation is given to prevent it from spreading to other parts.
Treating advanced cancer: In some people, the cancer spreads very widely all over the body. For them radiation is used to reduce the tumours and shrink them so that the person can feel better. They may have reduced pain, better ability to swallow food, breathe easily and better bowel movement thanks to radiation. This is called palliative radiation.
To treat recurrence: When a cancer has returned, radiation is used. If radiation has already been used earlier, then it may not be possible to give more radiation in the same place. Also some tumours do not respond well to radiation, hence radiation is not effective when it recurs.

Side Effects and Management

Radiation therapy is spread over multiple treatment sessions, so a patient does not receive the full dose at once. The treatment schedules are planned in such a way that the healthy tissue gets time to recover between sessions. This healing time reduces any side effects that may be there.

IT is possible that some patients have unpleasant side effects of radiation. Side effects could be any of the following:

Fatigue
Nausea or vomiting
Headaches
Diarrhoea
Skin irritation or a dry and itchy scalp
Loss of hair
Mouth sores
Reduced appetite
Pain while swallowing due to dry mouth and sore throat caused by radiation
Burning sensation in throat and chest
Frequent peeing and burning sensation while peeing
Abdominal bloating and cramps
Urgent bowel movements

It is important to wear loose clothing over the treatment area. Do not rub, scrub or scratch the skin in that area. You must avoid using powders, cream, perfumes, deodorants, or other products in that area. Use lukewarm water and mild soap to clean the area. Protect the area from the sun with protective clothing.

It is important to eat a well-balanced diet to get enough vitamins and minerals that you need. Mild physical exercise can help reduce fatigue. If you are feeling anxious or depressed, seek the help of a psychologist or counsellor.

Conclusion

Radiation therapy is used at different times and for different reasons during your cancer treatment. It can completely treat a tumour. At other times, it can be used to shrink a cancer before surgery or after surgery to treat cells that cannot be removed surgically. Radiation therapy is often used along with other therapies like chemotherapy and medication.

Frequently Asked Questions

1. What is radiation therapy?

Radiation therapy uses high-energy particles or waves such as X-rays, gamma rays, electron beams or protons, to destroy and damage cancer cells in the body.

2. How long does radiation therapy take?

Treatment schedules are planned depending on the need of the patient. Each treatment may take 15 to 20 minutes for positioning and a minute or two for each treatment field.

3. Does radiation therapy have side effects?

Yes, side effects like fatigue, nausea and vomiting, diarrhoea, hair loss, reduced appetite and skin irritation are possible.

4. Does radiation therapy hurt?

Radiation therapy does not cause any pain, however, the treatment table may be uncomfortable. You cannot see, smell or feel the radiation when it is administered.