Radiotherapy treatment for cancer
Introduction
External or transcutaneous radiotherapy which uses a radiation source placed at a distance from the irradiated tissues, and the irradiation of healthy tissues located in the path of the beams cannot be avoided.
- Conformal radiotherapy :
Targets the tumor in all 3 spatial directions while avoiding radiation damage to healthy tissues and organs surrounding the tumor.
- Intensity-modulated radiotherapy
IMRT is a 3D conformal radiotherapy in which the fluence (quantity of photons per unit area) of the beams is modulated during the session.
- Proton therapy
Allows ultra-targeted targeting of tumors close to fragile organs such as the brain or spinal cord.
- Brachytherapy
Consists of placing radioactive sources directly in contact with the tumor.
- Indications
- Curative:
- Small tumors, radiosensitive or inoperable tumors.
- Local recurrence, lymph node metastases.
- Palliative:
- Large tumors
- Inoperable patients (general problem)
- Basic concepts
- Dosimetry
Study of the doses received by the different points of the irradiated volumes. Expressed in Grays (Gy).
- Target volume
Corresponds to the tumor volume to be reached by the rays in the same position in order to control the regression of the tumor and limit the after-effects on the surrounding tissues.
- Irradiation fields
In the case of VADS tumors, these include:
- The salivary glands
- The jaws
- The teeth
- The lymph node areas
Radiotherapy treatment for cancer
CB TUMORS: Jaws, Teeth and Salivary Glands
Radiotherapy treatment for cancer
OROPHARYNX TUMORS: Parotids, Submaxillary and Posterior Teeth
Radiotherapy treatment for cancer
CAVUM TUMORS: Similar to those of the oropharynx with higher extension.
Radiotherapy treatment for cancer
LARYNX TUMORS: Parotids and retropharyngeal lymph nodes
Radiotherapy treatment for cancer
TUMORS OF THE HYPOPHARYNX: Parotids and sometimes submax.
- Lymph node irradiation:
- Roots of M and PM <
- HODGKIN’S DISEASE:
- Salivary glands
- ½ roots <
- Tooth germs <
- Complications and aftereffects
- Acute complications
- Complications involving the skin covering
- From the 3rd week, at 20Gys.
- Pigmentation, epidermatitis, pruritus of the irradiated area
- Hair loss.
- Repair 6 weeks after stopping TRT.
- The radio is silent
Iatrogenic, painful stomatitis induced by ionizing radiation.
Functional signs: pain, dysphagia, speech disorder.
Time to onset: 10 to 15 days after the start of TRT.
Duration: Persists 2-3 weeks after TRT ends.
Physiopathology: Mucositis is a complex biological process
We describe 4 phases:
– inflammatory phase (vascular)
– epithelial phase
– ulcerative phase
– remission phase
Risk factors:
- Dose and duration of irradiation
- Hyposialia
- The bad HBD
- Smoking
Mucositis assessment:
- Degree 0 : no alteration
- Grade 1 : dysesthesia, erythema
- Grade 2 : erythema, ulceration, solid food possible
- Grade 3 : ulceration, liquid diet only.
- Grade 4 : No power supply possible.
Evolution :
- Complete recovery 2 to 3 weeks after TRT
- Rarely, chronic ulcerations, necrosis with exposure of the underlying bone.
- Mucosal necrosis
May appear after ulceration (irradiation) or on healthy mucosa.
Appears between 2 months and 1 year after the Rx.
May be promoted by: local trauma or smoking
It could be the start of an ORN.
- Mucous candidiasis
Qlt, Qtt changes in saliva
↓
Decrease in PH
↓
Development of acidogenic flora
↓
Bacterial and candidal infections
- Taste disorders “Ageusia”
- Disturbance of taste function
- Settles from the 2nd or 3rd week
- From 30 Gys.
- Irradiation of sensory receptors of the mucosa
- Metallic taste sensation
- Regression 4 to 6 weeks after the end of TRT.
- Salivary complications “Hyposialy”
- Consequence of irradiation of the salivary glands
- From 50 to 70 Gys → viscous saliva, acidic pH
- Dry mouth → functional difficulties
- Hyposialia can be transient or permanent (xerostomia).
- Late effects
- Muscle complications: LOB
It is due to 2 causes:
* Fibrosis of the masticatory muscles
* ATM irradiation
Occurs after 3 to 6 months.
Power disruption,
brushing and prosthetic realization.
- Consequences on the dental organ
- Brownish or black discoloration of the enamel-dentin surfaces
- Aggressiveness
- Speed of evolution
- Xerostomia
- Consequence of salivary gland atrophy
- Definitive from 65 Gys.
- Dry mouth.
- Speech and swallowing problems.
- Oral infections and cavities.
- Bone complications: ORN
Definition:
This is an iatrogenic osteitis which appears at doses of ionizing radiation = or > 40 Gys.
It is observed especially at the level of the mandible.
Pathogenesis:
- Theory 2I: Ischemia , Infection .
- Theory 3H: Hypovascularity , Hypoxia , Hypocellularity .
Etiological factors
- Determining factors: radiotherapy (> 60Gys)
- Triggering factors: trauma.
- Favoring factors: large tumor volume, bone proximity.
Clinical aspects:
- Aseptic ORN: asymptomatic.
- Septic ORN: superinfection of the bone.
Classification:
- Stage 1: asymptomatic, bone denudation, no fracture
- Stage 2: moderate symptoms, with or without fracture.
- Stage 3: severe symptoms, fistulas, fracture and sequestrum.
Rx Aspects:
- Bone rarefaction , osteolysis.
- Sequestration image
Evolution:
Extension, superinfection, fistulas, pathological fractures.
- Periodontal diseases:
Decreased vascularity
Increased plaque buildup
Periodontal diseases
- Submental edema:
Consequence of irradiation of the lymph nodes
- Complications in children
- The same after-effects as in adults.
- Growth disorders
- Disruption of tooth development .
- Micrognathia
- Microdonthia, agenesis.
- Enamel hypoplasia.
- Muscular sclerosis → temporomandibular ankylosis
- Cavities, candidiasis.
- Precautions to take when undergoing radiotherapy
Before
- ROLE OF THE DENTIST:
- Make an initial assessment of the oral health.
- Assess the patient’s level of motivation.
- Perform a MECB.
- Implement certain prophylactic acts.
- CB RESTORATION:
- Motivation for hygiene.
- Tooth extractions.
- Evaluation in conservative dentistry .
- Preventive laser therapy.
- Production of fluoride gel gutter
During
- ROLE OF THE DENTIST:
- Relieve the patient.
- Intercept or control bacterial or candidal infection.
- Maintain good oral health.
- Manage the emergency.
- Motivation for HBD: soft toothbrush.
- Local care: BDB
- General TRT: ATB, analgesics, antifungals.
- Curative laser therapy.
- Removal of prostheses.
- Mandibular mobilization.
- Extract if necessary.
- Check the HBD.
- Check fluoro prophylaxis.
- Check for cavities and fillings
After
- CONTROLLING SALIVARY DEFICIENCY:
- Use of saliva substitutes:
- Artificial saliva.
- Salivary prosthesis.
- Others: oil, butter, chewing gum.
- Prescription of sialagogues.
- FIGHTING THE LOB:
- Massages.
- Mandibular mobilization .
- Facial expressions exercises.
- EXTRACTIONS:
- In the irradiation field:
– Exo after 6 months.
- Radiotherapist’s agreement
- ATB coverage 2 days before → healing.
- Anesthesia without vasoconstrictor
- Sutures.
- Outside the irradiation field:
The patient is considered healthy.
- PROSTHESIS:
- Carried out after the disappearance of any reaction phenomenon of the mucosa.
- Joint prosthesis: motivated patient, widely dentated.
- Adjunct prosthesis:
- Non-compressive imprint.
- Occlusion of convenience.
- Resin teeth.
- Periodic checks.
- ORN SURGICAL TRT:
- Intended for severe forms.
- Limited surgery: sequestration.
- Wide surgery: hemi mandibulectomy .
- Flap surgery.
- Hyperbaric oxygen therapy:
– Stimulation of collagen synthesis at bone level.
- IRRADIATED CHILD:
- Monitoring and evaluation of HBD.
- Extractions and care are carried out with the same precautions as for adults.
- Difficult but essential prosthesis.
- TRT ODF.