Evaluating the current evidence to support therapeutic mammoplasty or breast-conserving surgery as an alternative to mastectomy in the treatment of multifocal and multicentric breast cancers

The oncological safety of treating multiple ipsilateral breast cancers (MIBCs) with types of breast conserving surgery (BCS) compared to mastectomy remains uncertain. This is predicated on the absence of any randomised controlled trials or high-quality protocol defined prospective cohort studies. A single recently published systematic review by the first author, reports its summarised results in this review. Fundamentally the important question is the evaluation of clinical safety following BCS compared to mastectomy for treating MIBC, which is reported in only six studies. Consequently, current evidence doesn’t support the latest St Gallen consensus suggesting the possibility of using BCS to treat all MIBC. There is minimal comparative outcomes data on multicentric (MC) cancers compared to multifocal (MF) cancers comparing BCS or mastectomy. There is also poor evidence of clinical outcomes following therapeutic mammoplasty (TM) for MIBC compared to mastectomy. The potential recommendation of two potential radiotherapy boosts to separate lumpectomy sites following BCS for MC cancers remains a novel treatment concept whose feasibility will be evaluated in the forthcoming NIHR funded randomised feasibility trial called MIAMI. This is a world first attempt to assess the feasibility of a randomised trial design alongside the on-going Alliance registry study (ACOSOG, American College of Surgeons Oncology Group Z11102) in the USA, in which there is no comparative evaluation of mastectomy outcomes. The MIAMI trial aims to assess the clinical safety of multiple lumpectomies combined with TM compared to the standard of mastectomy in MIBC stratified by MF or MC cancers. There is limited evidence on the impacts of inter-tumoral heterogeneity relating to breast cancer subtypes in relation to individualised treatments and recommendations for types of breast surgery. Recent studies have highlighted the potential contributions of stromal epigenetic changes that are currently poorly understood regarding their contributions to either clinical unifocal or MF cancers.