ESTRO 36 Abstract Book

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S338 ESTRO 36 2017
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Material and Methods
Medical records of 516 women diagnosed with luminal B or
HER2-enriched breast cancer that underwent surgical
resection and PORT at Seoul National University Bundang
Hospital (SNUBH) from 2003 to 2012 were retrospectively
reviewed. Based on available IHC and FISH results,
molecular subtypes were defined according to the 2013 St.
Gallen International Expert Consensus recommendation as
LBHER2- in 258 patients (50.5%), LBHER2+ in 136 patients
(26.4%), and HER2-enriched in 122 patients (23.6%).
Results
Significant differences were observed between the
luminal B subgroups, with LB HER2- demonstrating higher
proportions of patients with age younger than 50 years
(p=0.012), high histologic grade (p < 0.001), and positive
expression of p53 (p=0.007). Patterns of care were also
significantly different, with higher rates of systemic
therapy omission in LBHER2- patients (p=0.001). After a
median follow-up duration of 6.3 years, 10-year OS rates
were 87.9% and 97.0% for LB HER2- and LBHER2+, respectively
(p=0.062). On multivariable Cox regression analysis, N
stage in LBHER2- and N stage and histologic grade in LBHER2+
were identified as independent prognostic factors for
relapse within 5 years. When compared with HER2-
enriched breast cancer, LBHER2+ expressed lower rates of
local recurrence (p=0.046) and brain metastasis (p=0.026).
Conclusion
Luminal B breast cancer manifest various patterns of
failure among which trends to poorer prognosis is seen in
the LBHER2- subgroup. The majority of LBHER2+ patients
undergo some form of systemic treatment and
demonstrate relatively better clinical outcomes than
LBHER2- patients. Further stratification of risk prediction,
particularly in the LBHER2- subgroup, and more aggressive
systemic treatment are needed to improve treatment
outcomes, of which p53 may be a potential marker.
PO-0655 Patterns of locorégional failure in women with
breast cancer treated by Postmastectomy Radiotherapy
G. Loganadane1, Z. Xi1, N. Grellier Adedjouma1, H.P. Xu1,
s. Krhili1, A. Chilles1, F. Campana 1, A. Fourquet1, Y.Kirova1
1 Institut Curie, Radiation oncology, Paris, France
Purpose or Objective
At Institut Curie, PMERT(Postmastectomy Electron Beam
Radiation Therapy) is the technique of choice to treat the
chest wall for more than 30 years in women with breast
cancer because it provides equivalent efficacy but
decreases doses delivered to the organs at risk.
Material and Methods
From 964 patients with non-metastatic breast cancer
treated with this technique between 2007 and 2011 at
Institut Curie, data was available for 796 patients. With
median follow-up of 64.1 months, locoregional relapse
free survival at 5 years, metastases free survival at 5 years
and overall survival at 5 years was 90% (IC95%: 88.1-92.4),
83,3% (IC 95% = [80,6 ; 86]) and 90.9% (IC95%: 88.9-93)
respectively. Twenty three patients (2.9%) presented
locoregional recurrences.
The purpose of this study was to analyze the tumor
characteristics and the radiation volumes/doses that
could have resulted in failures. Mapping patterns of
regional recurrences was also performed.
Results
The 23 patients that presented locoregional recurrence
had mostly aggressive biologic features: grade III
(modified Bloom–Richardson–Elston grading) in 17 patients
(74%), high mitotic index in 16 patients (70%) and triple
negative status in 12 patients (52%). Vascular embolism
was present in 11 cases (48%). There were 4 cT1, 11cT2,
1cT3 and 6cT4. The overall positive nodes found in the
lymphadenectomy were p33N+/111N and yp80N+/151N in
patients without and with neoadjuvant chemotherapy.
The median age at recurrence was 59. The median
locoregional relapse free survival and median overall
survival was 28.3 months and 42.8 months respectively.
Local recurrence (chest wall) occurred in 12 cases (56%)
and infield regional recurrence was observed in 3 cases
although sufficient dose was delivered. Marginal or
outfield nodal recurrences were seen in 12 cases (56%) and
involved level I or II in 9 cases. Interestingly, 3 axillary
nodal recurrences occurred outside the ESTRO defined
clinical target volumes. Synchronous and metachronous
distant metastases were found in 14 and 4 patients
respectively.
Conclusion
In our series, the local recurrence resulted mostly from of
biologic radioresistance whereas regional recurrences
were caused by geographical miss. Further follow-up and
careful registration of the recurrencies is needed to
improve the results
PO-0656 Reirradiation+hyperthermia after surgery for
recurrent breast cancer: 70% 5-year local control
S. Oldenborg 1, J. Crezee1, Y. Kusumanto1, R. Van Os1, S.
Oei2, J. Venselaar2, P. Zum Vörde Sive Vörding1, C.
Rasch1, T. Van Tienhoven1
1Academic Medical Center, Radiation Oncology
Hyperthermia, Amsterdam, The Netherlands
2Institute Verbeeten, Radiation Oncology, Tilburg, The
Netherlands
Purpose or Objective
Combining reirradiation (reRT) with hyperthermia (HT)
has shown to be of high therapeutic value for patients with
inoperable locoregional recurrent breast cancer. The
purpose of this study was to analyse the therapeutic effect
and toxicity of reRT+HT following surgery of locoregional
recurrent breast cancer in previously irradiated area.
Material and Methods
Two hundred and twenty-five patients were treated with
re-RT+HT from 1982 till 2006. All patients received
previous high dose radiation (median dose 50Gy with or
without boost), overlapping with the current reRT field.
Forty-two percent of the patients were treated for
previous episodes of locoregional recurrent disease using
either surgery, radiation, systemic therapy, or a
combination of treatment modalities.
At start of reRT+HT there was no macroscopically
detectable recurrence after salvage mastectomy, chest
wall resection, or local excision in 48%, 6%, and 46% of
patients, respectively. ReRT consisted typically of 8x4Gy,
twice a week or 12x3Gy, four times a week. Superficial
hyperthermia was applied once or twice a week using
434MHz Contact Flexible Microstrip Applicators (CMFA),
heating the tumor area to 41-43˚C for one hour.
Results
The treatment was well tolerated; only 3 patients did not
complete treatment as planned due to herpes zoster
infection, toxicity and refusal. Median follow-up time was
56 months. The 5-year infield local control (figure 1) and
overall survival rates were 70% and 60%, respectively. A
longer time interval to current recurrence, concurrent
endocrine treatment, breast recurrences compared to
chest wall recurrences and smaller recurrence sizes before
treatment had a significantly positive effect on the
duration of local control in multivariable analyses. Acute
≥ grade 3 toxicity occurred in 10% of patients. The risk of
late ≥ grade 3 toxicity was 28% after 5 years and consisted
mostly of ulceration (33%). In multivariable analyses the
risk of overall late ≥ grade 3 toxicity was 4.6 times higher
for patients treated with 4Gy fractions and abutted
photon-electron fields (P = 0.032).
Figure 1. Local control including confidence interval