Quantifying Potential Error in Painting Breast Excision Specimens

Aim. When excision margins are close or involved following breast conserving surgery, many surgeons will attempt to reexcise the corresponding cavity margin. Margins are ascribed to breast specimens such that six faces are identifiable to the pathologist, a process that may be prone to error at several stages. Methods. An experimental model was designed according to stated criteria in order to answer the research question. Computer software was used to measure the surface areas of experimental surfaces to compare human-painted surfaces with experimental controls. Results. The variability of the hand-painted surfaces was considerable. Thirty percent of hand-painted surfaces were 20% larger or smaller than controls. The mean area of the last surface painted was significantly larger than controls (mean 58996 pixels versus 50096 pixels, CI 1477–16324, ). By chance, each of the six volunteers chose to paint the deep surface last. Conclusion. This study is the first to attempt to quantify the extent of human error in marking imaginary boundaries on a breast excision model and suggests that humans do not make these judgements well, raising questions about the safety of targeting single margins at reexcision. 1. Introduction An enduring debate amongst breast surgeons concerns the adequacy of excision margins for both invasive and in situ carcinoma (DCIS). As yet, no unequivocal consensus has been reached as to what exactly comprises an adequate surgical margin after breast conserving surgery (BCS) [1]. Typically, a specimen is excised and then painted or marked according to a protocol to indicate laterality and boundaries. In theory, the histopathologist receives a specimen that can then be orientated such that the location of any residual disease can be identified. It has been shown that painting specimens at the time of excision are preferable to painting by the pathology department in terms of reexcision rates [2]. While the National Institute for Health and Clinical Excellence (NICE) suggests reexcision of DCIS if the margin is closer than 2？mm, local policies vary as to what is considered an acceptable margin. Surgeons may accept a closer deep margin since the pectoralis fascia is thought to provide and robust anatomical barrier to local spread. At the Royal Devon and Exeter Hospital NHS Trust, policy is to offer reexcision to patients with any margin of invasive cancer within 2？mm and 1？mm for DCIS. Only in special circumstances will reexcision be offered for close deep or superficial margins. It may be, however, that current practice is fundamentally