Risk of invasion and axillary lymph node metastasis in ductal carcinoma in situ diagnosed by core-needle biopsy

Background: The aim of the study was to assess the risk of invasion and axillary lymph node metastasis in patients with ductal carcinoma in situ (DCIS) diagnosed by preoperative core-needle biopsy. The data were used to select criteria for patients in whom sentinel node (SN) biopsy might be indicated. Methods: One hundred and seventy-one women with 172 DCIS lesions diagnosed by core-needle biopsy were analysed. Axillary staging was performed by SN biopsy, axillary node sampling, or level 1-2 axillary lymph node dissection. Results: Invasive breast cancer was found in the surgical specimens from 45 tumours (26.2 per cent). Risk factors for invasion were a palpable lesion (odds ratio (OR) 2.95 (95 per cent confidence interval 1.20 to 7.26); P = 0.019), presence of a mass on mammography (OR 3.06 (1.43 to 6.56); P = 0.004), and intermediate (OR 5.81 (1.18 to 28.57); P = 0.030) or poorly differentiated (OR 5.46 (1.17 to 25.64); P = 0.031) tumour grade. Lymph node metastases were found in ten women with DCIS and invasion on final pathology. Factors associated with metastases were age 55 years or less (P = 0.030), invasion of 1.0 cm or more (P < 0.001) and the presence of vascular invasion (P = 0.001). Conclusion: SN biopsy should be considered in women with an initial diagnosis of DCIS on core-needle biopsy who are at risk for invasion; this includes women with a palpable lump, a mass on mammography, and intermediate or poor tumour grade.