The Superficial (Anterior) Plane in Mastectomy: An Under-Measured Margin Variable with Implications for Local Recurrence.

The anterior (superficial) aspect of the mastectomy specimen is often treated as an anatomical boundary rather than a true resection margin. However, pathology sampling studies demonstrate that benign breast epithelium/residual breast tissue can be present at the superficial dissection plane when actively sought [e.g., benign ducts identified in 53% of additional superficial margin specimens after skin-sparing mastectomy (Cao et al. in Ann Surg Oncol 15(5):1372-1377, 2008) and residual breast tissue detected in 76.2% of intensively sampled mastectomy specimens (Griepsma et al. in Ann Surg Oncol 21(4):1260-1266, 2014)]. In parallel, recurrence mapping data indicate that most postmastectomy local recurrences occur superficially [81.8% in skin/subcutaneous tissues (Kaidar-Person et al. in Breast Cancer Res Treat 183(2):263-273, 2020)], and systematic evidence shows that involved/close margins are associated with higher local recurrence risk [pooled hazard ratio (HR) 2.64; skin-sparing mastectomy HR 3.40 (Bundred et al. in Eur J Surg Oncol 46(12):2185-2194, 2020)]. Despite these converging observations, the literature has not tested whether local recurrence risk differs when the superficial plane consists of skin/fat only versus fibroglandular tissue present. We propose a pragmatic, low-burden addition to clinical and database toolboxes: standardized pathology documentation of superficial-plane tissue composition (present/absent; optionally focal versus multifocal). This would enable retrospective analyses and prospective multicenter studies to determine whether the superficial plane behaves as an anatomical boundary or a clinically meaningful resection margin.