ESTRO 36 Abstract Book

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S337 ESTRO 36 2017
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Tokyo, Japan
3 Sonoda-kai Radiation Oncology Clinic, Radiation
Oncology, Tokyo, Japan
4 St. Luke’s International Hospital, Breast Surgery, Tokyo,
Japan
5 Breast Surgery Clinic, Plastic Surgery, Tokyo, Japan
Purpose or Objective
The use of post-mastectomy radiotherapy (PMRT)
following immediate breast reconstruction has increased
recently. However, its safety has not been well
established. We aimed to evaluate the complication rates
of PMRT to immediate tissue expander/permanent
implant (TE/PI)-based reconstructions for breast cancer
and its association with radiotherapy timing.
Material and Methods
From Jan 2003 to Dec 2014, breast cancer patients who
underwent mastectomy, immediate TE/PI reconstruction
and PMRT were retrospectively reviewed. The
reconstructed breast and supraclavicular region were
treated to a total dose of 50Gy in 25 fractions in most
cases. Patients were divided into two radiotherapy timing
groups, according to whether they received PMRT to a TE
or a PI, to assess the effect of radiotherapy timing on
complications. The rates of complications including
reconstruction failure (RF), re-operation (unplanned
removal or exchange of the TE/PI) and infection were
estimated by Kaplan-Meier analysis. The risk factors
including radiotherapy timing were analyzed by log-rank
test and multivariate Cox proportional hazard model.
Results
A total of 81 patients were included. Of these, 32 patients
(40%) received PMRT to the TE, and 49 patients (60%)
received PMRT to the PI. Median age of patients was 44
years (range, 29-64). Median follow-up was 32 months
(range, 2-120). Total RF, re-operation, and infection rates
were 12.3% (10/81), 13.6% (11/81), and 11.1% (9/81), and
5-year cumulative RF, re-operation, and infection rates
were 16.7%, 16.6%, and 12.2%, respectively. The median
duration between PMRT and RF, re-operation and
infection were 452 days (range, 14–1120), 474 days (range,
14–825) and 223 days (range, 9–654), respectively. No
significant differences were observed in rates of RF, re-
operation and infection with respect to radiotherapy
timing ( P = 0.54, 0.73, 0.31, respectively). In univariate
analysis, age ≥ 55 years was a significant factor for re-
operation (P = 0.009) and infection (P = 0.046). In
multivariate analysis, age 55 years and older was
statistically significant for re-operation (P = 0.02, HR (95%
CI): 4.64 (1.27–16.9)) and infection (P = 0.04, HR (95% CI):
4.6 (1.08–19.5)).
Conclusion
The overall RF rate was 12.3%. There were no significant
differences in rates of RF, re-operation, or infection with
regard to radiotherapy timing. PMRT to reconstructed
breasts of older patients aged 55 years or over can be
expected to result in more complications than in younger
patients.
PO-0653 A heart atlas for breast RT and the influence
of delineation education on observer variability
M. Kirli1 , D. Akçay1, M.M. Barış2, I. Bilkay Görken1
1 Dokuz Eylul Univ. Health Sciences Institute, RADIATION
ONCOLOGY, IZMIR, Turkey
2 Dokuz Eylul Univ. Health Sciences Institute, RADIOLOGY,
IZMIR, Turkey
Purpose or Objective
We developed a heart atlas for cardiac structure
delineation for breast RT and intended to evaluate the
influence of counturing education on contour accuracy
and reduction of intra-inter observer variability and
cardiac dose reporting.
Material and Methods
The data from 16 early left breast cancer patients who
received RT with deep breath hold technique in our clinic
was analyzed. Heart and cardiac substructures (left (LCA)
and right (RCA) coronery arteries, LAD, bilateral atrium
and ventricles) were delineated by eight radiation
oncologists. Then a cardiac atlas was developed on CT by
a cardiac radiologist and experienced radiation oncologist.
The whole heart and subunits were delineated for each
patient and considered as a gold standard (GS) for this
trial. The delineation was repeated on the same patients
by observers after the atlas education. Standard
tangential fields for RT were created on GS volumes for
each patient and dose calculations were repeated for
pre/post-atlas contours. The similarity was assessed by
using Dice (DSC) and Jaccard (JSC) similarity coefficient
indexes. The absolute difference rate was calculated for
dose reporting analysis. The pre/post atlas data analyzed
using Wilcoxon Signed-Rank test.
Results
The inter-observer similarity was increased statisticaly
significant (SS) after education except just for RCA
(p<0,05). Also the similarity comparing observers with GS
increased in heart and all subunits with education. The
increase for both similarity index in left atrium, bilateral
ventricles, LCA+LAD has been found SS (p<0,05). There
wasn’t a significant increase in heart contour similarity
after training. We already obtained 94% of heart contour
consistency, both pre-post atlas delineation which is
higher than other studies in the literature. The intra-
observer similarity showed a heterogeneous distribution
but most of the observers made a delineation much more
similar to GS. The absolute difference rate in dose
reporting after using cardiac atlas was SS for bilateral
atrium, right ventricle, LAD, LCA+LAD, RCA’s maximum
(max) doses and bilateral atrium, right ventricle, and
RCA’s mean doses (p<0,05). Although there was a SS
increase for heart and left ventricle similarity rates by
using cardiac atlas, it didn’t affect the dose reporting
consistency. The max dose reporting differences from the
GS decreased from 16,97% to 9.31% for LAD (p=0,011);
from 14,78% to 9.31% for LCA+LAD (p=0,010). The mean
dose reporting differences from the GS decreased from
34,97% to 22,25% for LAD (p=0.07); from 32,36% to 24,47%
for LCA+LAD (p=0,056). The atlas usage was found to
contribute to a more consisting dose reporting also for max
and mean doses of atriums and right ventricle despite
being on the edge and/or outside of the RT fields (p<0,05).
Conclusion
Cardiac atlas education and using for delineation on heart
and subunits reduce the intra-inter observer variability
and improves dose reporting consistency for left breast
RT.
PO-0654 Failure Patterns of Luminal B Breast Cancer
Following Postoperative Adjuvant Radiation Therapy
N. Choi1, S.W. Lee1, Y. Lim1, K.Y. Eom1,2, E.Y. Kang2, E.K.
Kim2, Y.J. Kim2, J.H. Kim2, S.Y. Park 2, I.A. Kim 1,2
1Seoul National University Hospital Bundang Hospital,
Radiation Oncology, Seoul, Korea Republic of
2Seoul National University Hospital Bundang Hospital,
Breast Care Center, Seoul, Korea Republic of
Purpose or Objective
The establishment of surrogate definitions for breast
cancer molecular subtypes according to IHC has clinically
demonstrated prognostic relevance for improved
objective risk profiling and individualization of treatment
regimens. Defining and stratifying luminal B subtypes,
however, still remains indefinite and is in need of more
distinct differentiation due to its heterogeneous clinical
and molecular characteristics. This study aims to identify
prognostic factors for early relapse in luminal B HER2-
negative (LB HER2-) and -positive (LBHER2+) subgroups, and to
evaluate failure patterns between the latter and HER2-
enriched breast cancer after adjuvant PORT.