Specimen shrinkage and its influence on margin assessment in breast cancer.

OBJECTIVE: The determination of tumour-free margin in breast cancer is crucial in deciding subsequent patient management. To exemplify the phenomenon of margin contraction during specimen preparation for histopathological analysis, we quantified the shrinkage of breast specimens as a result of formalin fixation. METHODS: Fifty consecutive mastectomy and wide excision specimens were prospectively appraised. The closest free margin and maximal tumour diameter of fresh, unprepared specimens were recorded. These measurements were compared with the corresponding parameters following tissue fixation. RESULTS: Following formalin fixation, the mean closest free margin of the specimens was found to have decreased from 10.28 mm to 6.78 mm (34%). The reduction of the mean diameter of the tumour itself was less significant, from 41.74 mm to 39.88 mm (4.5%). CONCLUSION: Breast specimens undergo shrinkage after histological fixation, losing more than a third of their original closest free margin, whilst the tumour itself does not shrink substantially. This phenomenon has vital implications in the accuracy of margin analysis and consequent decisions on further management, including re-operation and the institution of adjuvant radiotherapy.