Residual tumour after biopsy for non-palpable ductal carcinoma in situ of the breast

In a group of 40 patients with non‐palpable ductal carcinoma in situ (DCIS) of the breast, 41 breast specimens were available for studying residual tumour after biopsy. In one group of ten patients seen before 1977, simple histological examination revealed a 9 per cent incidence of residual tumour. However, after thorough examination residual foci of DCIS were found in 77 per cent of a subsequent group of 30 patients. This means that the majority of patients would have had to undergo reoperation if a breast‐saving procedure had been performed. This fact must be taken into account when planning treatment of patients with non‐palpable DCIS.