609 / 1096
S593
ESTRO 36
_______________________________________________________________________________________________
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
Dosimetric information, medical records and tumor
characteristics of 49 patients were collected. CT,
structure set and dose files were available for 32 patients,
making it possible to perform deformable image and dose
registration to allow plan summation and extract precise
cumulative dose statistics for the CA. For the remaining
17 patients a reliable approximation of the cumulative
dose to the CAs was made by comparing printed CT-slices
with isodose curves from the previous RT courses with the
dose distribution from the reirradiation. Corresponding
EQD2 was calculated with an α/β-ratio=3.
Results
Forty-four patients had received 1 prior RT course, while
5 had received 2 prior RT courses. Ten patients received
reirradiation with proton RT and 39 with carbon ion RT
(CIRT). In the 49 patients a total of 74 CAs had been
reirradiated to a median cumulative Dmax
EQD2
of 106 Gy
(RBE) (range: 25-167 Gy (RBE)). Details are presented in
TABLE 1
and
FIGURE 1
. Median time between 1
st
and final
RT was 29 months (range: 3-205 months). Median time of
follow-up was 10 months (range: 1-41 months). Two
patients (4%) experienced profuse oronasal bleeding at 6
and 8 months after reirradiation, both fatal. Cumulative
Dmax
EQD2
for these patients CAs were 130 and 107 Gy
(RBE), respectively. Both had recurrent tumors completely
surrounding the CA. The first patient had undergone
surgery close to the CA prior to the reirradiation. At the
time of bleeding he performed a CT-angiogra phy
revealing a pseudoaneurysm on the CA, making the
diagnosis of CBS highly probable. The second patient had
a recurrent tumor at the site of bleeding. Autopsy was
refused, making it impossible to ascertain if the bleeding
was due to CBS or from pathological tumor vessels. If we
attribute both cases to CBS, the CBS-rate for reirradiated
CAs was 2.7% (95% CI 1.0-6.4%).