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S629
ESTRO 36
_______________________________________________________________________________________________
4
National Cancer Center, Study Coordination Section,
Chuo, Japan
5
National Cancer Center Hospital, Radiation Oncology,
Chuo, Japan
6
Kindai University Faculty of Medicine, Radiation
Oncology, Osakasayama, Japan
7
Osaka Medical Center for Cancer and Cardiovascular
Diseases, Radiation Oncology, Osaka, Japan
8
Saitama Cancer Center, Radiation Oncology, Kitaadachi,
Japan
9
Hiroshima University Graduate School of Biomedical
Science, Radiation Oncology, Hiroshima, Japan
10
Niigata Cancer Center Hospital, Radiation Oncology,
Niigata, Japan
11
National Cancer Center Hospital East, Radiation
Oncology and Particle Therapy, Kashiwa, Japan
12
Shizuoka Cancer Center, Radiation and Proton Therapy
Center, Sunto, Japan
13
Graduate School of Medicine- Chiba University,
Diagnostic Radiology and Radiation Oncology, Chiba,
Japan
14
Hyogo Cancer Center, Radiation Oncology, Akashi,
Japan
15
Shikoku Cancer Center Hospital, Radiotherapy,
Matsuyama, Japan
16
Aichi Cancer Center Hospital, Radiation Oncology,
Nagoya, Japan
17
The University of Tokyo Hospital, Radiology, Bunkyo,
Japan
18
Tochigi Cancer Center, Radiotherapy, Utsunomiya,
Japan
19
Osaka University Graduate School of Medicine,
Radiation Oncology, Suita, Japan
20
Graduate School of Medicine- Kyoto University,
Radiation Oncology and Image-applied Therapy, Kyoto,
Japan
21
Tokyo Metropolitan Cancer and Infectious diseases
Center- Komagome Hospital, Radiology, Bunkyo, Japan
22
Tokyo Women’s Medical University, Radiation
Oncology, Shinjuku, Japan
23
University of Tsukuba, Radiation Oncology, Tsukiba,
Japan
Purpose or Objective
To evaluate the safety and efficacy of short-course
hypofractionated whole-breast irradiation (HWBI) on
Japanese women after breast-conserving surgery (BCS), a
prospective single-arm confirmatory trial (JCOG0906,
UMIN000003200) has been conducted in 25 hospitals.
Material and Methods
Japanese women who had invasive breast cancer with
clinical tumor size of 3 cm or less, no or one to three
pathologically positive lymph nodes and pathologically
negative inked margin were prospectively registered after
BCS with or without adjuvant chemotherapy. The HWBI of
42.56Gy/16fr was delivered to the whole-breast without
regional nodal irradiation, and a boost irradiation (BI) of
10.64Gy/4fr to the original tumor bed was added when the
surgical margin was 5 mm or less. The recommended
treatment period was within 29 days for HWBI and 33 days
for HWBI and BI. The primary endpoint was the proportion
of pre-specified eight items of grade 2 or higher late
adverse reactions (ARs) including telangiectasia,
ulceration, fibrosis-deep connective tissue, fracture,
pneumonitis, cardiac ischemia/infarction, pericardial
effusion and pain-breast occurring between 91 days and
three years from the start of HWBI. The sample size was
set as 310 patients with one-side alpha of 5%, power of
90%, threshold value of 8%, and expected value of 4%,
estimated from the proportion of the late ARs on the
historical control including 703 patients followed up for
three years or more after conventional fractionated
whole-breast irradiation (CWBI) in our pilot survey prior to
the present trial. Secondary endpoints included the
proportion of treatment completion within the
recommended period, early adverse events (AEs)
occurring during 90 days from the start of HWBI, overall
survival (OS), disease-free survival (DFS), ipsilateral-
breast relapse-free survival (IB-RFS), and the proportion
of breast cosmetic change. Early AEs and late ARs were
evaluated using CTCAE ver3.0. Survival time was
estimated by the Kaplan-Meier methods.
Results
Between 2010 and 2012, 312 women were registered. 306
patients received HWBI and 66 patients received HWBI
with BI, but six chose CWBI prior to the start of irradiation.
301 patients (96.5%; 95%CI: 93.8-98.2) were treated within
the recommended period. Evaluation of early AEs found
that 38 patients (12.4%) had grade 2, including 25 patients
(8.2%) with radiation dermatitis, and no patients had
grade 3/4. On 306 patients receiving HWBI, 3-years OS,
DFS and IB-RFS were 99.7% (95%CI: 97.7-100), 95.7%
(95%CI: 92.7-97.5) and 99.0% (95%CI: 97.0-99.7). Among
303 (97%) patients, evaluation of late ARs found that 13
patients (4.3%; 90%CI: 2.6-6.7) had grade 2/3, including
one of grade 3 pneumonitis. None had grade 4 or
treatment-related death.
Conclusion
Short-course HWBI is considered as one of the standard
treatments for Japanese women with margin-negative
invasive breast cancer after BCS. Further follow-up is
continued and cosmetic outcome will be analyzed.
EP-1157 Serial changes of post-lumpectomy seroma
during MRI-guided partial breast irradiation
S.H. Jeon
1
, K.H. Shin
1
, S.Y. Park
1
, J.M. Park
1
1
Seoul National University Hospital, Radiation Oncology,
Seoul, Korea Republic of
Purpose or Objective
After breast conserving surgery, the volume of post-
lumpectomy seroma changes by time. We analyzed serial
changes of seroma volume (SV) using magnetic resonance
image (MRI) to investigate the possible benefit of adaptive
radiation therapy during partial breast irradiation (PBI).
Material and Methods
From October 2015 to July 2016, 37 patients were
prospectively included in the study. A total dose of 38.5
Gy in 3.85 Gy fractions once daily was prescribed to the
planning target volume (PTV). The PTV was defined as
unequal margins of 1-1.5cm added according to the
directional safety margin status of each seroma.
Treatment was done using MRI-guided radiation therapy
(ViewRay system). During the 10 fractions of treatment,
MRI scans were acquired at the time of simulation, 1st,
6th and 10th fractions.
Results
The average time intervals of surgery-simulation,
simulation-1st, 1st-6th, and 6th-10th fractions were 23.1,
8.5, 7.2, and 5.9 days, respectively. SV was smaller during
treatment than at simulation in 34 patients. Mean SV
decreased from 100% at simulation to 65%, 55%, and 47%
at each MRI scan. Age, body mass index, tumor size,
seroma location, SV and delivery of radiotherapy did not
showed association with SV change (p>0.05, student’s t-
test). In 34 patients with decreased SV, mean PTVs were
84.7 cm
3
and 56.9 cm
3
at simulation and 6th fraction,
respectively, and their difference was proportional to SV
at simulation (r=0.832, p<0.001, pearson’s correlation
test).
Conclusion
During PBI, rate of SV change is associated with time
elapsed from surgery. Frequent monitoring of seroma
change with MRI seems helpful for all patients receiving
PBI.