Modern radiation therapy for cancer of the left breast - Precise, effective and well tolerated
Experience has shown that all patients who have undergone breast conservation surgery benefit from radiation therapy.
The purpose of irradiation is to avoid unnecessary amputation of the entire breast and still have the same assurance that the cancer in the breast will not return. Thus, the quality of life of the affected patients could be significantly improved with the same therapeutic success.
This is because the radiation kills microscopic tumor foci, which are usually hidden in the vicinity of the visible tumor (but can also be in other places in the breast).
However, one of the big challenges is the cancer of the left breast, because here the heart is close to the radiation area and one wants to avoid damage to the heart by the radiation in any case.
What has happened so far…
A method often used in recent years is irradiation in the phase of deep breathing with stopped air. This raises the chest and the very important distance to the heart is increased and thus the sparing is better.
However, experience has shown that this method is perceived by many patients as exhausting and the implementation is not always successful.
The new method…
A new method, which is very convenient for the patients, is the VMAT – modulation of the irradiation fields via a special planning software. With this very computationally intensive preparation method, the distribution of the radiation dose is very precisely adapted to the shape of the breast. As a result, the load on the heart can be optimally reduced.
In addition, in the course of this preparation, the change in shape of the breast during breathing is also taken into account. This enables stable treatment with normal breathing and makes the correct implementation of the planned therapy safe and comfortable.
Thus, a treatment session itself lasts only 5 – 10 minutes during which one lies relaxed on the treatment table and breathes normally. The treatment is painless and well tolerated.
A treatment series is carried out over a continuous sequence of 15-20 sessions. ( 1 session per day, 5 sessions per week on Mon-Fri, total 3-4 weeks in a row). The division into several sessions is necessary to make the treatment well tolerated.
Common side effect is a temporary feeling of mild fatigue and a warming and swelling of the breast at the end of the entire treatment series similar to a sunburn. All these side effects usually subside after a few days.
An example from practice
But what does this modern method mean concretely for the protection of the heart?
The valid recommendation for the protection of the heart [1] is that the heart should receive an average dose of less than 26 Gy in order to avoid damage (heart mean < 26 Gy).
From experience, one speaks of a good plan when the dose to the heart is less than 9 Gy (heart mean < 9 Gy) and of a very good plan when the dose is less than 3 Gy (heart mean < 3 Gy).
Now how does it look concretely with the load of the heart with the help of the new method?
A picture says more than 1000 words….
The graph shown here shows the dose distribution in a patient with breast cancer on the left who was treated with the modern method.
The red part shows the treatment dose in the breast, the more the color changes towards blue, the lower the dose (red 100%, blue 10%). The graph shows that the dose nestles in the shape of the breast and only a few centimeters further hardly any radiation arrives.
Source Amethyst Radiotherapy Vienna
And what about radiation exposure to the heart? Can a dose below 9 Gy or even below 3 Gy be achieved?
The answer is yes. In the case of this patient, the dose is only 1.34 Gy (heart mean = 1.34 Gy).
Source Amethyst Radiotherapy Wien
Literature
- Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC), “Use of normal tissue complication probability models in the clinic.” (Marks LB, Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S10-9.)
Author Dr. David Kuczer, Facharzt für Radioonkologie und Strahlentherapie
FLASH Radiotherapy
What Is FLASH Radiotherapy?
Not every treatment at a radiotherapy centre is alike, and different techniques, dose intensities and applications are used for the wide range of treatments radiotherapy is involved in.
Low doses are used as part of pain relief for terminal cases, whilst stereotactic radiosurgery techniques such as Gamma Knife use high doses of targeted radiation to excise lesions in parts of the brain where more standard radiotherapy would pose too much of a risk. Over the past few months, specialists in the field of radiotherapy and radiation oncology have explored another type of radiotherapy treatment that uses an ultra-high dose of radiation for a very small amount of time in a field currently known as FLASH Radiotherapy.
FLASH Radiotherapy is named for the FLASH effect, a relatively recent discovery about the efficacy of high-dose radiation delivered in a fraction of a second. The theory is that by doing this, the tumour-destroying effects of radiotherapy can be easily attained quickly without the damage to healthy tissue caused by exposure to more conventional radiation techniques that necessitates the use of techniques like Gamma Knife ordinarily. It also reduces some of the uncertainty with radiation doses caused by imperceptible movements, breathing and other aspects that often require patients to be secured in place before the treatment begins.
Several tests in the eight years since the initial discovery of the FLASH effect have managed to replicate the results and strongly suggest its effectiveness, but what is still unclear is how it works. Specifically, why does the split-second FLASH effect damage cancerous tissue whilst sparing healthy tissue and allowing it to grow again? The answers to this are, as of the end of 2022, still somewhat unclear, and as a result FLASH radiotherapy has been used in somewhat limited capacities, such as a test case on a skin cancer patient.
The relative lack of clarity surrounding how it works and how to most optimally deliver the FLASH effect currently limits its use outside of experimental test cases, but as more information is learned, it has the potential to be a game-changing treatment technique.