4. Dysphagia: swallowing impairment and can result in penetration or aspiration
into the airway
Causes:
Mechanical Congenital abnormalities, head & neck tumors, oral pathology,
stenosis, diverticula, xerostomia
Infection Inflammation, ulceration, neurological dysfunction
Iatrogenic/Post
treatment
Post-surgery, Medications, Radiation induced
Neurological Decreased consciousness, dementia, CVA, trauma, CNS tumors
Neuromuscular Ageing, myasthenia gravis, critical illness, sepsis, myopathies
5. Radiation Therapy
◦ Radiation Therapy (RT)- pivotal role in the definitive, postoperative and palliative treatment of
HNC
◦ Majority of all HNC patients will receive RT at least once during the course of their disease
◦ RT affects both tumor cells and uninvolved normal cells; the former to the benefit and the later
to the detriment of patients
◦ Goal- balancing between these two is an art and a science of radiation oncology
6. Dysphagia in Head & Neck Cancer
◦ Pretreatment:- 14-18% of HNC pts
1. Obstruction by tumour volume
2. Infiltration of structures involved in swallowing
3. Prior Surgery
(Molen et al, BMC Ear, Nose and Throat Disorders 2009)
7. Radiation induced dysphagia
◦ Acute and long-term complication
◦ Nearly 50 % of patients identifying it as a distressing symptom following radiation treatment
◦ Greater in those treated for curative purposes
◦ Acute dysphagia tends to resolve shortly after treatment
◦ Severity of late dysphagia has been reported to decrease in 32 %, to remain unchanged in 48 %
and to worsen in 20 % , even years after therapy)
J.W.G. Roe et al. / Oral Oncology 50 (2014) 1182–1187
Nguyen et al., Oral Oncology (2006) 42, 374–380
9. Complications of Dysphagia
◦ Aspiration (silent aspiration is frequent in irradiated HNC patients and the cough reflex is
ineffective or absent in almost half of patients)
◦ Aspiration Pneumonia
◦ Dietary modifications
◦ Nutritional deficiencies
◦ Prolonged feeding tube dependence
◦ Poor social interactions & lifestyle alterations
◦ Degradation in QOL
10. RTOG Radiation Toxicity
Grade 1 2 3 4
Pharynx &
esophagus
Mild dysphagia or
odynophagia / may require
topical anesthetic or non-
narcotic analgesics / may
require soft diet
Moderate dysphagia or
odynophagia / may
require narcotic
analgesics / may
require puree or liquid
diet
Severe dysphagia or
odynophagia with
dehydration or weight loss >
15% from pretreatment
baseline requiring NG
feeding tube, IV fluids, or
hyperalimentation
Complete obstruction,
ulceration, perforation,
fistula
11. Improving RT in HNC
1.Three-Dimensional Conformal Radiation
2.Acceleration of Radiation Dose
3.Intensity Modulated Radiation Therapy
4.Radiosensitizers
5.Radiation Protectors
12. The first step required is to identify the anatomic structures whose damage or
malfunction after intensive therapy caused dysphagia and aspiration.
Dysphagia aspiration structures(DARSs)
◦ Anatomical structures that are critical to the swallowing function
◦ Radiation dose delivery to these structures (DARSs), shown to predict
swallowing outcome
Dysphagia-optimized IMRT (Do-IMRT)
◦ Preferential sparing of key swallowing structures implicated in post-radiation
dysfunction without compromising locoregional control & survival outcomes.
13. Swallowing organs at risk (SWOARs)
SWOARs include the pharyngeal constrictor muscles, the larynx (both the glottic and
supraglottic part), and the upper oesophageal sphincter.
Seven functional swallowing units (FSUs) were defined, associated with:
◦ Hyolaryngeal elevation (HLE)(3)
◦ Tongue base retraction (TBR) (2)
◦ Tongue motion (2)
Functional swallowing units (FSUs)
A. Gawryszuk et al. / Radiotherapy and Oncology 130 (2019) 62–67 65
20. Results:
Anatomic structures whose malfunction was the likely cause of each of these abnormalities, were
the pharyngeal constrictor muscles, the supraglottic larynx, and, glottic larynx. Therefore,
deemed the DARS.
◦ The lowest maximal dose delivered to a stricture volume was 50 Gy.
◦ Reducing the volumes of the DARS receiving >50 Gy (V50) was, therefore, a planning and
evaluation goal.
Dose (V50) reduction of constrictors:
◦ 3D CRT vs. standard (st)IMRT : 10% on average
◦ st IMRT vs. dysphagia optimized (do) IMRT: additional 10%
◦ No difference in D max (due to overlap with PTV)
Dose reduction of larynx (glottic & supraglottic; V50): (larynx or vallecula not involved)
◦ 3D CRT vs. st IMRT: 7% (p-0.054)
◦ st IMRT vs. do IMRT: additional 11%
21. ◦ 10 studies
◦ Reducing the Dmean to the non involved PCM from 61–64 to 52–55 Gy would result in better
MBS scores, less aspiration & better swallowing
◦ If the Dmean for the supraglottic larynx are lowered from 48–54 to 36–38 Gy, the same results
are observed
◦ Conclusion: Dmean to the pharyngeal constrictor muscles appears to be the most important
dosimetric predictor of late swallowing disturbances
22. ◦ 1st prospectively designed cohort study
◦ To develop a predictive model for radiation induced swallowing dysfunction (RISD)
in HNC patients treated with primary curatively intended (CH) RT
◦ Mean doses to the SPC and supraglottic larynx were most predictive of RTOG
grade 2 dysphagia at 6 months after treatment
23. • Phase III multicenter RCT
• Hypothesis: Using Dysphagia-Optimzed IMRT (DO-IMRT) to reduce the dose to
pharyngeal constrictor muscles (PCM) would improve swallowing function
compared to standard IMRT (S-IMRT)
• First randomized study to demonstrate functional benefit of swallow-sparing IMRT
in OPC
24. Inclusion criterea
◦ Aged 18 or above
◦ Pt undergoing radiochemotherapy or
radiotherapy alone for cancers of the
oropharynx or hypopharynx
◦ B/l Neck RT required
◦ Stage T1-4, N0-3, M0 disease
Exclusion Criterea
◦ Preexisting swallowing dysfunction
unrelated to head & neck cancer
◦ Posterior pharyngeal wall, or
retropharyngeal lymph node involvement
◦ Major head & neck surgery (excluding
biopsies/ tonsillectomy)
25.
26. Planning objectives prioritized in the following order:
◦ Critical organ constraints (spinal cord and brainstem)
◦ PTV_6500 coverage
◦ Constrictor constraints
◦ PTV_5400 coverage
◦ Parotid gland constraints
◦ And other non-specified normal tissues
27. Do-IMRT
Aim : To spare the PCM lying outside the high dose CTV
For oropharyngeal primaries,
Mandatory D mean <50 Gy to the volume of SMPCM lying outside CTV
Optimal D mean <20 Gy to the volume of IPCM lying outside CTV_6500
Hypopharyngeal tumors
Mandatory D mean <50 Gy set for IPCM and
Optimal D mean <40 Gy have been set for SMPCM.
28. ◦ Primary endpoint: Difference in the mean MDADI composite score, at 12 months post
treatment
◦ Secondary endpoints: Prospective and longitudinal evaluation of swallow outcomes
incorporating a range of subjective and objective assessments, quality of life measures, LRC &
OS
• Longitudinal pattern of MDADI upto 2years
• UW-QOL
• PSS-HN domain scores
◦ The 100ml water swallow test
◦ Video Fluoroscopy
◦ Acute & late radiation toxicity (CTCAE v4.0 & LENTSOMA)
◦ Locoregional tumour control & Overall Survival
29. Statistical Considerations
◦ Sample size required 102 pts.
To detect a 10 point improvement in MDADI composite score with DO-IMRT vs S-IMRT
Assuming mean MDADI composite scores 72 (SD=13.8) with S-IMRT
90% power, 2 sided 5% significance level allowance for 20% non evaluable due to disease recurrence or death
◦ Primary endpoint compared between the two groups using a two-sample t-test or non-parametric Mann–
Whitney test
◦ Analysis of covariance (ANCOVA)- to investigate other patient & clinical factors a/w change in MDADI
composite score from baseline to 12 months post- treatment
◦ Chi-squared or Fisher’s exact test- to compare patients in both groups with deterioration of 10 points or more
in the MDADI composite score
30. This is the first randomized study to demonstrate
functional benefit of swallow-sparing IMRT in OPC
Published online before print May 25, 2020
41. ◦ Dmean to inferior PCM : S-IMRT 49.8Gy (IQR 47.1-52.4) vs. Do-IMRT 28.4Gy
(21.3–37.4), p < 0.0001;
◦ Superior & middle PCM dose was S-IMRT 57.2Gy (56.3–58.3) vs. Do-IMRT 49.7Gy
(49.4–49.9), p < 0.0001.
◦ Do-IMRT had significantly higher MDADI scores: S-IMRT 70.3 (SD 17.3) vs. Do-IMRT
77.7 (16.1), p = 0.016.
◦ 3 local recurrences (1 S-IMRT, 2 Do-IMRT) have been reported
◦ No recurrences in spared PCM in DO-IMRT cases
◦ Conclusions:Do-IMRT reduced RT dose to the DARS and improved patient
reported swallowing function compared with S-IMRT.
42. SUMMARY
◦ DARS-Radiation dose delivery to these structures shown to predict swallowing
outcome
◦ SWOAR- SWOARs include the pharyngeal constrictor muscles, the larynx and the
upper oesophageal sphincter
◦ TARGET COVERAGE- is the primary concern, so not to be compromised.
Sparing of normal structures should not be at the cost of target coverage.
Notas del editor
Measure of the number of times an average paper in this journal is cited reflects the yearly average number of citations of articles published in the last two years in a given journal,
Sensory impulses reach the brain stem through cranial nerves VII, IX,and X, while motor control is exercised through cranial nerves IX, X, and XII. The cricopharyngeal sphincter (CPS) relaxes as the bolus reaches the posterior pharyngeal wall before it reaches the CPS.Cranial nerve V contains both sensory and motor fibers a find is important to chewing.
Optimizes the radiation delivery to irregularly-shaped volumes
Simultaneously deliver different radiation doses to the different CTVs
Coronal view of representative swallowing structure contours. Red, superior pharyngeal constrictor; light blue, middle pharyngeal constrictor; yellow, inferior pharyngeal constrictor; dark blue, cricopharyngeus; dark green, esophageal inlet; purple, cervical esophagus; orange, base of tongue; pink, supraglottic larynx; and light green, glottic larynx delineated in accord with methods described by Christianen et al.
Pioneering work by Eisbruch et al. [21] firmly established the strong influence of pharyngeal constrictor muscles (PCM) and glottis-supraglottic larynx (GSL) irradiation on persistent functional impairment after CRT in HNC [21]. Their study additionally showed that 50 Gy was the lowest maximal dose delivered to a stricture volume e a surrogate for late dysphagia, implying that it may be clinically advantageous to minimise the volumes receiving of 50 Gy (V50) in such critical DARS.
