2 mm plus radiotherapy is as good as a bigger margin

The widespread use of mammography screening has led to a change in the perceived pathology of breast cancer. The increased detection of asymptomatic disease has resulted in an increased incidence of ductal carcinoma in situ (DCIS), which now accounts for about 20% of all cases of breast cancer. In addition, the past decade has seen a change in the management of primary breast cancer, from mastectomy to breast conservation where possible.1 Clearly surgical management of DCIS poses several challenges, none more so than what should be the width of an adequate margin of resection. What is at issue is the size of the margin that ensures no residual tumour cells while minimising the deformity of the breast.

The National Surgical Adjuvant Breast and Bowel Project (NSABP) regards “no tumour cells on the ink”—that is, a minimal margin free of disease—as a negative margin. Yet in a recent survey of 1137 radiation oncologists only 45.9% of North American respondents and 27.6% of Europeans agreed with this definition.2 When this margin was extended to 2 mm over 75% of North American respondents agreed that this could be regarded as negative, …