ESTRO 36 Abstract Book

653 / 1096

S637 ESTRO 36
_______________________________________________________________________________________________
Dmean and V20Gy of electron plan were lower (p=0.080 and
0.043, respectively) than those of tangential plan, while
Dmax between two plans were less different. For target
coverage, all of Dmean, Dmax, D min, conformity index (CI) and
homogeneity index (HI) of electron plan were higher than
those of tangential plan (p=0.043, 0.043, 0.043, 0.225,
0.034, respectively).
Conclusion
Chest wall electron beam therapy with PTB reduced high
dose exposed cardiac and lung volume with clinically
acceptable target coverage compared with tangential
technique. Postmastectomy radiotherapy using PTB might
be effective for left breast cancer patients to reduce risk
of cardiac disease and lung morbidity.
EP-1173 Understanding variations in the use of
hypofractionated radiotherapy for breast cáncer
J.M. Borras1, J. Prades1, M. Algara2, J.A. Espinàs1, B.
Farrús3, M. Arenas4, V. Reyes5, V. Garcia-Reglero6, M.J.
Cambra7, E. Rubio Calatayud8, L. Anglada9, A. Eraso10 , A.
Pedro11, M.J. Fuentes-Raspall 12, V. Tuset13
1 Institut Català d'Oncologia, Cancer plan, L'Hospitalet de
Llobregat, Spain
2 Hospital de l'Esperança- Parc de Salut Mar,
Radiotherapy, Barcelona, Spain
3 Hospital Universitari Clinic de Barcelona, Radiotherapy,
Barcelona, Spain
4 Hospital Universitari Sant Joan de Reus, Radiotherapy,
Reus, Spain
5 Hospital Universitari Vall d´Hebron, Radiotherapy,
Barcelona, Spain
6 Hospital Universitari Arnau de Vilanova, Radiotherpy,
Lleida, Spain
7 Hospital General de Catalunya- Institut Oncològic del
Vallès, Radiotherpay, Barcelona, Spain
8 Consorci Sanitari de Terrassa, Radiotherapy, Terrassa,
Spain
9 Institut Català d'Oncologia- Girona, Radiotherapy,
Girona, Spain
10 Institut Català d'Oncologia, Radiotherapy, L'Hospitalet
de Llobregat, Spain
11 Hospital Clínica Plató, Radiotherapy, Barcelona, Spain
12 Hospital de la Santa Creu i Sant Pau, Radiotherapy,
Barcelona, Spain
13 Hospital Universitari Germans Trias i Pujol,
Radiotheraoy, Badalona, Spain
Purpose or Objective
Radiation oncology guidelines favour hypofractionated
whole-breast radiotherapy (HWBRT) over more
conventional schemes in the conservative treatment of
breast cancer, but its adoption still varies in clinical
practice. This study assessed the patterns of HWBRT use
and adoption in Catalonia (Spain).
Material and Methods
We used a mixed-methods approach based on an
explanatory sequential design, first collecting and
analysing quantitative data on HWBRT use (> 2.5 Gy per
fraction) in 11 public radiotherapy centres (2005–2015)
and then performing 25 semi-structured interviews with
all department heads and reference radiation
oncologist/s.
Results
Of the 34,859 patients fulfilling the study criteria over the
study period, just 12% were hypofractionated, reaching a
rate of 29% in 2015 (p<0.001). Our analysis showed a
narrowing age gap between patients receiving
conventional fractionation and hypofractionation in
centres leading adoption. However, there were important
differences in clinicians’ interpretation of evidence and
selection of patients for specific indications, both within
and between departments. Clinical management of
radiotherapy departments played a major role.
Conclusion
In tackling inequitable access to HWBRT, a rational,
evidence-based approach should ideally converge with
professional perspectives, the factors influencing the
interpretation of the evidence, and the organisational
context, including existing dissemination channels.
EP-1174 impact of radiotherapy to posterior
supraclavicular and posterior triangle area in breast
cancer
S.H. Liu 1, Y.C. Huang 2, Y.J. Chen1
1Mackay Memorial Hospital, Department of Radiation
Oncology, Taipei, Taiwan
2Graduate Institute of Chinese Medical Science, China
Medical University, Taichung, Taiwan
Purpose or Objective
For patients with 4 or more lymph nodes involvement,
regional nodal irradiation (RNI) is associated with
increased locoregional control and overall survival (OS).
The main radiotherapy (RT) volume for RNI includes
axillary, supraclavicular, and/or internal mammary nodes.
However, whether the posterior supraclavicular area and
the posterior triangle of the neck (PSPT) should be
included in RNI remains unclear. The object of this study
was to retrospectively review our clinical experience of
RNI to PSPT or not in N2-3 breast cancer patients as a
reference for target delineation.
Material and Methods
Patients with N2-3 breast cancer who received definitive
surgery and/or neoadjuvant/adjuvant therapy during
2006–2013 were reviewed. The delivery of adjuvant RT and
the coverage for RNI were at the discretion of treating
physicians. To ensure precise delineation and dosimetry,
only patients treated using the technique of intensity-
modulated radiotherapy (IMRT) to regional nodal area
were enrolled. The patterns of recurrence including the
PSPT region were examined. The locoregional control rate
(LCR), distant metastasis-free rate (DMFR), disease-free
survival (DFS), and OS were analyzed using Kaplan-Meier
method, and survival estimates were obtained with log-
rank test and the Cox proportional hazard model.
Results
Of 256 N2-N3 breast cancer patients who were diagnosed
and received operation in a medical center, 184 cases
were eligible for the study. Among these women, 62
received RNI according to the recommended volume by
RTOG consensus (RC group), 57 had additional volumes of
PSPT (RC+PSPT group), and 65 did not have adjuvant RT
(NRT group). Median follow-up was 62.8 months for the
entire cohort. There was higher LCR (p=0.006, 90.8% vs.
78.5% at 5 years) and OS (p=0.007, 82.7% vs. 64.8% at 5
years) for the patients with adjuvant RT (RC and RC+PSPT)
compared to those without RT (NRT). No difference in
DMFR (p=0.508, 69.6% vs. 63.4% at 5 years) and DFS
(p=0.243, 68.2% vs. 69.2% at 5 years) were noted. Among
women with adjuvant RT, there was no statistical
difference between RC and RC+PSPT groups (LCR:
p=0.693, 93.1% vs. 89.9% at 5 years; DMFR: p=0.501, 66.2%
vs. 73.9% at 5 years; DFS: p=0.606, 66.2% vs. 71.6% at 5
years; OS: p=0.548, 83.5% vs. 83.5% at 5 years). In details,
locoregional recurrence was found in 4 (6.5%), 6 (10.5%),
and 17 (26.2%) patients in the RC, RC+PSPT and NRT group,
respectively. Among these patients, no PSPT recurrence
was noted in RC+PSPT group, whereas there were 2 (50%)
in the RC group and 11 (64.5%) in the NRT group.
Conclusion
Adjuvant RNI significantly increased LRC and OS for N2-N3
breast cancer patients. Local recurrence specifically
noted in PSPT might be diminished by additional inclusion
in the regional nodal irradiation volumes. This impact may
not translate to the changes in LCR, DMFS, DFS, and OS in
our experience. Further prospective investigation is