Are mastectomy resection margins of clinical relevance? A systematic review

Although some guidelines support the use of post-mastectomy radiotherapy where the resection margin is involved or close, the scientific basis of this practice is not established. This systematic review explores the relationship between margin status and subsequent relapse. Pooled data from 22 studies (18,863 women) identified an involved post-mastectomy margin in 2.5%, a close margin in 8.0% and muscle or fascia invasion in 7.2% of patients. In a meta-analysis of five studies of non-inflammatory breast cancer without radiotherapy, local recurrence was increased by an involved or close margin (relative risk 2.6; P<0.00001). The effect of muscle or fascia invasion was of borderline significance (relative risk 1.7; P=0.04). In two separate meta-analyses, risk of relapse was related to margin status in women with inflammatory breast cancer (relative risk 3.1; P<0.0001) but not in those undergoing skin-sparing mastectomy (relative risk 2.1; P=0.16).