Ultra-hypofractionated whole breast radiotherapy with integrated boost for early breast cancer
PO-1135
Abstract
Ultra-hypofractionated whole breast radiotherapy with integrated boost for early breast cancer
Authors: Angel Montero1, Raquel Ciervide1, Mariola Garcia-Aranda1, Beatriz Alvarez1, Alejandro Prado2, Xin Chen-Zhao1, Rosa Alonso1, Mercedes Lopez1, Emilio Sanchez1, Ovidio Hernando1, Jeannette Valero1, Monica Nuñez1, Marta Izquierdo1, Karla Rossi1, Carmen Cañadillas1, Pedro Fernandez-Leton2, Carmen Rubio1
1HM Hospitales, Radiation Oncology, Madrid, Spain; 2HM Hospitales, Medical Physics, Madrid, Spain
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Purpose or Objective
Whole breast irradiation
(WBI) after breast conserving surgery (BCS) is indicated to improve
loco-regional control and survival. Former studies showed that addition of
tumor bed boost in all age groups significantly improved local control although
no apparent impact on overall survival but with an increased risk of worse cosmetic
outcome.
Although hypofractioned
regimens in 3 weeks are considered the standard, recent studies have shown the
non-inferiority of a treatment regimen of 5 fractions in one-week in both locoregional
control and toxicity profile. We present our preliminary results of acute toxicity
of a ultra-hypofractionated 5 fractions in one-week WBI schedule with simultaneous
integrated boost (SIB) in early breast cancer.
Material and Methods
FromMarch-2020
to January-2021, 138 patients with a median age of 58.5years (range 31-87) were
treated according to our institution ultra-hypofractionated radiotherapy schedule
after breast conserving surgery (BCS).Clinical staging (AJCC): Tis 29p (21%) ,
T1a 10p (7.5%), T1b% 36p (26%), T1c 54p (39%), T2 9p (6.5%). All patients were
pN0
Radiotherapy comprises
whole breast receiving 26Gy@5.2Gy/day with a simultaneous integrated boost (SIB) to all patients up to a
total dose of 29Gy@5.8Gy/day in 111p (80%) and 30Gy@6Gy/day in 27p (20%) with close/focally
affected margins. WBI+SIB was delivered by conformal 3-D technique in 130p
(94%), VMAT in 6p (4%) and 3-D with deep inspiration breath hold (DIBH) in 2p
(1.5%).Treatment beam arrangement for SIB comprised of coplanar 2 beams in 1p (1%),
3 beams in 43p (31%), 4 beams in 77p (56%), 5 beams in 11p (8%) and 2 arcs in 6p
(4%). Dose constraints are detailed in table 1
Systemic therapy:
136p (98.5%) received hormone therapy and 12p (9%) systemic or targeted chemotherapy.
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OAR
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Ipsilateral lung
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V12<20%
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Contralateral
lung
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Dmean<5.6 Gy
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V3.6 <10%
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Heart
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V12 <5%
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V7<5%
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V1.5 < 30%
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Contralateral
Breast
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V3.6 < 30 %
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Spinal Canal
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Dmax< 27 Gy
D0.01 cc< 22.5 Gy
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OAR: organs at risk;, Dmean: mean dose; Dmax: maximal dose
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Results
With a median
follow-up of 3.5months (range1-11), acute tolerance was acceptable with null o
mild toxicity: 69p (50%) developed skin toxicity grade 1 and 3p (2%) grade 2.
No other acute toxicities were observed
A comparative analysis
was performed with the Chi-Square test. We found a weak but significant relation
between age (< 56 years-old) and dermitis G1-2 (p = 0,048), however w3e
could not demonstrate any relation with use of chemotherapy (p = 0.33), homonotherapy (p =
0.06), breast PTV ( p = 0.12), boost PTV (p = 0.47) or ratio boost PTV/breast
PTV (p = 0.27) and tolerance.
Conclusion
Ultra-hypofractionated
WBI with SIB in 5 fractions along one-week is feasible and well tolerated although
longer follow-up is necessary to confirm these results.