Radiotherapy: How It Works, Types, Side Effects and What to Expect

What Is Radiotherapy?

Radiotherapy, also called radiation therapy, is a cancer treatment that uses high-energy radiation to damage the DNA of cancer cells and stop them from growing and dividing.

It is one of the most commonly used cancer treatments and may be given alone or together with surgery, chemotherapy, immunotherapy or other treatments.

Radiotherapy is carefully planned so that the highest effective dose reaches the tumor while exposure to nearby healthy tissue is reduced as much as possible.

Why Is Radiotherapy Used?

Radiotherapy can be used for different purposes depending on the type and stage of cancer.

It may be used to:

• Destroy a tumor completely
• Reduce the size of a tumor before surgery
• Destroy remaining cancer cells after surgery
• Treat cancer together with chemotherapy
• Control cancer that cannot be removed surgically
• Reduce pain, bleeding or other symptoms in advanced cancer

The goal of treatment can therefore be curative or palliative.

What Are the Main Types of Radiotherapy?

There are several ways radiation can be delivered.

External Beam Radiotherapy

External beam radiotherapy uses a machine outside the body to direct radiation at the tumor.

The machine does not touch the patient. Instead, it moves around the body and delivers radiation from carefully planned angles.

This is the most common form of radiotherapy and can be used for many different cancers.

Modern systems use imaging and computer-based planning to shape the radiation dose around the tumor.

What Is IMRT?

Intensity-modulated radiation therapy, or IMRT, is an advanced form of external beam radiotherapy.

It allows doctors to adjust the intensity of radiation beams and deliver them from multiple angles.

This can help concentrate the dose on the tumor while reducing radiation exposure to nearby healthy organs.

IMRT is commonly used when tumors are located close to sensitive structures.

What Is Brachytherapy?

Brachytherapy is a type of internal radiotherapy.

Instead of sending radiation from outside the body, a radioactive source is placed inside or very close to the tumor.

The source may be temporarily inserted using an applicator or catheter, or in some treatments a small radioactive implant may remain in the body.

Brachytherapy is used for certain cancers, including some cancers of the:

• Prostate
• Cervix
• Breast
• Head and neck
• Eye

Because the radiation source is close to the tumor, a high dose can be delivered to a small area while limiting exposure to surrounding tissues.

How Is Radiotherapy Planned?

Before treatment begins, patients usually attend a planning appointment.

A CT scan is often performed while the patient lies in the exact position that will be used during treatment.

The radiation oncology team then uses computer software to determine:

• The exact treatment area
• Radiation dose
• Beam angles
• Number of treatment sessions
• How nearby healthy organs can be protected

Small skin marks or positioning devices may sometimes be used to help reproduce the same position during each session.

What Happens During a Treatment Session?

External radiotherapy sessions are usually painless.

The patient lies on the treatment table while the radiotherapy machine moves around them.

The treatment team leaves the room while radiation is delivered, but they can see and communicate with the patient throughout the session.

The actual radiation delivery usually takes only a few minutes, although positioning and preparation can make the appointment longer.

Patients do not normally become radioactive after standard external beam radiotherapy.

How Many Radiotherapy Sessions Are Needed?

The number of treatments varies greatly.

Some patients may require only one or a few sessions, while others receive treatment five days a week for several weeks.

Each individual treatment is called a fraction.

Dividing the total radiation dose into fractions can allow healthy tissue time to recover between treatments.

The exact schedule depends on the type of cancer, its location, treatment goal and radiation technique being used.

What Are the Common Side Effects?

Radiotherapy can affect healthy cells close to the treatment area, so side effects depend strongly on which part of the body is treated.

Common effects may include:

• Fatigue
• Skin redness, dryness or irritation in the treated area
• Temporary hair loss in the treatment area
• Nausea when certain areas are treated
• Changes in appetite
• Mouth or swallowing problems after head, neck or chest treatment
• Diarrhea after abdominal or pelvic treatment
• Urinary symptoms after pelvic treatment

Most side effects gradually improve after treatment finishes.

However, some effects may develop months or even years later, which is why long-term follow-up can be important.

Does Radiotherapy Cause Hair Loss?

Radiotherapy only causes hair loss in the area being treated.

For example, radiation to the head may cause scalp hair loss, while treatment to another part of the body will not usually affect scalp hair.

Hair often grows back after treatment, although regrowth may depend on the total radiation dose.

Can Radiotherapy Be Combined With Chemotherapy?

Yes.

Some cancers are treated with chemotherapy and radiotherapy at the same time. This is known as chemoradiotherapy.

Certain chemotherapy medicines can make cancer cells more sensitive to radiation, potentially increasing the effectiveness of treatment.

However, combining treatments can also increase side effects, so patients require careful monitoring.

What Happens After Radiotherapy?

After treatment is completed, patients attend follow-up appointments to monitor their recovery and evaluate how the cancer has responded.

The tumor does not always disappear immediately after radiotherapy.

Radiation can continue damaging cancer cells after the final treatment session, so the full effect may take weeks or months to become clear.

Follow-up may include:

• Physical examinations
• Blood tests
• CT, MRI or PET scans
• Monitoring of treatment side effects
• Assessment for additional treatment if required

Is Radiotherapy Safe?

Radiotherapy uses carefully calculated doses and modern treatment systems are designed to deliver radiation precisely.

However, radiation can still affect nearby healthy tissues, which is why treatment planning and accurate patient positioning are extremely important.

The benefits and possible risks should be discussed with a radiation oncologist before treatment begins.

Choosing a Radiotherapy Center

Radiotherapy requires close cooperation between radiation oncologists, medical physicists, radiotherapy technicians and other cancer specialists.

Patients who need radiation treatment may benefit from a center with modern imaging, advanced treatment-planning technology and experience treating their specific type of cancer.

The most appropriate radiotherapy technique depends on the tumor type, its location, nearby organs and the overall treatment plan.