ESTRO 36 Abstract Book

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S288 ESTRO 36 2017
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A. Vestergaard1, L. Muren1, H. Lindberg2, L. Dysager3, K.
Jakobsen 2, H. Jensen3, J. Petersen1, U. Elstrøm1, A. Als4,
M. Høyer4
1 Aarhus University Hospital, Department of Medical
Physics, Aarhus C, Denmark
2 Copenhagen University Hospital- Herlev, Department of
Oncology, Herlev, Denmark
3 Odense University Hospital, Department of Oncology,
Odense, Denmark
4 Aarhus University Hospital, Department of Oncology,
Aarhus C, Denmark
Purpose or Objective
Large changes in bladder shape and size during a course of
radiotherapy (RT) make adaptive RT (ART) appealing in
the treatment of this tumour site. Patients with bladder
cancer unfit for surgery and chemotherapy were treated
in a multicentre phase II trial of daily plan selection with
the primary aim of reducing gastro-intestinal (GI)
morbidity. Acute and late morbidity is reported from the
trial and the frequency of acute diarrhoea is compared to
a previous cohort of similar patients treated with non-
adaptive RT (non-ART).
Material and Methods
All 54 patients (median age 80 years) received 60 Gy in 30
fractions to the bladder; in 41 of the patients the pelvic
lymph nodes were simultaneously treated to 48 Gy. Cone-
beam CT (CBCT) image guidance was used for daily set-up
and treatment was delivered by volumetric modulated arc
therapy (VMAT). The first five fractions were delivered
using large, population-based margins(non-ART: 20 mm
sup and ant; 15 mm post; 10 mm lat and inf); the bladder
contours from the CBCTs acquired during the first four
daily treatment sessions were used to create a library of
three plans, corresponding to a small, medium and large
size bladder. From fraction six all patients were treated
using daily online plan selection, where the smallest plan
covering the bladder was selected prior to each treatment
delivery. Morbidity scoring was performed at baseline,
every second week during RT and two weeks as well as 3,
12 and 24 month after RT using CTCAE v. 4.0. The
frequency of any grade 2 or higher GI morbidity was
evaluated at treatment completion. Peak acute morbidity
was assessed using the scorings until 3 months after RT
and peak late morbidity was evaluated after 12 months of
follow up. The frequency of peak acute diarrhoea was
compared to the cohort treated with non-ART. Acute and
late genito-urinary (GU) morbidity was also recorded.
Median follow-up was 12 months.
Results
Frequency of use of small size plans was 46%, medium 25%
and large 31%. The median volume ratio of PTV-ART vs.
non-ART across the treatment course was 0.68 (range:
0.46-0.93 for individual patients). Any GI morbidity grade
2 or higher was reported by 11 patients (20%) at treatment
completion and returned to baseline level at the 3 months
follow-up. Peak acute grade 2 or higher diarrhoea was
reported by 12 patients (22%). In the previous cohort of
patients treated with non-ART, 15 (30%) reported grade 2
or higher diarrhoea. An expected increase in acute GU
morbidity during RT was observed compared to baseline
scoring, but primarily grade 1. Late GU morbidity was
comparable to baseline.
Conclusion
Daily adaptive plan selection in RT of bladder cancer
results in a considerable dose sparing of normal tissue.
This phase II trial indicates that adaptive RT can be
delivered with low risk of morbidity.
Poster Viewing : Session 12: Gynaecology and prostate
PV-0548 The role of adjuvant therapy in stage IA
serous and clear cell uterine cancer: a pooled analysis
M.X. Qu1, V. Velker2, E. Leung 3, J. Kwon4, M.A. Elshaikh5,
I. Kong6, N. Logie7, L.C. Mendez3, L. Van der Putten4, E.
Donovan6, A.R. Munkarah8, E.M. Wiebe7, A.V. Louie2, D.P.
D'Souza2
1Queen's University, Oncology, Kingston, Canada
2Western University, Radiation Oncology, London,
Canada
3University of Toronto, Radiation Oncology, Toronto,
Canada
4University of British Columbia, Obstetrics &
Gynaecology, Vancouver, Canada
5Henry Ford Hospital, Radiation Oncology, Detroit, USA
6McMaster University, Oncology, Hamilton, Canada
7University of Alberta, Oncology, Edmonton, Canada
8Henry Ford Hospital, Gynecology/Oncology, Detroit,
USA