What is radiotherapy and how does it work?

Cancer is a generic name given to a group of diseases that involve uncontrolled multiplication of abnormal cells. The cells grow in size, affecting the original and adjacent organs and tissues. Radiation therapy uses radiation to kill or damage these abnormal cells and stop them from growing and multiplying.

Cancerous cells are more susceptible to radiation than healthy, non-cancerous cells because of their abnormal and unstable nature. Healthy, non-cancerous cells are much better at recovering from exposure to radiation and will normally repair themselves, but the cancerous cells cannot recover.

To use the difference between normal and cancerous cells most effectively, radiotherapy is usually delivered in daily intervals called ‘fractions’. This allows time between treatments for the healthy cells to repair and the cancer cells to die off.

Radiotherapy requires a complicated planning process because Radiation Oncologists will optimise the radiation dose to treat the cancer, while minimising (and where possible avoiding) dose to healthy organs and tissues surrounding the cancer.

How is radiotherapy delivered?

There are two main types of radiation therapy: External Beam Radiation Therapy (EBRT) and Brachytherapy and both of these are available at the Hunter Cancer Centre:

• EBRT - During external beam radiotherapy, the radiation oncology team uses a machine called a linear accelerator (Linac) to direct high-energy X-rays at the cancer.

• Brachytherapy - Otherwise known as Internal radiotherapy, this involves placing radioactive sources (radioactive seeds) inside the body.

External Beam Radiotherapy (EBRT)

IN EBRT the radiation is generated by a machine called a Linear Accelerator(also known as a Linac). This converts electricity into radiation and will produce high-energy X-rays in a variety of different energies depending on what is best suited for your cancer.

Using advanced treatment planning software, the size and shape of the radiation beams can be controlled to effectively treat your tumour whilst sparing the surrounding normal tissue.

There are several different types of EBRT and you may hear the following mentioned:

• Intensity Modulated Radiotherapy (IMRT) : A special form of EBRT involving the delivery of hundreds of small radiation beams with different intensities, entering the body from a number of different angles.

• Image Guided Radiotherapy (IGRT) : involves repeated imaging of the tumour during treatment. It is used in nearly all IMRT treatments to ensure accuracy to the millimeter.

• Volumetric Modulated Arc Radiotherapy (VMAT or RapidArc) - single or multiple radiation beams sweep in uninterrupted arc(s) around the patient speeding up treatment delivery

• Stereotactic radiosurgery (SRS) - SRS is used to treat small tumours with well-defined edges

Treatment with EBRT usually takes between 10 and 20 minutes per fraction (treatment).

Brachytherapy

Brachytherapy involves radiation delivered from a tiny source implanted directly into or next to the tumour. These sources produce gamma-rays, which have the same effect on cancer cells as X-rays. This treatment reduces damage to surrounding healthy tissue, thereby limiting side effects.

There are two main types of brachytherapy: low dose rate (LDR) and high dose rate (HDR). Genesis Cancer Care developed Australia's first integrated brachytherapy unit at the Mater hospital and we now offer LDR at our Newcastle Site.

Where does radiotherapy fit into the treatment journey?

The use of radiotherapy as part of your treatment plan will depend on your diagnosis. For some tumours e.g. skin cancer, prostate or larynx, radiotherapy could be the only course of treatment, but for others, it may form part of a wider care plan.

Radiotherapy can increase the effectiveness of other treatments and you can be treated with radiotherapy before surgery to help shrink a tumour and allow less extensive surgery than would otherwise have been needed. Alternatively you may be treated with radiation after surgery to destroy small amounts of cancer cells that may have been left behind.

For example, if you have breast cancer, you may have surgery to remove the tumour first, chemotherapy to destroy cancer cells that may have travelled to other parts of the body and then radiotherapy to destroy any remaining cancer cells.

The best outcomes for patients occur when treatment plans are determined through discussions between multi-disciplinary cancer medical specialists. These specialists will review your case and use their expertise to determine the best combination of treatment and in which order you should receive it.

How to find out more

We have a wealth of information on our website including the treatment pathway, planning process, common side effects and FAQ’s.

www.cancer.com.au

Some other useful links:

Radiation Oncology - www.targetingcancer.com.au

The Cancer Council - www.cancer.org.au