ESTRO 36 Abstract Book

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S163 ESTRO 36
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5 Beatson West of Scotland Cancer Centre, Oncology
Department, Glasgow, United Kingdom
6 Royal Stoke Hospital, Oncology Department, Stoke-on-
Trent, United Kingdom
7 Aukland Hospital, Physics Department, Aukland, New
Zealand
8 Nuffield Health Cheltenham Hospital, Department of
Surgery, Cheltenham, United Kingdom
9 Norfolk and Norwich University Hopsitals NHS
Foundation Trust, Oncology Department, Norwich,
United Kingdom
11 Kings College London, Oncology Department, London,
United Kingdom
12 Clatterbridge Cancer Centre, Oncology Department,
Bebington, United Kingdom
13 Mount Vernon Cancer Centre, Radiotherapy
Department, Northwood, United Kingdom
14 Royal Cornwall Hospital, Oncology Department, Truro,
United Kingdom
15 Independent Cancer Patient Voice, London, United
Kingdom
16 Institute of Cancer Research, Academic Department of
Radiotherapy, London, United Kingdom
Background: Local cancer relapse rates after breast
conservation surgery followed by radiotherapy have fallen
sharply in many countries with risk influenced by patient
age and clinico-pathological factors. In women at lower
than average risk of local relapse, partial breast
radiotherapy restricted to the vicinity of the original
tumour is hypothesised to improve the balance of
beneficial versus adverse effects compared with whole
breast radiotherapy.
Methods: The IMPORT LOW trial (ISRCTN12852634)
recruited women aged ≥50 years after breast conserving
surgery for invasive ductal adenocarcinoma pT≤3cm, pN0-
3, G1-3 and ≥2mm resection margins. Using 15 daily
treatments, patients were randomly allocated (1:1:1) to
40 Gy whole breast radiotherapy (control), 36 Gy whole
breast plus 40 Gy to partial breast (reduced dose) or 40 Gy
partial breast only (partial breast). Primary endpoint was
ipsilateral local relapse rate (80% power to exclude a
+2.5% non-inferiority margin at 5 years for each test
group).
Findings: Between May 2007 and October 2010, 2018
women were recruited (control n=675, reduced dose:
n=674, partial breast: n=669). With a 72.2 month median
follow-up (IQR 61.7-83.2), 5-year local relapse rates were
1.1% (95%CI 0.5-2.3), 0.2% (0.02-1.2) and 0.5% (0.2-1.4) in
control, reduced dose and partial breast groups. Absolute
differences in local relapse rate compared with the
control group were -0.73% (-0.99, 0.22) for the reduced
dose and -0.38% (-0.84, 0.90) for the partial breast groups,
demonstrating non-inferiority for both test groups.
Photographs, patients and clinicians reported similar or
lower levels of adverse effects after reduced dose or
partial breast radiotherapy compared with whole breast
radiotherapy (see Table 1).
Interpretation: At 5 years, partial breast and reduced dose
radiotherapy showed local relapse rates non-inferior to
that observed following whole breast radiotherapy and
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.
Jacobsen3, M.H. Nielsen4, L. Stenbygaard 5, A.N.
Pedersen6, M. Krause7, M.B. Jensen8, J. Overgaard9
1Aarhus University Hospital, Dept Oncology, Aarhus C,
Denmark
2Aarhus University Hospital, Dept Physics, Aarhus C,
Denmark
3Lillebaelt Hospital, Dept Oncology, Vejle, Denmark
4Odense University Hospital, Dept Oncology, Odense,
Denmark
5Aalborg University Hospital, Dept Oncology, Aalborg,
Denmark
6Copenhagen University Hospital- Rigshospitalet, Dept
Oncology, Copenhagen, Denmark
7University Clinic Carl Gustav Carus- Technical University
Dresden, Clinic for Radiotherapy and Oncology, Dresden,
Germany
8Copenhagen University Hospital- Rigshospitalet, DBCG,
Copenhagen, Denmark
9Aarhus 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.