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Radiation therapy in head and neck cancer
1. Moderator- Dr. Suja Sreedharan
Dr. Sourjya Banerjee
Presenter- Dr. Sreenivas Kamath
2. 1. Introduction
2. History of radiation
3. Basics of radiation biology
4. Role in H&N Ca
5. Methods of administration
6. Complications
7. Summary
8. Reference
3. Radiation oncology is a medical specialty predominantly focused on the
treatment of neoplastic diseases with the use of ionization radiation
Considerable inroads in radiation treatment planning and delivery
techniques have been made in the last decade toward improving the
practice and changing the philosophy of H&N radiation oncology
4. Wilhelm Conrad Röntgen
German physicist
08 NOV 1985- Xray
Nobel prize 1901
Professor Leopold Freund
Austrian
1897- X-ray in Hairy Mole
Father of Medical radiology
and radiotherapy
Marie Skłodowska Curie
Polish
1898- Radium discovery
Nobel prize 1903, 1911
5. 1905-1920- RT in single
High dose administration
1920- Fractionated
therapy
Studies from sterilisation of
animal testes.
1950- SRS
1990- CRT and IMRT
6. Definition- “the emission of energy as electromagnetic waves or as
moving subatomic particles, especially high-energy particles which
cause ionization”.
Radiation used in radiation therapy have the capacity to produce
excitation or ionisation
Excitation Ionization
7. Ability to release large amounts of energy
locally, resulting in the breaking of chemical
bonds, consequentially producing a large
biologic effect for a relatively small total
amount of energy consumed
8. Depending on the mechanism of action
Directly ionizing radiation- Charged particle
Indirectly ionizing radiation- Neutral particles
Depending on the physical property
Electromagnetic radiation – High energy X rays, γ rays
Particle radiation- Electrons, Protons, Neutrons.
9. Indirectly ionising
X ray and γ rays
X rays – Extranuclear origin- LINAC
γ rays- Intranuclear origin- Radioactive particle
Energy of rays expressed in Mega Volts (MeV)
Spectrum of energy produced with max Value used for reference.
10. Electron, Neutron, Proton, High energy heavy charged particle.
More used- Favourable depth-dose distribution
Electron and proton are more used in radiotherapy
11. Electrons are light, negatively charged particles - linacs
The higher the energy of the electron beam, the more deeply it
penetrates tissue
Protons are 1835 times heavier- Cyclotron/ Synchrotron
Due to mass have less scattering- focused radiation distribution
Bragg Peak effect- Maximum dose at particular distance then steep fall.
12.
13. Fate of irradiated cells
Effect of radiation on normal tissue
Killing effect of radiation
Radiation effect on cellular kinetics
Cell survival and dose response curve
Fractionation
Factors effecting radio sensitivity
14. Produce variety of biological and molecular effects- tumor killing or
normal cell toxicity
The effect depends on various factor.
Cells undego serveral process-
Delay in division G2-M arrest
Apoptosis
Reproductive failure
Genomic instability, mutation, transformation, bystander effects,
adaptive responses.
15. Primary target is DNA
DNA damage can be due to direct effect or due to indirect effect by
reactive free radicals
Can be single stranded or double stranded break
Single stranded damage are more frequent and easier to repair
Double stranded are rare- repair is complex and has molecular effects.
16. Mostly tolerate the radiation exposure
Tissue injury can occur if critical number of clonogenic cell are killed.
Classified based on the time of onset
Acute
Subacute
Chronic
17. Described as following
Lethal damage- Irreversible and irrerepairable
Sublethal damage- can be repaired if given time
Potentially lethal damage- lethal only in certain situations.
Cell death- Reproductive failure or apoptosis
18.
19. Along with the lethal effect radiation may also effect certain processes
that are essential for normal cell functioning
Still under investigation
CDKs, P21, P27, Cyclins.
20. Graphical representation of the cell survival after radiation exposure.
Helped to show the benefit of fractionation
Use of Linear- Quadrantic model
Two components
Alpha (α) Linear component
Beta (β)- Quadrantic component
21. αD- cell death propotional to dose (D)
βD2 – Propotional to the square of Dose (D)
The survival fraction (S) to a given dose (D)
S(D) = e–αD– βD2,
α/β – clinically important
Early responder- high (9-12)
Late responders- low (2-4)
22. Since 20th centuary fractionation has replaced the single dose
radiotherapy
1900- Study by Regaud- Ram sterilisation
Single dose of radiation could not cause sterilisation- more skin
necrosis
Series of smaller dose could sterilze and had lesser skin necrosis
24. Repair of sub-lethal damage-
Capacity to repair depends on the type of tissue- Mature cells with less
turn over
Avoid injury to the late responding tissue.
Reassortment
Cell cycle are usually asynchronous. Cells in G2-M phase are killed
Those that escaped will progress with cycle and reach more sensitive phase.
More effective for tumors since they have high turn over
4R
25. Repopulation
When the tumor cells are depleted by either surgical or CTRT- There is a
regenerative response
Accelerated population of the tumor cells
Hence fractionation provides with better loco regional control
Reoxygenation
Due to tumor shrinkage with treatment the tumor cells which were far from the
feeding artery comes closer. (50-75Mm)
Hypoxic tumor micro environment oxygenated
More sensitive to subsequent radiation
4R
26.
27. Fractionation Studies 5 year
survival
5 year
locoregional
Hyperfractionation EORTC 22791,
RTOG9003, RIO
36.7/28.5 57.9/48.5
Accelerated
Fractionation with dose
EORTC 22851,
RTOG 9003,
DAHANCA
44.4/42.4 47.4/40.2
The primary tumor sites were oropharynx and larynx, with the majority of patients having intermediate
to locally advanced H&N cancers
28. Reduce radiosensitivity Increase Radiosensitivity
Hypoxic state- Post operative scared tissue.
Tissue hypoxia.
Chemical radical scavengers
Low dose rate/ Hyperfractionation of RT High dose rate/ Single fraction
Physical factors- LET, relative biological
effectiveness (RBE), and fraction and
protraction
High LET radiation.
Cell cycle phase Late S phase Cell cycle phase- G2 M
29. Indication of RT in Head and neck cancers
Curative RT- Oral/ oropharyngeal SCC, Nasopharynx, early laryngeal,
superficial skin cancers.
Adjuvant- PORT (post operative radiotherapy)
Palliative RT
31. Different methods of administration
Newer high precision RT delivery system
Approach to patient for RT
32. The radiotherapy can be administered as
Teletherapy
Brachytherapy
Stereotactic radiosurgery
33. Teletherapy refers to radiation therapy given by an external radiation
source at a distance from the body
Most commonly used
Conventional fractionation used
1.8-2Gy per day. 5 days a week. For 6-7 weeks (total dose of 66-
72Gy)
34. Radioisotopes are placed to tumor bed using specialised devices
Can be permanent or temporary placement
Often used for recurrent tumors
The depth of radiation is very less and only tumor bed gets radiated.
35. Low dose rate- upto 2Gy per hour
High dose rate- 12Gy per hour (temporary)
Commonly used for
Lip, floor of mouth, oral tongue, base of tongue, buccal mucosa,
tonsillar region, nasopharynx, skull base, and neck.
T1, T2 lesion of tongue can be treated with only Brachy therapy.
36.
37. Developed during 1950-60 Takahashi Japan
Conforming radiation doses to irregular tumor volumes
Reduce radiation dose to critical normal structures nearby the tumor
without compromising dose delivery to the intended target
38. highly sophisticated application of CRT
Modifies the intensity of photon beams to provide greater flexibility and
precision in treating irregular tumor targets resulting in a sharper dose-fall off
gradient, concave dose distribution, and narrower treatment margins
Requires proper planning and pre-treatment delineation of the tumor volume
and extent.
CT, MRI, PET Scan
39. Target volumes are dose painted and subclinical areas are painted with
lesser dose
Results are almost at par with conventional RT
Improve xerostomia, and swallowing function.
Used advanced computer planning and Multileaf collimator
Previously used the Dynamic rotational technique or Step and shoot
technique.
Now Volumetric modulated arc therapy (VMAT)- radiation delivered 360
degrees
40. Use of two-dimensional and three-dimensional imaging during the
course of treatment to account for setup uncertainties and patient
positioning on the treatment table and ensure accurate placement of
the radiation field according to the initial radiation treatment plan
41. Changing of radiotherapy plans during treatment course to reoptimize
based on the changes in the tumor volume during treatment
Patient factor- tumor shrinkage, weight loss, internal target motion, or
changes in tumor biology or function such as hypoxia.
Technical factor- positioning accuracy or daily organ motion are the
center of attention
Immobilization devices and daily onboard imaging to verify patient
positioning. Adding 3–5 mm planning target volume (PTV) margin
42.
43. Stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT)
are techniques to administer precisely directed, high-dose irradiation
that tightly conforms to an intracranial target
Gamma Knife, modified LINAC radiosurgery systems (including
CyberKnife and image-guided radiotherapy systems), TomoTherapy, or
proton beam systems.
44. Veteran Affair (VA) larynx préservation trial in 1991
Meta-Analysis of Chemotherapy on Head and Neck Cancer (MACHNC)
1. Induction chemotherapy
2. Adjuvant radiotherapy and chemotherapy
3. Altered fractionation with concurrent chemotherapy
45. Cetuximab – antiEGFR monoclonal antibody
Geftinib and erlotinib are currently being studied
46. Biomarkers
EBV DNA titres in NPC
HPV and orophanryngeal cancer
EGFR expression in the HNSCC
47. Used for symptomatic relief of tumor burdern in patient with incurable
disease
Conventional regimen- 30 Gy given in 10 fractions over 2 weeks
Provides around 65% of symptomatic relief in ¾ of cases
Hypofractionation has been used to reduce the treatment duration
50. Comprehensive evaluation
Carious teeth that are not salvageable should be extracted
Significant number of dental fillings- Personalised mouth guard
Fluoride prophylaxis
Hypothyroidism- evaluation and appropriate management
Hematocrit level- more than 30%
Ophthalmologic evaluation
Nutritonal assessment, SLT counselling
51. Patient Education
Rationale for treatment
Expected toxicities of treatment
Process of treatment planning
Rough time frame for starting treatment
52. Patient treatment position, immobilization, and planning imaging
Delineation of tumor/target volumes and organs at risk
Dose prescription
Plan evaluation and improvement
Plan implementation and treatment verification
53. First step in setting up the radiation fields.
CT / X ray imaging
Conventional
3D CRT/ IMRT- Volume delineation
54. Get patient in optimal / acceptable treatment position
Allows reproducible and verifiable treatment of tumour
Possible additional benefit: allows / increases sparing of normal tissues
Patient comfort is critical
Pain control
Use support devices and immobilization devices liberally
Can patient maintain desired position for 15 – 30 minutes without
difficulty?
For a given site, avoid treating same patient in different positions
55. Gross tumour volume (GTV) is outlined
A margin is included around the GTV to include areas at risk for
microscopic involvement, this is the clinical target volume (CTV)
A margin is added onto the CTV to allow for differences in internal
organ motion or day-today set up variations, this is the planning target
volume (PTV)
There is a margin added to the PTV to allow for physical characteristics
of the beam (penumbra), this is the actual treatment volume
56.
57.
58.
59. Weekly status check of patients undergoing radiation therapy
sore mouth or throat, dysphagia, hoarseness, altered taste, xerostomia, skin reactions, and
ear symptoms
Complete examination- Tumor and complications
The general condition, body weight, and complete blood cell count should be
monitored
60. Organs At Risk
Class I organs : radiation lesions are fatal or result in severe
morbidity (spinal cord)
Class II organs : radiation lesions result in mild to moderate morbidity
(bowel)
Class III organs : radiation lesions are mild, transient and reversible,
or result in no significant morbidity (muscle)
61. Acute-during or shortly after radiation
Late- 3 months after the completion of treatment to lifetime
Acute injury is related to toxic effects of radiation treatment on rapidly dividing
cells, whereas late injury manifests itself in slowly dividing tissues such as
connective and neural tissues
Concurrent use of chemotherapy- increases the frequency and severity of
radiation related sequelae
62. RTOG -toxicity scoring system
0 to 4, with 0 having no change over baseline and 4 being severe. For
example, in the case of skin, grade 4 is ulceration, hemorrhage, and
necrosis
63.
64. Acute Sequelae
Affects mucous membranes, skin, and salivary tissues.
Basal proliferating layer in the epidermis
Lower levels of exposure to the basal layer- erythema and hyperpigmentation of
the skin
Erythema and
hyperpigmentation
Dry squamation,
peeling and
scaling
Wet desquamation
Slough off and
expose dermis
Skin moisturizers and antiseptic creams
65. Mucus membranes -dose-dependent acute toxicity
At lower doses, mucosal erythema develops, which progresses to
pseudomembranous-like mucositis
Erythema,
Pseudomembrane
Confluent and
ulcerate
Soft tissue
necrosis,
laryngeal edema,
serous otits media
66. Salivary tissues are exquisitely sensitive -change in the volume and
composition of saliva
The viscosity of saliva is increased - dryness of the mucous
membranes and the formation of crusts.
These areas can be a nidus for infection and should be addressed with
oral irrigation with use of a solution that contains baking soda and salt
Alteration in taste occurs as a result of the direct effect on taste buds,
as do changes in the biochemical composition of saliva.
Bland and metallic taste
Sense of taste spontaneously recovers over time.
67. Acute radiation sequelae can severely impair oral intake of regular food
Dietary modification and nutritional supplements must be provided
Nasogastric or gastrostomy tube feeding should be considered as a last
resort
Analgesic drugs, steroids, and antifungal medications also may be
required to alleviate acute manifestations of radiation mucositis
68. Late Sequelae
A combination of vascular endothelial damage, fibrosis from scarring,
and muscle atrophy along with death of the parenchymal cellular
network
Skin-atrophy and the development of telangiectasias
Subdermal fibrosis and contracture
Skin carcinomas
69. Surgical procedures in previously irradiated fields have an inherent risk
of delayed healing and/or skin and soft tissue necrosis
Surgical planning should include excision of heavily irradiated skin and
reconstruction of the surgical defect with non irradiated vascularized
tissue.
70. Xerostomia -difficulty in swallowing and increased risk of dental caries.
Affects the patient's quality of life
At present, no therapeutic agents are available to effectively treat
xerostomia
Prevention of xerostomia
Amifostine
Regular, frequent oral irrigation with a weak solution of salt and
sodium bicarbonate
High humidity in inhaled air, particularly during the winter when the
heating of rooms
71. Continued dental care- to minimize the development of caries and the
risk of osteoradionecrosis
Hyperbaric oxygen-prevention of radionecrosis. No benefit once the
bone has already become necrotic.
72. Thyroid function tests including TSH-all patients who have been treated
with radiation in the central compartment of the neck
Biochemical hypothyroidism is observed in a significant number of
patients
Thyroid hormone replacement therapy is started if the TSH level rises
above the normal range, irrespective of the T3 and T4 values, which
may be within normal limits
If the hypothalamic–pituitary axis has been exposed to radiation, a
complete endocrine screening should be obtained.
73. Fibrosis and muscle atrophy can lead to development of motor
dysfunction, contracture, and strictures
Pharyngo-esophageal stricture - repeated dilatations , surgical
reconstruction
Fibrosis of the muscles of mastication - trismus
No effective treatment
Prevention with jaw-stretching active and passive exercises instituted
soon after the completion of therapy and continued until satisfactory
jaw opening is achieved
Post radiation fibrosis and scarring also may hamper shoulder
movement- daily range of motion exercises for the neck and shoulders to
prevent
74. Cartilage and bone-impairment of growth in children, atrophy, and
occasionally radiation chondritis or osteonecrosis
Radiation necrosis of the larynx
0.1% to 0.5% risk of a radiation-induced second cancer in the irradiated
field
These second tumors typically are squamous cell carcinomas of the
skin and high-grade sarcomas that may be difficult to treat
The risk for development of radiation-induced cancers increases with
time
75. L’hermitte syndrome may develop in some patients whose cervical spinal cord
is exposed to radiation
Symmetrical shooting pain like an electrical shock radiating down the spine
and extremities with flexion of the neck
Benign, self-limiting myelopathy
Due to demyelination1
1 to 3 months after radiation therapy and can last for up to 9 months or more
If these symptoms develop for the first time 9 to 12 months after radiation
therapy, the more likely diagnosis is radiation myelitis, which is a more serious
problem.
76. The field of H&N radiation oncology has been exciting and rewarding in the
past few decades
Recent advances in radiation oncology have generated a great deal of
optimism as novel strategies for improving quality of life and survival rates are
being developed for clinical testing
Better radiobiologic insight to help identify new molecular targets for
selectively sensitizing tumor to radiation and thus improve upon the
therapeutic ratio
Hinweis der Redaktion
Volume delineation for external beam and sealed sources • The gross tumour volume (GTV) is outlined • A margin is included around the GTV to include areas at risk for microscopic involvement, this is the clinical target volume (CTV) • A margin is added onto the CTV to allow for differences in internal organ motion or day-today set up variations, this is the planning target volume (PTV) • There is a margin added to the PTV to allow for physical characteristics of the beam (penumbra), this is the actual treatment volume.
International commission on radiation units and measurements