Re-irradiation and hyperthermia for locoregional recurrent breast cancer: Outcome of 23x2Gy vs 8x4Gy
Akke Bakker,
The Netherlands
MO-0798
Abstract
Re-irradiation and hyperthermia for locoregional recurrent breast cancer: Outcome of 23x2Gy vs 8x4Gy
Authors: Akke Bakker1, C. Paola Tello Valverde1, Geertjan van Tienhoven1, M. Willemijn Kolff1, H. Petra Kok1, Ben J. Slotman1, Inge R.H.M. Konings2, Arlene L. Oei3, Hester S.A. Oldenburg4, Emiel J.T. Rutgers4, Coen R.N. Rasch5, H.J.G. Desirée van den Bongard1, Hans Crezee1
1Amsterdam UMC, Department of Radiation Oncology, Cancer Center Amsterdam, Amsterdam, The Netherlands; 2Amsterdam UMC, Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam, The Netherlands; 3Amsterdam UMC, Laboratory for Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Cancer Center Amsterdam, Amsterdam, The Netherlands; 4Netherlands Cancer Institute, Department of Surgical Oncology, Amsterdam, The Netherlands; 5LUMC, Department of Radiation Oncology, Leiden, The Netherlands
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Purpose or Objective
Operable patients with locoregional (LR) recurrent breast cancer at high
risk for re-recurrence are treated with postoperative re-irradiation combined
with hyperthermia (HT), i.e. heating the target area to 40-43 °C for one hour,
in the Netherlands. Early 2015, national consensus was reached using a new standard
RT dose fractionation schedule of 23x2Gy, replacing the 8x4Gy RT schedule used in
our center. We investigated the impact of both postoperative re-irradiation schedules
on LR
control and late toxicity in patients with LR recurrent breast cancer treated at
our center
Material and Methods
In this retrospective study, 112 women with resected LR recurrent breast
cancer treated in 2010-2017 with postoperative re-irradiation combined with 4-5
weekly HT sessions were included. RT treatment consisted of 8x4Gy (n=34, twice
a week) until 2014, or 23x2Gy (n=78, 5 times a week) after 2014. Due to frailty
or long travel distance 5 patients received 8x4Gy after 2014. Re-irradiation
was delivered using 3 consecutive different RT planning techniques. From
2010 to mid-2014 the lateral chest wall and/or regional lymph nodes areas were
irradiated using two opposing AP-PA fields and the anterior chest wall with
electrons, the breast was treated with two tangential fields. From mid-2014
IMRT was applied using 5-7 beam angles, and from early 2016 onward VMAT using
two (counter)clockwise partial arcs.
Actuarial LR control and grade 2-5 late toxicity incidence (>3 months
after the first re-irradiation fraction) were analyzed. Toxicity was defined according to CTC-AE v5.0. Patients had multiple late toxicities. The
cause of late toxicity might be current or previous treatments or an cumulative
effect. Backward multivariable Cox regression was performed.
Results
Twenty-four patients (21.4%) developed an in-field
recurrence. Median FU was 43 months (range 1-107 months). Three-year LR control was 89.4% vs. 68.7% in the 23x2Gy
and 8x4Gy group, respectively (p=0.01),
LR control tended to be better for the 23x2Gy group after long FU (p=0.094; Fig 1A).istant metastasis (HR 17.6;
95%CI 5.2-60.2), lymph node involvement (HR 2.9; 95%CI 1.2-7.2), recurrence site (chest wall vs. breast; HR 4.6; 95%CI 1.8-11.6) and thermal dose
(low vs. high; HR 4.1; 95%CI 1.4-11.5) were
associated with LR control. Three-year late grade 2, 3 and 4 toxicity was 63%, 39% and 0% vs. 54%,
19% and 8% for 23x2Gy and 8x4Gy groups, respectively. No grade 5 late toxicity occurred. The 23x2Gy group had a trend for more
grade 3-4 late toxicity (p=0.064, Fig1B).
Conclusion
Patients with LR recurrent breast cancer treated with 23x2Gy postoperative
re-irradiation and HT tended to have better LR control at the cost of higher
incidence of grade 3-4 late toxicity compared to patients treated with 8x4Gy.
Fig 1. Kaplan-Meier survival analysis for A)
LR control, B) grade 3-4 late toxicity for patients treated with 8x4Gy and 23x2Gy
postoperative re-irradiation and HT for LR recurrent breast cancer.