ESTRO 36 Abstract Book

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S162 ESTRO 36 2017
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produced equivalent or milder late normal tissue side
effects. This simple radiotherapy technique is
implementable in radiotherapy centres worldwide.
Funding: Cancer Research UK (CRUK/06/003).
SP-0315 Partial breast radiotherapy after breast
conservation for breast cancer: early results from the
randomised DBCG PBI trial
B. Offersen1, H.M. Nielsen1, M.S. Thomsen 2, E.H.
Jacobsen 3, M.H. Nielsen4, L. Stenbygaard 5, A.N.
Pedersen 6, M. Krause7, M.B. Jensen8, J. Overgaard9
1 Aarhus University Hospital, Dept Oncology, Aarhus C,
Denmark
2 Aarhus University Hospital, Dept Physics, Aarhus C,
Denmark
3 Lillebaelt Hospital, Dept Oncology, Vejle, Denmark
4 Odense University Hospital, Dept Oncology, Odense,
Denmark
5 Aalborg University Hospital, Dept Oncology, Aalborg,
Denmark
6 Copenhagen University Hospital- Rigshospitalet, Dept
Oncology, Copenhagen, Denmark
7 University Clinic Carl Gustav Carus- Technical University
Dresden, Clinic for Radiotherapy and Oncology, Dresden,
Germany
8 Copenhagen University Hospital- Rigshospitalet, DBCG,
Copenhagen, Denmark
9 Aarhus University Hospital, Dept Expt. Clin. Oncology,
Aarhus C, Denmark
Objective The risk of local recurrence after adjuvant
radiation therapy (RT) of early breast cancer (BC) is now
so low that ESTRO and ASTRO have suggested guidelines
to select patients who may be safely treated with partial
breast (PBI) and not whole breast irradiation (WBI). In the
Danish Breast Cancer Group (DBCG) the randomized DBCG
PBI trial was initiated to safely introduce PBI as standard
in DK.
Material/Methods Patients ≥60 years operated with breast
conservation for early non-lobular breast cancer (BC) pT1
pN0, ER+, grade 1 or 2, HER2-, margin ≥2mm were enrolled
and randomized to PBI vs WBI, all cases based on 40Gy/15
fr. Strata were institution and endocrine therapy. The
primary endpoint was breast induration 3 years after RT,
secondary endpoints were other morbidities, genetic risk
profile for RT-induced fibrosis and recurrences.
ClinicalTrial NCT00892814.
Results In 6 RT departments in DK and D 882 pts were
enrolled in 2009-16. At analysis 353 pts (40%) had ≥ 3 years
follow up. At 3 years grade 2-3 induration was detected in
6.4% in the PBI arm and in 7.7% in the WBI arm (HR 0.76,
95% CI, 0.39-1.47). At 3 years, comparing the PBI with the
WBI arm there were no differences in dyspigmentation
(8.1% vs 11.0%), telangiectasia grade 2-3 (5.3% vs 8.9%),
edema grade 2-3 (0.6% vs 0.6%), scar grade 2-3 (21.5% vs
17.1%), and global cosmetic outcome (excellent/good)
was 84.3% vs 83.9%, respectively. At 3 years patients
treated with PBI or WBI reported excellent/good
satisfaction with the treated breast in 92.5% vs 91.2% of
cases, and 83.2% vs 81.8% when reporting satisfaction with
the treated breast compared with the non-treated breast.
In the PBI / WBI arm local recurrence was reported in 1
pt/ 2 pts, regional recurrences 0 pt / 0 pt, distant failure
1 pt / 2 pts, new contralateral BC / DCIS 2 pts / 2 pts and
other malignancy 8 pts / 16 pts. One patient had died from
BC, 7 from other malignancy, 7 from non-cancer causes.
Updated results will be provided at ESTRO 36.
Conclusion Using 40/15 fr for PBI in selected early node-
negative BC patients results in few late RT induced
morbidities with no difference compared with WBI. These
results are in harmony with results from the large UK
IMPORT LOW trial using the same RT technique. Thus 40
Gy/15 fr external beam PBI is now DBCG standard for
breast RT in patients fulfilling the inclusion criteria for the
DBCG PBI trial.
Acknowledgement: BVO was supported by The Danish
Cancer Society and CIRRO
OC-0316 Single dose external beam preoperative
radiotherapy in breast cancer: experience and
guidelines
K.R. Charaghvandi1, S. Yoo2, B. Van Asselen1, M.D. Den
Hartogh1, H.J.G.D. Van den Bongard1, J.K. Horton2
1University Medical Center Utrrecht, Radiation Oncology
Department, Utrecht, The Netherlands
2Duke Cancer Center, Department of Radiation Oncology,
Durham, USA
Purpose or Objective
In patients treated with breast-conserving surgery,
suboptimal cosmetic results have been reported following
post-operative 3D-conformal accelerated partial breast
irradiation (APBI) [1]. The delivery of radiation (RT)
preoperatively to the intact tumor enables better target
visualization and reduction in treatment volumes, and
thus, the potential for less normal tissue toxicity [2]. We
compiled our clinical experience and dosimetric data to
develop practical guidelines for this new treatment
approach.
Material and Methods
Dosimetry and toxicity data were pooled from 2
preoperative single dose APBI cohorts and 1 planning-study
[table 1]. In an American dose escalation trial, patients
≥55 years, with non-lobular cT1N0Mx or DCIS received a
single dose of 15, 18 or 21Gy (1.5cm CTV margin) using
IMRT in the prone position (n=32) followed by lumpectomy
within 10 days [fig 1A]. In the Netherlands, the feasibility
of VMAT-based supine APBI (20 Gy to tumor, 15Gy to 20mm
clinical target volume(CTV)) was evaluated initially in a
planning study (n=20) and is currently ongoing in women
≥50 years with cT1-2(max. 3 cm)N0Mx non-lobular
carcinoma (n=10) [fig. 1]. In this trial, lumpectomy is
planned 6 months after RT. Acute toxicity was scored
according to CTCAE version 4.03. Single dose APBI
constraints were derived from pooled OAR estimates. The
limit for optimal OAR dosimetry was set at the 75th
percentile, whereas the 90th percentile represented non-
optimal but acceptable dosimetry. Replanning of the US
cohort was performed to check the adherence of these
constraints for uniform single dose 21Gy APBI with a 20mm
CTV margin (n=32).
Results
In the dose escalation cohort (n=32), grade 1 local
radiation dermatitis, fibrosis and fatigue developed in
39%, 23% and 6% of the cases within 90 days after RT. At a
median follow-up of 57 days in the 15/20Gy simultaneous
boost cohort (n=10) grade 1 fatigue and local fibrosis was
encountered in 90% and 80% of patients, without any
radiation dermatitis. In both cohorts no acute ≥grade 3
toxicity developed. Based on pooled OAR estimates,
optimal dosimetry was defined as a maximum value of
0.7Gy for the mean heart dose, 1.5Gy Dmax for
contralateral breast, 1.3Gy for mean ipsilateral lung dose,
and 12.3Gy as D20cc dose to chest wall [table 1]. All
replanning plans adhered to these constraints. At least
acceptable mean ipsilateral breast dose (max. 5.5Gy) was
achieved in 97% of cases. Optimal skin dosimetry was set
at Dmax ≤100% prescription dose, D1cc ≤13.2Gy and D10cc
≤10.0Gy.