Supplementary Material for: Oncoplastic breast conserving surgery: is there a need for standardization? Results of a nationwide survey

Introduction
The NABON Breast Cancer Audit showed that more than 70% of the Dutch women undergoing surgery for breast cancer (BC) maintained their breast contour by breast conserving surgery (BCS) or by immediate reconstruction after ablative surgery. The proportion of oncoplastic surgery applied in patients undergoing breast conserving treatment (BCT) remains unknown. The aim of our study was to assess the need for standardization of oncoplastic breast conserving surgery (OPBCS) in an attempt to enable measurement of the quality of OPBCS.
Methods
To gain a better understanding of current practice in OPBCS we sent a questionnaire to all breast surgeons in the Netherlands who are member of the breast surgery working group (n=134).
Results
A total of 60 breast surgeons, representing different hospitals in the Netherlands, responded. 61.7% of the breast surgeons performed BCS in 60%-100% of their patients. 68.3% responded that BCS was performed using OPS techniques in up to 40% of their patients. OPBCS was defined as level I volume displacement by 45.2% of the breast surgeons and as BCS performed by a breast surgeon and plastic surgeon together by 32.3% of the breast surgeons. 94.5% indicated that there is a need for standardization of the definition of OPBCS in the Netherlands.
Conclusion
This study demonstrates that OPBCS is a major part of daily clinical practice of Dutch breast surgeons treating BC patients. Despite of this, there is no clear definition of OPS in BCT in the Netherlands. Only after standardization, a classification code and quality indicator can be initiated for OPBCS. Ultimately, this will facilitate improvement in quality of BC care.