Role of sentinel lymph node biopsy in patients with ductal carcinoma in situ and microinvasion

Abstract

Aim: Ductal carcinoma in situ with microinvasion (DCISMI) is characterized by one or more areas of focal invasion, 1 mm or less in diameter. While pure ductal carcinoma in situ (DCIS) does not have the potential to metastasize to regional nodes, the presence of microinvasion makes lymph node metastasis possible, leading to current guidelines recommending staging of the axilla with sentinel lymph node biopsy (SLNB). However, there are few studies looking at the risk of lymphatic spread in patients with DCISMI, and indications for axillary staging in such cases is controversial. The aim of the present study was to assess the prevalence of nodal metastasis in patients with DCISMI in order to help ascertain whether SLNB can be safely avoided in DCISMI.Patients and Methods: A retrospective analysis was performed of patients undergoing surgery for DCIS over a 2‐year period (April 2006–08). Data were collected from the National Health Service Breast Screening Programme database and patient case notes. Patients having a SLNB had injection of radioisotope and blue dye. All SLNB were evaluated with serial sectioning and haematoxylin–eosin staining.Results: Over the 2‐year period, 399 screen‐detected breast cancers were treated, of which 310 (77 per cent) were invasive, 17 (4 per cent) had DCISMI and 72 (19 per cent) pure DCIS. The group with DCISMI was studied in more detail. Twelve out of the 17 patients had a wide local excision and five had a mastectomy. All 17 patients with DCISMI had a SLNB. No positive lymph nodes were found in this group.Conclusion: Our data suggest that the risk of nodal metastasis in DCISMI might be low, and question the role of SLNB in DCISMI. We highlight the lack of data on DCISMI and risk of nodal metastasis, and the need for further investigation.