Positive anterior margins in breast conserving surgery: Does it matter? A systematic review of the literature.

Positive margins are associated with an increased risk of ipsilateral breast tumor recurrence (IBTR); therefore re-excision of positive margins is recommended. Involvement of anatomically non-breast margins, such as anterior margins, has been associated to a lower risk of IBTR than radial margins. Although many surgeons do not re-excise positive anterior margins (PAM); there is no consensus regarding this approach. The objective of this study is to find evidence that assesses this practice. A systemic literature review was performed through six databases from January 1995 to July 2014. Studies that discussed anatomical location of involved margins in BCS were included. Six studies were identified evaluating PAM. One study reported a 2.5% rate of IBTR in patients with non-negative margins treated with radiotherapy (of which 23% had a PAM). Another study showed 4% of residual disease after re-excision of PAM, but did not report IBTR rates. A later observational study reported that 87.5% of positive anterior and posterior margins were re-excised. One survey from America and one from the UK showed that 47% and 71% of surgeons would not re-excise PAM, respectively. A later survey in the UK reported that 43.8% of surgeons would not re-excise PAM in DCIS, whilst 29.2% would not for invasive carcinoma. Common surgical practices to not re-excise PAM contradict current guidelines that recommend obtaining negative margins to reduce the risk of IBTR. However, there is little evidence detailing the relationship between PAM and IBTR rates. Low residual disease after re-excision of PAM supports the limited benefit of re-excise this margin; however further studies are required to evaluate this topic.