Global variations in the definition and management of multifocal and multicentric breast cancer: the MINIM international survey

Multifocal and multicentric breast cancers (MFMCBCs) have traditionally been considered a contraindication to breast-conserving surgery (BCS) because of concerns about locoregional control.The most common definition of MFMCBC is anatomical, based on the presence of cancer foci either in a single breast quadrant (multifocal) or in more than one (multicentric). Other definitions are based on the distance between tumours, with multifocal tumours defined as being within 2 cm of each other (up to 5 cm in some articles), and multicentric tumours further away.The reported incidence of MFMCBC varies between 4 and 60 per cent, and has increased, possibly owing to improved imaging accuracy resulting in better detection rates. Similarly, BCS rates for MFMCBC have increased over time as a result of the introduction of advanced oncoplastic techniques that allow en bloc resection of all cancer foci while preserving (or even improving) breast cosmesis. These advances in oncoplastic breast surgery, together with the support of the St Gallen expert panel and emerging evidence of no significant difference in disease-free or overall survival between MFMCBC and unifocal cancers, have resulted in changing practice, with many surgeons considering BCS in selected patients. This topic is still, however, debated as other authors have questioned the oncological safety of BCS in this setting because of a lack of RCTs or high-quality prospective cohort studies.