BACKGROUND: Comparative studies suggest that patients treated with oncoplastic breast conservation surgery (OBCS) have similar pathology to patients treated with wide local excision (WLE). However, patients treated with OBCS have never been compared to patients treated with mastectomy. The aim of this study was to identify which control group was comparable to patients undergoing OBCS. METHODS: Commonly reported histopathological variables of patients treated with OBCS, WLE or mastectomy ± immediate reconstruction (Ms ± IR) were compared using Fisher Exact or Chi squared tests. RESULTS: 1000 patients' data were analysed (OBCS: n = 119; WLE: n = 600; Ms ± IR: n = 281). Tumour size was significantly bigger after OBCS than WLE (p < 0.001), but similar to Ms ± IR (p = 0.138). Tumour grade was higher after OBCS than WLE (p < 0.001), but similar to Ms ± IR (p = 0.497). More axillary nodes were involved in patients with OBCS than WLE (p < 0.001), but comparable to Ms ± IR (p = 0.175). ER and PR expressions were lower after OBCS compared to WLE (p = 0.007, p = 0.009), but identical to Ms ± IR (p = 1, p = 0.904 respectively). Differences in application of systemic (neo)adjuvant therapy followed the above trend. CONCLUSION: Striking similarities found between OBCS and mastectomy patients' histopathological results are in sharp contrast with previously published data. This study suggests that oncological outcomes following OBCS should be compared to mastectomy besides WLE.
