Targeted Intraoperative Radiotherapy Tumour Bed Boost During Breast Conserving Surgery after Neoadjuvant Chemotherapy in HER2 Positive and Triple Negative Breast Cancer.
Targeted intraoperative radiotherapy (TARGIT - IORT) as a tumour bed boost after breast conserving surgery is well established for women with early breast cancer. A previous study from our group shows a beneficial effect of TARGIT-IORT on overall survival (OS) but not disease-free survival (DFS) after neoadjuvant chemotherapy compared to an external boost suggesting a potential non-inferiority of TARGIT-IORT. In this study, we present results regarding the high-risk subset of patients (i.e. with triple negative (TN) and HER2 positive tumours) from this cohort.



In this non-randomized cohort study involving patients with HER2 positive (n= 28) and triple negative (n=42) tumours after NACT we compared outcomes of 40 patients with tumour bed boost applied with TARGIT IORT during lumpectomy versus 30 patients treated in the previous 13 months with external (EBRT) boost. All patients received whole breast radiotherapy. Rates of DFS and OS were compared.



Median follow up was 49 months. In comparison of TARGIT-IORT vs. EBRT 5-year Kaplan- Meier estimates of OS showed no significant difference among patients with HER2 positive tumours (100% vs. 91.7%, log rank p = 0.22). The same was seen for DFS (83.3% vs. 77.0%, log rank p=0.38). The results for TN cases were similar (OS : 87.5% vs. 74.1%, log rank p=0.488; DFS 87.5% vs. 60%, log rank p=0.22).



Although survival estimates trended towards favouring TARGIT-IORT, no significant differences could be observed and the significantly positive result for OS favoring TARGIT-IORT in the whole cohort of 116 patients could not be reproduced in this subset analysis of patients with TN and HER2 positive tumours. This may be contributable to the limited number of patients but may also indicate that effects seen in the whole cohort were mainly driven by ER and/or PR positive and HER2 negative tumours. Most importantly, non-inferiority of TARGIT-IORT as an intraoperative boost could be reproduced in these high-risk patients.
Department of Gynecology and Obstetrics, Marienhospital Bottrop gGmbH, Josef-Albers-Str. 70, 46236 Bottrop, Germany.
Hans-Christian
HC
Kolberg
BORAD, Neustr. 17a, 46236 Bottrop, Germany.
Gyoergy
G
Loevey
BORAD, Neustr. 17a, 46236 Bottrop, Germany.
Leyla
L
Akpolat-Basci
Marienhospital Bottrop, Josef-Albers-Str. 70, 46236 Bottrop, Germany.
Miltiades
M
Stephanou
University of Erlangen, Ulmenweg 18, 91054 Erlangen, Germany.
Peter A
PA
Fasching
Helios Klinikum Berlin-Buch, Schwanebecker Chaussee 50, 13125 Berlin, Germany.
Michael
M
Untch
University of Notre Dame, 32 Mouat St, Fremantle WA 6959, Australia.
Max
M
Bulsara
University College London, 235 Euston Rd, Fitzrovia, London NW1 2BU, United Kingdom.
Jayant S
JS
Vaidya
University Hospital Schleswig- Holstein/ Campus Luebeck, Ratzeburger Alle 160, 23538 Luebeck, Germany.
Cornelia
C
Liedtke
D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant; D016009:Chi-Square Distribution; D015331:Cohort Studies; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D053208:Kaplan-Meier Estimate; D015412:Mastectomy, Segmental / Q000379:methods*; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D009367:Neoplasm Staging; D011379:Prognosis; D000069473:Radiation Dose Hypofractionation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000187:drug effects / Q000528:radiation effects*; D012189:Retrospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D016896:Treatment Outcome; D064726:Triple Negative Breast Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy*
D018719:Erb-b2 Receptor Tyrosine Kinases
Breast cancer; HER2-positive; TARGIT-
IORT; breast conserving surgery; intraoperative radiotherapy; neoadjuvant therapy; triple negative