979 / 1082
S963
ESTRO 36 2017
_______________________________________________________________________________________________
Clinical Oncology, Edinburgh, United Kingdom
2
Western General Hospital- Edinburgh Cancer Centre,
medical Physics, Edinburgh, United Kingdom
Purpose or Objective
To assess if the target coverage and dose to organs at risk
(OARs) from a vaginal vault brachytherapy CT plan are
representative of dose delivered during the actual
treatment.
Material and Methods
28 patients scheduled for post-operative vaginal vault
brachytherapy had an initial planning CT scan (CT1) done
a few days before the first fraction, with the vaginal
cylinder in-situ to generate a treatment plan. The PTV was
the cranial 4cm of the vagina to a depth of 0.5cm, and the
OARs outlined included the rectum, sigmoid, small
bowel and bladder. On the day of the first fraction the
patients has a second CT scan with the vaginal cylinder
(CT2) and the PTV and OARs were outlined. Then the plan
from CT1 was superimposed on CT2 to assess for variation
in V100 and d90 to the PTV and the d2cc to the OARs.
Prescribed dose was 21Gy in 3 fractions to the PTV, aiming
for a V100 of >95% and d90 of 7Gy per fraction.
Results
Total of 56 scans were analysed. Mean PTV V100 for CT1:
95.8% (range 99.6% - 83.2%); CT2: 96% (range 99.8% – 90%).
Mean d90 for CT1: 7.4Gy( range 7.8 – 6.7Gy); CT2: 7.3Gy
(range 7.9 – 6.3Gy). Mean difference in d90 per fraction
was 0.23 Gy per fraction (range: 0.56 – 0.01Gy).
Small
Bowel Sigmoid Rectum Bladder
Mean d2cc (Gy)
CT1
3.16
(range
7.0
-
0.3)
4.1
(range
6.4 - 1.9)
5.5
(rnage
7.0 - 3.9)
6.0
(range
6.7 - 4.9)
Mean d2cc (Gy)
CT2
3.18
(range
6.8
-
0.3)
3.8
(range
5.9 - 1.4)
5.6
(range
7.1 - 3.6)
6.0
(range
7.2 - 4.9)
Man difference
in d2cc between
CT1 and CT2
0.8
0.7
0.9
0.5
Conclusion
The variation in d2cc doses when using the initial CT plan
on the second scan taken on the day of the first fraction
were minimal and not clinically significant. Differences in
PTV coverage are mostly due to slight differences in PTV
outlining mainly because of changes in the angle of the
cylinder compared to the treatment couch. There does not
appear to be the need to plan every single fraction for
post-operative vaginal vault brachytherapy as the
dosimetry using the initial plan was representative of the
dose delivered on the day of treatment.
EP-1777 Cervical cancer outcomes in the high-dose-
rate brachytherapy era: A single institution experience
N. Alyamani
1
, G. Bhattacharya
1
, R. Samant
1
, C. E
1
, T.
Le
1
, K. Lupe
1
1
The Ottawa Hospital Regional Cancer Centre, Radiation
Oncology, Ottawa, Canada¨
Purpose or Objective
Since 2008, the management of cervix cancer with primary
radiotherapy at our institution has included the use of HDR
(high-dose-rate) brachytherapy; prior to this, LDR (low-
dose-rate) brachytherapy was used. The aim of this study
is to review our experience with HDR brachytherapy and
to evaluate patient outcomes.
Material and Methods
A retrospective review of cervical cancer patients treated
with curative intent using radical external beam
radiotherapy and HDR brachytherapy, from 2008 to 2014
inclusive was performed. Overall survival (OS) and
progression-free survival (PFS) were analyzed using the
Kaplan-Meier method.
Results
A total of 76 patients were treated with radical
radiotherapy incorporating HDR brachytherapy during this
time period. The median age was 47 years with a median
follow-up of 38 months. The histology was squamous cell
carcinoma in 88% and adenocarcinoma in 11%. The
distribution according to stage was as follows: stage I 16%,
stage II 38%, stage III 40% and stage IV 5%. All patients
received weekly Cisplatin chemotherapy with a median of
5 cycles delivered. The median dose of external beam
radiotherapy was 45Gy delivered in 25 fractions over 5
weeks. The median brachytherapy dose was a total of
24Gy in 3 weekly fractions of 8Gy. The 5-year OS and PFS
rates were 74% and 63% respectively. The 5-year
locoregional control rate was 82%. There were a total of
25 failure and 12 of these had a component of local
failure. However, only 3 of these had exclusively local
failure. Of note is that the majority of patients with
recurrences had a component of distant failure (19/25;
representing 77% of relapses). Using the Common
Terminology Criteria for Adverse Events version 4.0
(CTCAE v.4.0), it appears as though severe acute (Grade
3/4) Gastrointestinal (GI) and Genitourinary (GU) toxicity
was present in approximately 21% of patients, along with
Grade 3/4 Hematologic toxicity seen in 34%. These results
are similar to the published literature and compare
favorably with our previous LDR brachytherapy
experience.
Conclusion
There has been a shift towards incorporation of HDR
brachytherapy world-wide in the management of cervix
cancer and our institutional experience indicates that
long-term outcomes for patients remain good, with
generally high rates of local control.
EP-1778 Combined intracavitary-interstitial IGABT of
cervical cancer –First dosimetric experience in
Hungary
G. Fröhlich
1
, J. Vízkeleti
1
, N.N. Anhhong
1
, N. Mészáros
1
,
T. Major
1
, C. Polgár
1
1
National Institute of Oncology, Centre of Radiotherapy,
Budapest, Hungary
Purpose or Objective
Dosimetric evaluation of combined intracavitary-
interstitial high-dose-rate image-guided adaptive
brachytherapy (IGABT) of cervical cancer, implemented in
Hungary.
Material and Methods
Since April 2016, 9 patients with cervical cancer were
treated with overall 22 fractions of combined
intracavitary-interstitial IGABT. After transrectal US-
guided implantation of Utrecht or Fletcher applicator and
needles, High-Risk-CTV (HR-CTV), bladder (b), rectum (r)
and sigmoid (s) were contoured on CT, based on the post-
teletherapy MRI of the patients. Dose-volume criterions of
treatment plans were based on the recommendations of
GEC-ESTRO Gyn WG. Treatment plans were compared to
the conventional intracavitary 2D plans (the dose was
prescribed to point A) and to CT-based 3D optimized plans
(without needles) with Friedman and Kruskal-Wallis
ANOVA and Spearman rank correlation tests.
Results
Median number of implanted needles was 3 (range: 2-4),
mean volume of HR-CTV was 39.8 cm
3
(8.3-100.2 cm
3
). For
intracavitary-interstitial IGABT, intracavitary 2D and
intracavitary 3D optimized plans, difference was found
almost in all dose-volume parameters: V100 were 90.4%,
83% and 87.1% (p=0.043), DHI were 0.34, 0.30 and 0.27
(p=0.0137), D2(b) were 4.8 Gy, 6.9 Gy and 5.9 Gy (p<001),
D2(r) were 3.3 Gy, 6.6 Gy and 3.5 Gy (p<0.001), D2(s) were