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pN stage. Patients in the BCT and the ME only group
showed a significant higher risk for LRR compared to the
ME+RT group (HR 3.29, p 0.037 and HR 4.45, p 0.020
respectively).
Ten year BCSS was 87 %, 84 % and 75 % for the BCT, ME+RT
and ME only group, respectively. BC-specific mortality
increased with higher pT and pN stages (HR 1.59, p 0.006
and HR 1.82, p < 0.0001, respectively). Patients with an
axillary lymph node dissection (HR 2.81, p 0.016) and with
lymphovascular invasion (HR 1.72, p 0.053) had lower
BCSS. Adjuvant chemotherapy administration was a
protective factor for BC-specific mortality (HR 0.58, p
0.024). Multivariable analysis was conducted to assess
differences between the three groups with correction for
pT, pN, lymphovascular invasion, lymph node dissection
and adjuvant chemotherapy. Patients in the ME only group
had significant lower BCSS compared to the BCT and the
ME+RT group (HR 1.84, p 0.047 and HR 2.88, p 0.003,
respectively). No significant differences were observed for
the comparison of BCT versus ME+RT. BCSS curves for the
three groups as estimated from the multivariable model
are presented in figure 1.
Conclusion
TNBC patients treated with ME without adjuvant RT
showed significant lower BCSS compared to patients
treated with BCT or ME+RT and significant more LRR
compared to ME+RT when corrected for known
clinicopathological prognostic factors.
PO-0651 Five year outcome and soft tissue toxicity of
breast cancer hypofractionated adjuvant radiotherapy
F. Zerbetto
1
, A. Fodor
1
, C. Sini
2
, P. Mangili
2
, M. Pasetti
1
,
P. Signorotto
2
, C. Fiorino
1
, I. Dell'Oca
1
, A. Chiara
1
, A.M.
Deli
1
, N. Slim
1
, B. Noris Chiorda
1
, C.L. Deantoni
1
, C.
Gumina
1
, M. Azizi
1
, G. Rossi
1
, S. Foti
1
, P. Passoni
1
, A.
Bolognesi
1
, N.G. Di Muzio
1
1
San Raffaele Scientific Institute, Department of
Radiotherapy, Milano, Italy
2
San Raffaele Scientific Institute, Medical Physics,
Milano, Italy
Purpose or Objective
To report the local control and soft tissues toxicity, in
breast cancer patients (pts) treated with hypofractionated
adjuvant radiotherapy (HRT), 40 Gy in 15 fractions (2,67
Gy/fraction), after breast conservative surgery (BCS),
with a 5-years median follow-up.
Material and Methods
From February 2009 and October 2011, 442 pts were
treated with HRT after BCS. Local tumor relapse was
defined as recurrence of cancer at irradiated breast. The
acute toxicity was evaluated during RT treatment by RTOG
scale. Late side effects as edema, fibrosis,
hyperpigmentation and telangiectasia, were individually
assessed, using SOMA-LENT score, at 6 months from the
end of radiotherapy and then every year. The association
between possible risk factors and development of early
and late complications was identified using multivariate
logistic regression analysis.
Results
After a median follow-up of 65,4 (12-84,8) mos the rate of
local failure at 5 years was 2,25%. RTOG acute toxicity
was: G0 in 164 pts (37%), G1 in 220 pts (49,8%), G2 in 53
pts (12%) and G3 in 5 pts (1,2%). In 9 pts a delayed toxicity
≥G2 was detected at 1-3 weeks after the end of
radiotherapy. We observed a strong correlation between
acute toxicity ≥G2 and breast volume (p=0,0001), with
best cut-off 866 cc derived from ROC analysis . Another
important correlation was found with chemotherapy
(p=0,003), particularly if concomitant (p=0,017). 99 pts
(22,5%) showed edema and/or hyperpigmentation at 6
months after treatment and then the rate decreased over
time until disappear, without new events. On the
contrary, the rate of pts who presented fibrosis and
telangiectasia was neglectable at 6 months (0,68%) but
increased over time to become 6.5% at 5 years. The use of
build up bolus in more than 7 fractions (p=0,0003), breast
volume (p=0,0006), age<56 years (p=0,021), and previous
axillary dissection (p=0,0004) were the most important
predictable factors for edema and hyperpigmentation,
while the development of fibrosis and telangiectasia was
correlated with acute toxicity (p=0,0115) (Fig. I) and the
presence of edema at 6 months (p=0,0006) (Fig II).
Conclusion
In our experience HRT is a safe treatment with high rate
of 5 year local control, as reported in literature, and low
toxicity. The predicting factors of toxicity emerged from
our analysis could help to better manage the breast HRT
in terms of cosmetic result.
PO-0652 Risk factors for complications of post-
mastectomy radiotherapy on implant-based
reconstructed breast
M. Ogita
1,2
, J. Kawamori
2
, K. Sekiguchi
3
, N. Nagura
4
, R.
In
4
, A. Yoshida
4
, H. Yamauchi
4
, Y. Iwahira
5
1
University of Tokyo Hospital, Radiology, Tokyo, Japan
2
St. Luke’s International Hospital, Radiation Oncology,