Stereotactic body RT (SBRT) and concomitant systemic therapy in oligoprogressive breast cancer
PO-1188
Abstract
Stereotactic body RT (SBRT) and concomitant systemic therapy in oligoprogressive breast cancer
Authors: Luca Nicosia1, Vanessa Figlia1, Nicola Ricottone2, Francesco Cuccia3, Rosario Mazzola1, Niccolò Giaj-Levra1, Francesco Ricchetti1, Michele Rigo1, Andrea Girlando4, Filippo Alongi1
1IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, Negrar, Italy; 2Istituto Clinico Catanese, Unità operativa di Radioterapia Humanitas, Catania, Italy; 3IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, N egrar, Italy; 4IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, Catania, Italy
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Purpose or Objective
breast cancer is a heterogenous disease with a deep
tailoring level. Evidence are accumulating on the role of stereotactic body
radiotherapy (SBRT) in the management of oligometastatic disease. While in
other histology there is a large amount of data, the evidence in
oligometastatic breast cancer is limited. The aim of the present study is to
show the effectiveness of SBRT in delaying the switch to a subsequent systemic
treatment line in oligoprogressive breast cancer patients.
Material and Methods
retrospective
analysis from two Institutions. The primary end-point was time to next systemic
treatment (NEST). Secondary end-points were freedom from local progression
(FLP), time to the polymetastatic conversion (tPMC) and overall survival (OS).
Results
One-hundred fifty-three (153) metastases in 79
oligoprogressive breast cancer patients were treated with SBRT. The median
follow-up was 24 months. The median NEST was 8 months. Factors predictive of
NEST at the multivariate analysis (MVA) was the number of treated
oligometastases (HR 1.765, 95%CI 1.322-2.355; p=0.00). Systemic treatment after
SBRT was changed in 29 patients for polymetastatic progression and in 10
patients for oligometastatic progression <6 months after SBRT. The 2-year
FLP in the overall population was 86.7%. A biological effective dose (BED)
>70Gy10 was associated with improved FLP (90% versus 74.2%). The median tPMC
was 10 months. At the MVA the only factors significantly associated with tPMC
were the number of oligometastases (HR 1.172, 95%CI
1.000-1.368; p=0.03), and the local control of the treated
metastases (HR 2.726, CI95% 1.108-6.706; p=0.02).
Conclusion
SBRT can delay the switch to a subsequent systemic
treatment, however patient’s selection is necessary. Several predictive factors
for treatment tailoring were identified.