A population-based audit of surgical practice and outcomes of oncoplastic breast conservations in Scotland - An analysis of 589 patients.

[INTRODUCTION] Current evidence for oncoplastic breast conservation (OBC) is based on single institutional series. Therefore, we carried out a population-based audit of OBC practice and outcomes in Scotland.

[METHODS] A predefined database of patients treated with OBC was completed retrospectively in all breast units practicing OBC in Scotland.

[RESULTS] 589 patients were included from 11 units. Patients were diagnosed between September 2005 and March 2017. High volume units performed a mean of 19.3 OBCs per year vs. low volume units who did 11.1 (p = 0.012). 23 different surgical techniques were used. High volume units offered a wider range of techniques (8-14) than low volume units (3-6) (p = 0.004). OBC was carried out as a joint operation involving a breast and a plastic surgeon in 389 patients. Immediate contralateral symmetrisation rate was significantly higher when OBC was performed as a joint operation (70.7% vs. not joint operations: 29.8%; p < 0.001). The incomplete excision rate was 10.4% and was significantly higher after surgery for invasive lobular carcinoma (18.9%; p = 0.0292), but was significantly lower after neoadjuvant chemotherapy (3%; p = 0.031). 9.2% of patients developed major complications requiring hospital admission. Overall the complication rate was significantly lower after neoadjuvant chemotherapy (p = 0.035). The 5 year local recurrence rate was 2.7%, which was higher after OBC for DCIS (8.3%) than invasive ductal cancer (1.6%; p = 0.026). 5-year disease-free survival was 91.7%, overall survival was 93.8%, and cancer-specific survival was 96.1%.

[CONCLUSION] This study demonstrated that measured outcomes of OBC in a population-based multi-centre setting can be comparable to the outcomes of large volume single centre series.