ESTRO 36 Abstract Book

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S624 ESTRO 36 2017
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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. Jeon1, K.H. Shin1, S.Y. Park1, J.M. Park1
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 cm3 and 56.9 cm3 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.
EP-1158 Vmat radiation induced nausea/vomiting in
adjuvant breast cancer radiotherapy: dosimetrical
issues.
G. Lazzari 1, A. Terlizzi1, B. Turi1, M.G. Leo1, D. Becci1, G.
Silvano1
1Azienda Ospedaliera SS. Annunziata Presidio Osped,
Radiology, Taranto, Italy
Purpose or Objective
Breast radiotherapy is associated with a minimal
emetogenic risk in MASCC/ESMO guidelines. Although the
emetogenic potential risk is estimated < 30%, VMAT
adjuvant radiotherapy may induce an unexpected acute
toxicity defined radiation induced nausea and vomiting
(RINV) as we observed in our experience. Aim of our report
is to find a correlation between dosimetrical factors and
RINV occurrence in our patients (pts).
Material and Methods
In our institutionfrom January 2013 to May 2016 106 breast
cancer pts were treated with adjuvant radiotherapy (RT)
in VMAT modality. Al pts had surgery ( conservative or
radical). Mean age was 54 years. Neoadjuvant or adjuvant
chemotherapy was given in 6 pts and 68 pts respectively
(62 pts had high risk emetogenic agents combination, 12
pts had CMF). Left side breasts were treated with in 95
pts, right breast RT occurred in 11 pts. CT planning
included all the chest from C6 to D12-L3 vertebrae. PTV
consisted of residual breast or chest wall and nodal sites.
According ICRU 83 , the prescribed dose was 50 Gy total
dose (2 Gy/25) to breast-chest wall and internal mammary
chain (10 pts). Supraclavicular nodes (36 pts) were treated
simultaneously , 1.92 Gy/25 fractions to 48 Gy total dose.
VMAT was planned on treatment planning system Oncentra
Masterplan® (collapsed cone algorithm) or Monaco®
(Monte Carlo photon algorithm) and consisted of dual arc
plan (170°/340° for left breast; 190°/20° for right breast)
and 6 MV photons beams. In all the pts we retrospectively
contoured on CT planning a volume containing the
anatomical structures of emetic vagal-simpatical
afferental pathways as the celiac plexus and
gastroesophageal junction (GEJCPs). This area was
identified as an organ at risk (OAR) for which the total
volume, Dmax, Dmean and D1cc were calculated.
Univariate analysis with χ2, t-test and Pearson covariance
were used for statistical analysis.
Results
On 106 pts, 68 (64%) patients complained acute RINV
according CTCAE v.3 criteria G1 nausea in 46 pts (43%), G2
nausea in 13 pts (12%), G1 vomiting in 8 pts (7 %) were
recorded. Symptoms occurred at 34 Gy delivered dose
(mean 30 Gy, range 20-34). In right side irradiated breasts
RINV occurred in 3 pts (27%), in left side RT in 65 pts (60%).
RINV was related to a Dmax >10 Gy on GEJCPs (p < 0.005).
G1 vomiting and G2 nausea were related to a Dmax > 17
Gy (p < 0.005) and to a Dmax > 15 Gy (p < 0.005)
respectively. Radiation breast side, age, systemic
therapy, nodal radiation and PTVs volume values were not
statistically significant for RINV.
Conclusion
RINV in breast radiation is not a common acute side effect.
VMAT in breast radiation is responsible for a low dose bath
to nearest structures as the GEJCPs and this may explain
RINV in our cases. A useful constraint as Dmax < 10 Gy on
GEJCPs like a serial structure may be considered in VMAT
breast planning to avoid RINV.
EP-1159 Hypofractionated adjuvant radiotherapy and
concomitant trastuzumab for breast cancer: 5-year
results
M. Pasetti 1, A. Fodor1, C. Sini2, F. Zerbetto1, P. Mangili2,
P. Signorotto2, I. Dell'Oca1, C. Gumina1, M. Azizi1, A.M.
Deli 1, P. Passoni1, N. Slim1, C.L. Deantoni1, B. Noris
Chiorda1, S. Foti1, A. Chiara1, G. Rossi1, C. Fiorino2, A.
Bolognesi1, N.G. Di Muzio1
1San Raffaele Scientific Institute, Department of
Radiotherapy, Milano, Italy
2San Raffaele Scientific Institute, Medical Physics,
Milano, Italy
Purpose or Objective