04 JUNE 2016
Radiotherapy: What the treatment is all about
Unsure about what radiation therapy involves? Here’s a quick introduction.
Radiotherapy, also known as radiation therapy, is the use of high-energy rays, usually X-rays and similar rays, to treat cancer. It works by destroying cancer cells in a targeted area; normal cells can be damaged by radiotherapy but they can usually repair themselves, whereas cancer cells cannot.
Why is radiotherapy given?
It is one of the main types of treatment for many forms of cancer, and can be applied alone or with chemotherapy or surgery. The use of radiotherapy in cancer treatment is mainly to cure and control the cancer (by shrinking it or slowing its spread), but radiotherapy is also used to relieve pain and bleeding for palliative purposes.
Depending on the type of cancer being treated, radiotherapy may be used before, during or after surgery.
For example, pre-operative or neoadjuvant radiation is used to shrink a tumour so it may be removed by surgery and to ensure that it is less likely to return later. Intra-operative radiotherapy is usually given during surgery and can be administered in the form of external-beam radiation therapy or brachytherapy. Normal tissues located in the vicinity of the tumour are physically shielded from radiation exposure in the process. Post-operative radiotherapy or adjuvant radiation therapy is similar to pre-operative radiotherapy in which it makes the main treatment more effective.
There have been plenty of advancements made in the field of radiotherapy that have seen marked improvements in curing cancer completely and also in reducing the side effects of cancer treatment.
Modes of radiotherapy
The most common form of radiotherapy uses X-rays, gamma rays or photons to kill tumour cells or hinder their growth. This is known as conventional radiation therapy.
Others include intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), 3-D conformal radiation therapy, stereotactic radiation therapy, radiosurgery, and brachytherapy and implants.
Intensity-modulated radiation therapy
This is an advanced form of radiotherapy and uses precise beams of radiation according to the shape of the tumour, minimising exposure of radiation to nearby healthy tissue, and thus the side effects. IMRT uses multiple small radiation beams with different intensities that are carefully controlled.
Image-guided radiation therapy
This uses the on-board imaging capabilities of the linear accelerator to help improve accuracy, positioning and for daily verification of target localisation (positioning). This enables the doctor to reduce the treatment volumes and therefore reduce side effects and normal tissue treated.
3-D conformal therapy
This is now the basic approach for most modern radiotherapy centres. It enables the doctor to visualise a tumour and target it in three dimensions giving better perception of the surrounding.
Stereotactic radiation therapy
This uses detailed imaging, computerised stereotactic localisation with multiple beams in multiple planes for treatment planning. With precise set-ups and image guidance (IGRT) to deliver radiation doses with extreme accuracy. It can be given as a single high dose of radiation or in smaller doses over several sessions for small targets and where tumours may be near critical organs.
This is a non-invasive treatment that delivers tightly focused beams from multiple directions. This allows a strong dose of radiation to be given while reducing exposure of radiation to surrounding healthy tissue. It uses the same concept as stereotactic radiotherapy.
Brachytherapy and implants
This involves implanting radioactive sources into or next to the tumour site. This enables the treatment to be delivered directly to the site, while keeping the surrounding tissue safe from high levels of radiation.
Side effects of radiotherapy
Whichever part of the body you are targeting radiotherapy to, you are likely to experience some sort of side effects to different degrees. Most people only experience tiredness, feeling sick, skin reactions, flu-like symptoms, hair loss, changes in blood and appetite.
There are many ways to manage side effects but your oncologist will be best to provide you with proper solutions as radiotherapy is distinct for each individual. Advancements in the field have also made lots of headway for reduction of side effects for radiation treatment.
Written by Charmaine Ng
Source: Parkway Cancer Centre