Radiotherapy
Patient questions and answers
Dr. Frédéric Dhermain
During the Reunion Zoom of October 20, 2021
PRESENTATION
Dr. Frédéric Dhermain is an oncologist Radiotherapist by training, manager and animator of the Neuro Committee (Polydisciplinary Group, including neurosurgeons) at the Gustave Roussy Institute (Villejuif) since 2003.
Requests can be made by patients, relatives of patients, doctors, and the processing of these requests is made at the latest in the week, at worst within two weeks, but never more. Management is global: not just rays, but also chemotherapy, when necessary.
For meningiomas, the IGR receives 5 to 6 patients per week, or 150 to 200 per year, patients who have brain tumors: gliomes, meningiomas. Malignant tumors are in the majority. 20% are benign tumors, whose meningioma is the largest representative. In practice, there are 1 to 2 indications of radiotherapy for meningioma per week. 2/3 of cases are patients, since we now know that meningiomas are often linked to hormones.
The location of meningiomas is different depending on sex:
- In women : the base of the skull, around the pituitary gland, of the cavernous sinus, therefore very central in the skull
- In humans : the vault of the skull, the wall, therefore rather peripheral
Meningiomas are more often "mild" (as opposed to "clever", which means cancer) in women than in men. In humans, meningiomas are more often clever and less sensitive to treatments.
There are very few very young people, but on the other hand the patients are older and older, because MRIs are more and more frequent. As soon as someone has a headache, we go directly from MRI rather than scann (which is a very good thing!) And so we discover fortuitously of meningiomas.
Indications of radiotherapy
Solange : When you have a tumor of more than 3 cm which crushes the right optic nerve which is not operable because too risky, can we make radiotherapy?
Modern radiotherapy, with photons or protons, is possible on the technical level and without size limit, and even for a meningioma that encloses the optic nerve. In this case, it is obvious that surgery can do nothing. Radiotherapy is possible, even if meningioma is 7 cm, and even if you are 80 years old. You can treat from the smallest to the largest, in terms of age and size.
There are different ways to deliver rays, to dose the rays.
What is needed is that the indication is justified: when surgery seems impossible or not complete, we remove meningiomas that grow or threatening. They must grow, because if they are stable, we can keep them until the last day of his life.
Compression of the optic nerve, and seeing less well, is in itself a symptom, so something must be done, radiotherapy and/or surgery, to limit this compression. For the optic nerve, radiosurgery is not suitable. We need low doses per sessions but spread over 30 sessions and 6 weeks for example.
It is often not worth going on surgery if you cannot remove everything.
Sarah : Should the tumor do less than 3 cm to be able to be treated by radiochurgery?
The size of 3 cm not to be exceeded comes from the history of radiosurgery : in the 1950s, with the creation of Gamma Knife, a radiotherapy apparatus, which emits rays, cobalt rays, therefore photons, which are emitted by natural radioactivity, gamma photons (hence the name of Gamma Knife) which focuses very well on a very small target, which can be a meningioma Metastasis, a neuroma, etc.
The very design of the device and until the very latest version, made you only have one session. The patient arrived the day before in neurosurgery, hospitalization therefore, and once the images were made, the neurosurgeon puts the trepan holes, and the session lasts 40 to 50 min, and can only be done once.
If the tumor is more than 3 cm, the dose is forced to be reduced, because toxicity is too large. Beyond 3 cm, the indication of a single session to the Gamma Knife is no longer possible, but there are lots of alternatives. .
Now, with radiosurgery devices, we can make 3 fractions in J1-J3-J5, on larger volumes. For very large volumes, we can also return to "old" radiotherapy with conventional fractions, which can be a very good alternative to "One Shot" (a single session and very high dose).
In neurosurgery, we do an MRI before and after operation, and the neurosurgeon can say that he has taken everything away and that we are no longer talking about it. In radiotherapy, everything is different: we make rays, we heat the tumor, and little by little it will dry out, but it is a very delayed mechanism in time, for which the results in terms of efficiency are non-progressions, we speak of 'local control'. There is no disappearance, nothing is taken away. In 15% of cases, not only is meningioma stabilized, but it can decrease a little (a few mm in general). And if he compressed the optic nerve, the optic nerve is then released, at least in part, and the eyelid that fell (ptosis) goes up for example.
Radiotherapy techniques
Noëlle: What technique to favor and why?
The difference is on particles. There are 3 types of particles, and there may be a fourth. The radiotherapist still uses 'ionizing' radiation:
- The electrons, the tumor must be superficial, so never the meningiomas.
- Conventional radiotherapy: photonrap therapy, which uses photons, 90 % of the indications.
- Proton therapy, which uses protons (3 centers only in France: Orsay, Caen, Nice): the indications are becoming more and more worn and more only in children.
It is the protons that save the cerebral fabric the most, so these centers receive children in priority. The treatment is done over 6 weeks and in conventional sprawl (small doses per session, 5 sessions per week). The toxicity and efficiency on the tumor are the same as with the photons since we are talking about Gray 'equivalents' (with photons, biologically).
Where the rays pass, the hair falls but it grows back in 2 to 6 months. It is the side effect of brain radiotherapy that goes through the scalp, whatever the particle. The hair is very sensitive to radiotherapy. They can repel, sometimes a little different or more brittle color, but they repel over several months.
Magalie : My neurosurgeon tells me that the tumor I have, namely spheno-orbital, is not treated by radiotherapy. Is it true? For what
The meningiomas present themselves to the imaging of 3 ways:
- They are compact, forming a kind of mass 'full' full, and it is very good indications to photons, but also to protons, a well limited target, of intermediate size (3 to 5 cm), close to the risky organs that are the optic nerve, the optical chiasma, the cerebral trunk.
- They snack/ irritate the bone gradually (an osteo-meningioma) and sometimes the bone part is more important than the fleshy part: the more a bone presentation, the less the radiotherapy works (often the bone part is very stable, and does not necessarily require an operation or an irradiation, that is debated elsewhere.)
Edith : Can we do radiotherapy with a titanium plate?
MRI monitoring is possible, and depending on the indication and discussion between neurosurgeon and radiotherapist (RCP, multidisciplinary meeting), and radiotherapy is possible, with the same doses and the same results.
Cécile: I will be operated at the end of October with a left para sagittal meningioma. There will be a residue, should you already make an appointment?
The neurosurgeon contacts, when he judges him relevant, the radiotherapist upstream, and the patient is informed. But if the residue does not grow after operation, it is not necessarily necessary to radiate it.
So to see if it is growing or if it is a grade 2 (atypical).
Important: after operation, you must request the histological report of the operation , and not be satisfied with what the neurosurgeon says. If it is a grade 3 (clever), you have to chain within 6 weeks with radiotherapy, because we know that it will grow fairly quickly. If it is a grade 2, the discussion is possible, some are more aggressive than others. As a rule, grades 2 do not evolve in grade 3.
Pascale: From what symptoms is envisaged in radiotherapy?
A symptom that becomes invalidating over time, which has an impact on daily life, must be heard and listened to. Even if meningioma does not seem 'to move' to MRI.
Gamma Knife- Cyber Knife
Emmanuelle : Differences between Gamma Knife and Cyber Knife. Why still the "screwed helmet" and why not a thermoformed mask for everyone and any type of radiotherapy?
Gamma Knife has been historically developed and is still widely used by neurosurgeons , they have contributed to its creation, development and dissemination.
Cyber Knife is rather used by radiotherapists , can treat tumors up to 5 cm (while the Gamma Knife stops at maximum at 3 cm).
Both use photons and are very precise (infra-milistical precision).
Currently, there is great progress in compression masks. If you are treated at Cyberknife (unlike protons), you will have a control for each session and in real time of the reality of the dose, where it is issued.
Inside a mask, you can always move, but very little. There is a compromise in a mask to do between 'holding' for 30 to 40 minutes with a very tight mask or with a little more freedom, so more comfortable, but there we can move more.
In most indications, the 1/10 of MM does not count, because the radiotherapists integrate it into their irradiation volume and the patient can move by 1 mm.
Conversely, in certain indications, if we deliver for example 80 to 90 grays in an extremely precise region, ex of arnold neuralgia resistant to all other treatments, and whose only effective treatment is to 'burn' the nerve to remove these intense or even infernal pain, as are huge doses, it is often preferred a surgical fixation (trepan holes) move at all.
For the rest, thermoformed masks are possible (knowing that there are several kinds, which are more or less restrictive).
With the Cyber Knife, the robot adapts in real time if you make a movement during treatment; So the compression may not be too tight.
For claustrophobic people: sophrology, cardiac coherence, visualizations of what was going to happen, work on breathing, meditation.
In Gustave Roussy, session of 3/4 hours with radio manipulators where all questions are answered. And it is also proposed of auriculotherapy, sophrology.
Françoise: What about the necrosis of healthy fabrics after the Gamma Knife?
In single session, the doses are between 5 and 10 times at the usual doses. The classic 'treatments are 2 grays per session. The Gray is 1 joule per kg, an energy unit per kilo of fabric crossed.
The Gamma Knife, which delivers gammas photons, is 15 to 20 grays in 1 session.
Dosimetry (distribution of the dose) is dependent on the machine used.
There is always a very small strip of fabric which is irradiated beyond the tumor, the question is whether it is in the functional zone or not? The so-called functional area is very dependent, it is not 100% possible to identify it only by non-invasive techniques such as functional MRI.
If there is healthy tissue necrosis, you can take care of it in different ways, mainly with corticosteroid therapy.
Why do we know so little about meningiomas?
Because it is not cancerology, it is less 'noble' as a discipline, so it interests the researchers less. It may also be because it is mainly women who have it.
Sequelae
Christelle : What are the negative dental, salivary, nasal, auditory, pituitary repercussions of the fractional irradiation of optical chiasma and optic nerve ?
In the radiotherapy of meningiomas, which takes place in the upper half of the head, there is no salivary or dental incidence. On the other hand, there may first be for hearing, if meningioma affects the hearing nerve (which is called a neuroma or a schwannome ). The radiotherapist can guarantee a non-aggravation of hearing status, very rarely a return to the initial status.
When there is concern, it is especially in the treble, but if the maximum doses tolerable by the cochlea are well respected, the patients do not become deaf and the devices are now increasingly efficient.
When there is a meningioma of the cavernous sinuses with an extension in the pituitary area (the cavernous sinus cannot be operated and the pituitary gland being glued to the meningioma), and even to the protons, a certain dose is distributed on the pituitary gland, so you have to be followed at the endocrinian plan (1 to 2 times a year maximum) and rather in a specialized hospital service.
For the rest, there is no need to fear burns of the optic nerve, nor chiasma, when it is made by a good radiotherapist.
Latest tips:
1- Take into account the experience of the radiotherapist and the team. It's a good sign when a specialist also tells you his limits
2 – It is justified to request a 2nd opinion. A 3rd opinion possibly but not beyond, otherwise we may be completely lost.
3- For comparative reports and analyzes of MRIs , the most competent centers make a volumetric analysis (in mm 3 or cm 3 ). So when you pass an MRI, you have to ask for an analysis at least in two dimensions (transverse and sagittal/coronal axis), and if possible volumetric (in the 3 axes), especially if the predictable monitoring is over several years.
To find out more about Dr Frédéric Dhermain: https://www.gustaverssy.fr/fr/fredic-dhermain
