SLN biopsy for high-risk DCIS patients is a mean of detecting those who may have unrecognized invasive disease and therefore are at risk for distant disease.

Summary Mastectomy probably represents over-treatment for the majority of women with screen detected ductal carcinoma in situ (DCIS) and breast-conserving surgery is now widely advocated. In this study, biopsy cavity shavings were used to ensure Ductal carcinoma in situ (DCIS) has become clinically important only since the advent of routine high-quality mammography, and now accounts for 20-25% of screen-detected breast malignancies (Verbeek et al, 1984). The majority of screen detected DCIS lesions, however, are asymptomatic and impalpable (Gump et al, 1987).Despite the increase in diagnosis, the optimal surgical treatment for DCIS remains controversial. Until recently, DCIS was not differentiated from invasive breast carcinoma and was treated by mastectomy (Price et al, 1989). Since the widespread acceptance of breast-conserving surgery for early invasive breast cancer however, mastectomy is becoming more difficult to justify for localized screen-detected DCIS The main purpose of breast-conserving surgery for invasive or in situ disease is complete excision of the tumour (both macroscopically and microscopically) with a surrounding margin of normal tissue to prevent local recurrence, while maintaining a cosmetically acceptable breast. Unfortunately, there is no regular consensus regarding the definition of complete excision or of an adequate margin of excision. It is clear that the margin of clearance around an invasive tumour correlates with local control rates, with positive resection margins being associated with an increased risk of local recurrence (Veronesi et al, 1990). However, the volume of excised tissue is inversely proportional to the cosmetic outcome (Wazer et al, 1992 (Price et al, 1989).Inadequate excision of the primary lesion appears to be one of the most important causes of local failure after breast-conserving surgery (Silverstein et al, 1994), and new prognostic index for DCIS has been proposed recently that includes resection margins as one of its predictive factors (Silverstein et al, 1996). The Van Nuys prognostic index (VNPI) also quantifies two other predictors of local recurrence, namely DCIS size and pathological classification. A numerical system is used to predict patients more likely to recur after breast conserving surgery.The histological evaluation of excision margins is now known to be a critical part of the assessment of any patient with DCIS being considered for breast-conserving treatment, and various techniques have been used to improve the accuracy, including inking of specimen margins, two-dimensional radiography, cavity shavings and tumour bed biopsies. Biopsy cavity shavings are routinely used in our unit after wide local excision of invasive carcinomas to reduce the incidence of re-excision in patients with the tumour extending close to the main specimen margin.The aim of this study was to determine the effectiveness of using biopsy cavity shavings to ensure complete excision of screen-detected DCIS lesions. PATIENTS AND METHODSScreening mammography is performed at...