Role of Sentinel Lymph Node Biopsy in Ductal Carcinoma In Situ: Diagnosis and Methodology

Abstract

During the past decade, sentinel lymph node (SLN) biopsy has become well established as a new standard for axillary node staging in early stage invasive breast cancer. Since the initial reports of SLN mapping by Krag et al. (1993) (using radioisotope), Giuliano et al. (1994) (using blue dye), and Albertini et al. (1996) (using a combination of isotope and dye), four randomized trials (Veronesi et al., 2003; Mansel et al., 2006; Purushotham et al., 2005; Krag et al., 2007) and 69 observational studies (Kim et al., 2006) of SLN biopsy validated by a completion axillary dissection (ALND) have established that SLN biopsy is feasible, accurate and safe. Ductal carcinoma in situ (DCIS) currently accounts for ~ 20% of all screen detected breast cancers (UK NHSBSP 2005–2006). By definition, DCIS is not an invasive malignancy and does not have the ability to metastasize to regional lymph nodes. Axillary dissection is contraindicated in DCIS because of the low (1%) incidence of lymph node metastasis using conventional hematoxylin and eosin (HE Yiangou et al., 1999). The 5 year relative survival for DCIS is higher than 100%. Moreover, the lower limits of the 95% confidence intervals for the 5 year relative survival of women with DCIS are > 100%. This indicates that their chance of survival is no worse than that of the general female population as a whole (UK NHSBSP 2005–2006). Given this background, SLN biopsy in all patients with DCIS cannot be justified. As we have previously argued (Goyal et al., 2006), the justification for SLN biopsy in DCIS is diagnostic uncertainty. Core needle biopsy has an inherent sampling error leading to histologic underestimation of invasive disease. United States based series have a lower underestimation rate because of higher open biopsy rates compared with European series. UK 2005/06 NHS Breast Screening Programme audit data combined with that of many others supports an emerging consensus that in ~ 20% of patients with a B5a (non-invasive) non-operative diagnosis, invasive disease is found at surgery (UK NHSBSP 2005–2006). 47 Role of Sentinel Lymph Node Biopsy in Ductal Carcinoma In Situ: Diagnosis and Methodology