this presentation describes how radiation effects normal structures in head and neck region and about the late and acute toxicities which may occur if the radiation exceeds tolerance dose as per QUANTEC

1. SIDE EFFECTS OF
RADIATION IN HEAD AND
NECK CANCERS
ANAGHA S PACHAT
INTERN
MSc RADIATION PHYSICS

2. introduction
• Radiation therapy is an integral part of the treatment of patients
inflicted with cancer.
• It is estimated that over 60% of patients with cancer will have
radiotherapy as part of their total course of treatment .
• Radiation therapy affects both tumor cells and uninvolved normal
cells; the former to the benefit and the later to the detriment of
patients.
• With the goal of achieving uncomplicated local regional control of
cancer, balancing between the two is both an art and a science of
radiation oncology

3. • From a historical point of view, the first formal attempt to
address the goal, namely normal tissue tolerance to radiation,
was carried out by Rubin and Cassarett. This was purely
empirical.
• In 1991, investigators pooled their clinical experience,
judgment, and information regarding partial organ tolerance
doses and produced the “Emami paper”.
• During the 1990s and 2000s, a large number of studies related
dose–volume data to clinical outcomes. The QUANTEC review
was an attempt to refine the guidelines based on the available
3D dose/volume/outcome data

4. Effects of radiation on cells
• Radiation damage cell by two methods
 DIRECT ACTION
Exposure to ionizing radiation
causes direct DNA damage through linear energy
transfer
 INDIRECT ACTION
indirect damage by radiolytic
cleavage of water, yielding hydroxyl radicals capable
of abstracting hydrogen from the backbone of DNA
to cause double-stranded breaks

6. Deterministic Effects
• Deterministic effects are characterized by:
 A threshold dose below which no effect is seen
 Worsening of the effect as dose increases over the threshold
 Always occurring once the threshold dose is reached
 Different effects, tissues and people have different threshold doses
for deterministic effects
• All early effects, and most normal tissue late effects are
deterministic.

7. •Stochastic Effects
 Stochastic effects account for the remaining late
effects:
 They have no threshold dose
 They increase in likelihood as dose increase
 Their severity is not dose related
 There is no dose above which stochastic effects are
certain to occur
• Stochastic effects include radiation
carcinogenesis and hereditary effects

8. Head and neck cancers

9. Normal tissue tolerance dose as per
QUANTEC
• Parotid glands mean <25Gy(both glands) or mean
<20Gy (one gland)
• Submandibular glands mean <35Gy
• Larynx mean<44 Gy, v30<27% max 63 -66 Gy
• Mandible max 70 GY if not possible V75<1cc
• Oral cavity non oral cavity cancer mean<30Gy avoid
hotspots >60Gy
oral cavity cancer mean<30 Gy V55<icc max
65Gy
• Esophagus V45<33%
• Pharyngeal constrictor mean<50Gy
• Thyroid V26<20%

10. Radiation Side Effects
• Acute Side Effects
• Acute reactions that can occur during irradiation are
predictable toxicities,
• depend on the dose and schedule of radiation therapy
used
• Such effects include mucositis, odynophagia, dysphagia,
hoarseness, xerostomia, dermatitis, and weight loss.
• These effects occur to some degree in the majority of
patients, but they are self-limited in duration.

11. Dermatitis
• Radiation damage to stem cells in basal layers of the skin can give rise
to a sunburn-like desquamation.
• These effects can occur as early as 2 weeks after the start of
radiotherapy.
• This side effect can be minimized through appropriate skin care,
avoidance of exposure to potential chemical irritants, limitation of
direct sun exposure, and avoiding application of lotions, ointments, or
fragrances to the head and neck region
• IMRT typically worsens skin reaction because of the multiple
target beams, but this effect can be reduced by specifying the
skin as an avoidance structure and by treating the lower neck
with an anterior beam rather than including it in the IMRT
plan

13. Xerostomia—
• The severity of xerostomia resulting from RT for HNC
depends on the volume of salivary tissue irradiated.
• Temporary loss of saliva is significant after about 10 Gy is
delivered to the salivary glands,
• administration of doses significantly higher than 26 Gy
can cause permanent loss of function.
• Alteration in taste can also occur,
• decreased oral intake may contribute to reduced saliva
production.
• Prevention of this side effect can be performed by reducing
salivary gland dosage in formal planning.

14. Mucositis
• Radiation-induced loss of stem cells in the basal layer
interferes with the replacement of cells in the superficial
mucosal layers when they are lost through normal
physiologic sloughing.
• The subsequent denuding of the epithelium results in
mucositis, which can be painful and can interfere with
food intake and nutrition.
• Mucositis usually develops 2 to 3 weeks after the start of
RT.
• The incidence of mucositis is variable, depending on the
field, the total dose and duration of RT

15. Late Toxicities
• Radiation effects that occur months, years, or
even decades after irradiation, called late
effects. “Consequential late effects” result from
the host's reaction to severe acute toxicity.
Certain organs are more prone to late toxicity

16. Xerostomia
A dry mouth or xerostomia is one of the most common
complications during and after radiotherapy for head and neck
cancer
Radiation-induced xerostomia consists in the chronic dryness of
the mouth caused by parotid gland irradiation. Parotid glands
produce approximately 60% of saliva while the rest is secreted by
submandibular and accessory salivary glands
since irreparable damage is caused to the salivary glands, which
are included in the radiation fields. Xerostomia not only
significantly impairs the quality of life of potentially cured cancer
patients, it may also lead to severe and long-term oral disorders

17. Xerostomia is a frustrating side effect that may lead to many
other effects. It often improves with time, but it can be long-
lasting or even permanent.
The threshold dose for development of xerostomia was
described before in the range of 10 to 25.8 gy
• Regarding treatment, several strategies may minimize the
incidence of xerostomia. When possible, sparing one parotid
gland and, if possible, the submandibular glands can
greatly diminish the incidence of xerostomia.

18. Osteoradionecrosis
• The Osteoradionecrosis (ORN) of the jaw is a severe
complication of RT for HNC.
• Osteoradionecrosis (ORN) is a condition of nonvital
bone in a site of radiation injury. ORN can be
spontaneous, but it most commonly results from
tissue injury.
• Depending on the location and extent of the lesion,
symptoms can include pain, bad breath, dysgeusia,
trismus, difficulty with mastication, deglutition,
and/or speech, fistula formation, pathologic fracture,
and local, spreading, or systemic infection.

19. • mandible is the most commonly affected bone,
because in the majority of patients undergoing
treatment for HNC, a large part of it is inevitably
exposed to high RT doses.
• It has been shown that increasing the external
beam radiation dose above 50 Gray gives a
significantly increased risk for developing
osteoradionecrosis

20. Effects on hearing
• Radiotherapy can result in cochlear damage, with sensorineural
hearing loss (SNHL) occurring in about 25% of patients treated
with doses approaching 60 Gy,
• SNHL has been considered infrequent at lower radiation therapy
doses
• Data suggest that cochlear doses of 30 to 50 Gy can cause
intermediate frequency SNHL,
• . Emerging data on adults treated for head and neck cancer also
suggest that doses of >45 Gy impair hearing, particularly in the
higher frequencies

21. Effects on eye
• Radiotherapy can affect the retina, lens, conjunctiva, lacrimal
apparatus, optic nerve, and lid.
• Patient may develop dry eye, cataract, orbital hypoplasia, ptosis,
retinopathy, keratoconjunctivitis, optic neuropathy, lid epithelioma,
and impairment of vision, following doses of 30 to 65 Gy.
• the higher dose ranges (>50 Gy) are associated with lid epitheliomas,
keratoconjunctivitis, lacrimal duct atrophy, and severe dry eye.
• Retinitis and optic neuropathy may also occur following doses of 50 to
65 Gy, and even at lower total doses if the individual fraction size is >2
Gy .
• Cataracts are reported following lower doses of 10 to 18 Gy

22. fibrosis
• A serious complication of RT in the treatment of cancer
patients is the late-onset of fibrosis in normal tissues,
including the neck, pharynx, esophagus, and
temporomandibular joint.
• Radiation-induced fibrosis (RIF) is similar to
inflammation, wound healing, and fibrosis of any origin
• .

23. • RIF can cause a wide range of clinical manifestations, including
cutaneous induration, lymphedema, restrictions in joint motion,
strictures and stenoses in hollow organs, and ulcerations.
• Specifically in the head and neck region it may cause trismus,
which can progress over time.
• RIF in the esophagus and hypopharynx may lead to strictures,
ulcerations, and fistula formation.
• Radiation fibrosis to the constrictor muscles may lead to
chronic dysphagia. The best way to prevent this side effect is
conformal planning to spare unnecessary radiation.

24. • The risk of radiation-induced fibrosis is
increased with higher radiation doses and larger
treated volumes . The radiation dose that causes
fibrosis can vary substantially in different
tissues
• ●Fibrosis in both connective and vascular tissues
is generally associated with total radiation doses
of 60 Gy or higher.

25. Thyroid Dysfunction
• Hypothyroidism or hyperthyroidism can develop after
radiotherapy.
• Hyperthyroidism is characterized by heat intolerance, weight
loss, insomnia, increased appetite, diarrhea, moist skin,,
nervousness, tremors, exophthalmus, and goiter. Thyroid
enlargement, and more frequently, thyroid nodularity, can also
develop.
• . Hypo- or hyperthyroidism results from fractionated radiation
>20 Gy to the neck or cervical spine, or >7.5 Gy of TBI. Thyroid
nodularity can occur after lower dose exposure

26. • RT-induced hypothyroidism develops at a median
of 1.4 to 1.8 years after RT
• It is more common in patients undergoing both
neck surgery and RT than in those who have RT
alone.

27. Vascular Complications
• Carotid artery rupture (also called carotid blowout syndrome) and
oropharyngo cutaneous fistula are major complications associated with
RT to the neck. These sequelae occur almost exclusively in patients
who have received combined surgery and RT.

28. Conclusion
• With the use of megavoltage radiation ,
careful radiotherapy planning and techniques
with the aid of dedicated computers, better
understanding of radiobiology , tolerance of
normal tissues and organs and improvement
of other surgical technology major
complications occur less frequently in modern
practice radiation therapy

29. Thankyou