358 / 1082
S343
ESTRO 36 2017
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Conclusion
Hypofractionated hybrid FiF+VMAT SIB showed to be
feasible and was associated with low acute toxicity
burden. 1-year follow-up data demonstrated a noticeable
decline in radiotherapy related QoL items.Long-term
results are needed to assess late toxicity and clinical
outcome.
PO-0664 Standardized Nodal Radiation (RT) through a
Breast Clinical Pathway (CP) within a USA Cancer
Network
B. Gebhardt
1
, Z. Horne
1
, G. Ahrendt
2
, E. Diego
2
, D.
Heron
1
, S. Beriwal
2
1
University of Pittsburgh Cancer Institute, Radiation
Oncology, Pittsburgh, USA
2
University of Pittsburgh Cancer Institute, Surgical
Oncology, Pittsburgh, USA
Purpose or Objective
ACOSOG Z11 and EORTC AMAROS studies investigated
patients (pts) with clinical T1-2 N0 invasive breast cancer
(IBC) undergoing breast conserving surgery (BCS) with
positive sentinel node (+SLN) biopsy and demonstrated the
safety of omitting axillary nodal dissection (ALND).
Adjuvant RT fields employed differed between the two
trials as regional nodal irradiation (RNI) was mandated in
AMAROS and RT fields were heterogeneous in Z11.
Furthermore, MA-20 and EORTC RNI trials demonstrated a
survival benefit with RNI in pts with positive nodes,
leading to wide variation in RT treatment volumes. CPs
standardize care when many therapeutic options exist and
clinical practice varies unnecessarily. We sought to
evaluate the impact of changes to a CP guiding adjuvant
RT in pts with +SLNs on practice patterns throughout a
large, integrated cancer network.
Material and Methods
We implemented a CP for management of IBC with
adjuvant RT throughout a network of 22 centers that
required entry of management decisions into an online
support tool. The CP for treatment of pts with +SLN
following BCS was modified in February 2015 to promote
uniform treatment of nodal volumes. The CP
recommended modified tangents (MT) including level I/II
nodes for pts with micrometastases (pN1mi). For pts with
macrometastases (pN1a), CP recommended including level
I/II LN in MT and additional field to include level III,
supraclavicular (SCV) LN +/- internal mammary nodes for
pts with any adverse factor including T2 disease, LVSI,
high grade, ER negative, ECE, or age <50. Adjuvant RT
fields of pts undergoing BCS with +SLN but not ALND were
retrospectively reviewed.
Results
The RT fields of 257 pts from July 2011 to August 2016
were reviewed, including 74 (29%) with pN1mi disease &
183 (71%) with pN1a. Of 127 pts treated prior to CP
changes, 13 (24%) of 37 pts with pN1mi were treated with
whole breast irradiation (WBI) alone and 18 (20%) of 90 pts
with pN1a with WBI alone. Following CP changes, 130 pts
were treated, including 5 (4%) pts treated with WBI alone,
63 (49%) with MT, and 62 (48%) MT + SCV field. Of 37 pN1mi
pts, 3 (8%) were treated with WBI alone. Of 92 pN1a pts,
1 (1%) was treated with WBI alone. A summary of
treatment fields relative to pathway change is included in
Figure 1
. On multivariable analysis (MVA), pN1a disease
and treatment after CP changes were associated with use
of MT
(Table 1)
. Use of SCV field was associated with pN1a
disease with adverse factors and treatment after CP
changes.
Conclusion
CP’s are useful tools for translating published research and
guidelines into pt management plans to promote
evidence-based care and eliminate unnecessary variations
in practice. Recognizing that adjuvant RT treatment
volumes were heterogeneous following the publication of
Z11 and AMAROS, we modified the CP in 2015 based upon
the latest evidence for RNI. After the amendment, pts
received standardized RT fields guided by the CP based
upon clinical risk factors which will aid in tracking
outcomes in future investigations.