604 / 1082
S588
ESTRO 36 2017
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(Rs>0.75) were not included in the multivariate analysis.
A two-variable model was suggested as the optimal order
by bootstrap method. The optimal model (Rs=0.452,
p<0.001) includes V45 of the cervical esophagus
(OR=1.016) and Dmean of the cricopharyngeal muscle
(OR=1.057). The model AUC (Fig1a) was 0.82 (95% CI 0.69-
0.95). The comparison of the predicted incidence of acute
radiation-related toxcity and the actuarial incidence in
the
population
is
shown
in
Figure
1b.
Conclusion
We propose a 2-variable predictive NTCP model including
both cervical esophagus and cricopharyngeal muscle
dosimetric parameters with a good prediction
performance for acute radiation-related toxicity in H&N
cancer pts
EP-1078 Transient xerostomia in head and neck
cancers with significant parotid inclusion in target
volume
A. Datta
1
, A. Mukherji
1
, E. Thiraviyam
1
1
Jawaharlal institute of post graduate medical education
and research, radiation oncology, Puducherry, India
Purpose or Objective
To assess xerostomia patterns in patients requiring
significant parotid inclusion in target volumes for
treatment of locally advanced head and neck cancers.
Material and Methods
30 patients (male = 20, female = 10) with head and neck
cancers (oral cavity = 6, oropharynx = 8, nasopharynx = 3,
larynx = 7) of AJCC stage II = 4, III = 12, and IV = 14 who
were treated with radical chemo radiation from August
2013 – September 2015 and received significant parotid
dose (more than 22 Gy Dmean) were analyzed
retrospectively at 3, 6 and 12 months post completion of
treatment. They received an external radiotherapy dose
of 69.34 Gy EQD2 (to HR-CTV, mean HI – 0.13, mean CI –
0.99) using SIB-IMRT by VMAT technique. Their xerostomia
patterns were recorded based on subjective complaints
(Grade 1 = slight dryness, Grade 2 = moderate dryness,
Grade 3 = complete dryness, Grade 4 = fibrosis).
Results
1 patient died during treatment due to aspiration and 1
patient developed a second primary in lung at 10 months.
The mean of Dmean to right parotid was 43.95 Gy (23-
51.2) to a mean volume of 16.71 cc (9-30.2) while for the
left parotid it was 43.6 Gy (23.1-58.2) to a mean volume
of 16.9 cc (7.7-26.3). The mean spared right parotid
(outside PTV) Dmean was 23.1 Gy (30.2-69.2% of whole
parotid volume, mean volume 42.5%) while for the left
parotid it was 26.3 Gy (22-65% of whole parotid volume,
mean volume 48.7%). At 3 months of completion of
treatment Grade 2 and 3 xerostomia were seen in 2 (6.9%)
and 27 (93.1%) patients respectively. At 6 months Grade 2
and 3 xerostomia were seen in 12 (41.3%) and 17 (58.7%)
patients respectively. While at 12 months Grade 1, 2 and
3 xerostomia were seen in 7 (24.1%), 16 (55.2%) and 6
(20.7%) respectively. 1 patient had a stable residual
disease.
Conclusion
Significant parotid inclusion in target volumes for locally
advanced cases had a reversible loss of parotid function at
12 months of completion of treatment. However, loss of
function was irreversible when the Dmean was greater
than or equal to 50 Gy.
EP-1079 Carotid blowout syndrome after reirradiation
with particle therapy in the head and neck region
J.E. Dale
1
, S. Molinelli
2
, E. Ciurlia
2
, O. Dahl
1,3
, P.
Fossati
2,4
1
Haukeland University Hospital, Department of oncology,
Bergen, Norway
2
CNAO Foundation, Pavia, Italy
3
University of Bergen, Department of clinical science,
Bergen, Norway
4
European Institute of Oncology IEO, Milano, Italy
Purpose or Objective
Carotid blowout syndrome (CBS) is a serious complication
to treatment of neoplasms in the head and neck (H&N)
region. Surgery, infection, necrosis and tumor properties
are the most significant risk factors, but the rate of CBS is
also affected by properties of radiotherapy (RT). Rates
seem to increase in hypofractionated or accelerated
hyperfractionated regimens. We here investigate the
cumulative doses received by the carotid artery (CA) and
CBS-rate in a cohort of patients reirradiated with particle
therapy in the H&N region.
Material and Methods