The Principle Behind The Effectiveness Of Radiation Therapy
Either by itself or in combination with other treatments such as chemotherapy, radiotherapy is a fundamental part of many cancer treatments, and millions of people will set foot into a radiotherapy centre to start or continue cancer treatment, as well as other abnormal growths and lesions.
Whilst the concept is shared amongst the wide variety of radiotherapy treatments, there is a broad spectrum of different methods used to achieve different results, from the highly targeted brain tumour-targeting Gamma Knife methods to generalised palliative radiotherapy for soothing advanced-stage patients.
For most people who are diagnosed with cancer and prescribed a course of radiotherapy, what primarily matters is that it is safe, it is effective and it will remove the cancer or reduce the potential danger it can cause to life.
However, there are guiding principles behind its effectiveness, and by understanding these, we can understand when and why radiotherapy is used and why continuing advances in technology help to improve effectiveness and reduce risk at the same time.
The root of this lies in the very reason why cancer causes harm in the first place.
Why Does Cancer Cause Harm?
There are hundreds of different types of cancer, each with varying levels of severity, different courses of treatment and targeting different parts of the body. However, all of them are caused by DNA damage which alters the normal ways in which cells grow and die.
These cause mutations that lead to genetic mutations, some of which affect the normal processes that cells use to grow, die and repair themselves. These changes are known as the hallmarks of cancer, and there are eight primary examples:
- Growing without external growth signals (self-sufficiency).
- Resistance to signals preventing cell growth.
- Evading programmed cell death (anti-apoptosis).
- The infinite potential for replication with damaged chromosomes (cell immortality).
- The ability to form new blood vessels to stimulate growth (sustained angiogenesis).
- The ability to invade other tissue and spread to other organs and parts of the body (metastasis).
- Deregulating the metabolism and generating energy through ways other than conventional respiration (often described as the Warburg effect).
- The ability to evade the immune system despite causing inflammation in cells.
As well as this, instability of genes and chronic inflammation have been seen as characteristics that cause cancer cells to develop.
This means that the key to getting rid of cancer is to stop these traits, and the main way to do this is to destroy the DNA of a cancer cell.
Why Radiotherapy Works So Well
Radiotherapy uses particles or waves of radiation with high levels of energy that are targeted at cancer cells and damage their DNA in such a way that it will stop them from dividing rapidly, which stops cancer’s primary form of harming cells and harming people.
What makes this so useful is that the very mutations that lead to cancer developing and proliferating also make them especially vulnerable to DNA damage, as they lack the ability to repair cells with anywhere near the level of effectiveness as healthy cells do.
In most cases, this makes radiotherapy the primary form of treatment, particularly when it is carefully targeted and the person being treated is appropriately immobilised to ensure a high level of accuracy with treatment.
However, in some cases, cancer cells have a resistance to radiation, but this is the exception, rather than the norm.
What can be more of an issue, and the reason why specialist cancer treatments such as Gamma Knife exist, is how radiotherapy can damage surrounding tissue.
This is why immobilisation equipment and frames are used to precisely hold patients in place to ensure that the beam of radiation hits tumours and lesions, instead of any surrounding tissue.
Besides immobilisation, there are other ways in which this concern is being thwarted, such as more intense bursts of radiation that cause less damage to surrounding tissue, as well as heavier ions that damage cancer cell DNA more effectively.
Beyond this, there are promising evolutions in diagnostic equipment that would vastly improve the treatment pathway by allowing tumours to be tracked in the body in real-time.
As tumours can move in the body based on breathing and other impossible-to-stop subtle movements, using real-time body scanning equipment such as MRI, ultrasound or X-ray induced radiation acoustic imaging to track where a tumour is located and modify treatments accordingly.
The more precise the radiation dose, the less damage it will cause surrounding tissue, making it more effective and more viable in cases where treatment would otherwise be unviable or too risky to attempt.
