But how to treat those with positive SLNB? Results and Discussion The Role of Sentinel Lymph Node Biopsy in Patients with Ductal Carcinoma in Situ. An Updated Meta-Analysis Involving 9803 Patients Hiba El Hage Chehade, Hannah Headon, Umar Wazir, Abdul Kasem and Professor Kefah Mokbel The London Breast Institute, Princess Grace Hospital Background Pre-operative group Post-operative group Isolated tumor cells 24.4% 33.95% Micrometastasis 48.5% 27.3% Macrometastasis 23.1% 26.2% Other studies have found other characteristics to be associated with a positive SLNB Ductal carcinoma in situ (DCIS) is the predominant noninvasive breast cancer in the UK accounting for 83% of all in situ breast cancers diagnosed. Current treatment comprises wide local excision or mastectomy +/- radiotherapy. By definition, it is noninvasive, so there should be no spread to the axillary lymph nodes. However, some studies have reported that some patients with DCIS harbour an invasive component. The current ASCO guidelines state that SLNB should be performed for DCIS in two circumstances: 1) in patients undergoing mastectomy, 2) as a second-stage SLNB if an invasive component was found on histological analysis of the tumour following breast conserving surgery (BCS). However, it is unclear whether there is a role for a routine SLNB in DCIS patients undergoing BCS. Clinically occult invasion Previous studies have found associations between features of high grade DCIS, such as opacity on mammogram and palpable tumours, and subsequent detection of invasion. Age at diagnosis Younger women are more likely to harbour invasive disease younger patients with DCIS should be considered for SLNB. Not all studies reported the incidence of isolated tumour cells; therefore, this should be interpreted with caution. Significant heterogeneity between studies was observed Preoperative diagnosis I2 80.7% Postoperative diagnosis I2 65.7%  a random effects model was adopted, and pooled estimate of positive SLNB of 5.3% and 3.0% were reported in the pre and post-operative diagnosis respectively Palpability of the tumor Methods Receptor status A literature search was performed using PubMed and Ovid databases. Inclusion criteria comprised female patients with a diagnosis of DCIS who underwent SLNB as part of their management Exclusion criteria included studies that: 1) did not report on the number of positive SLNB results; 2) did not specify whether the diagnosis of DCIS was made pre- or postoperatively; 3) were letters, commentaries or reviews. Separate analyses were performed based on whether the diagnosis of DCIS was given pre- or postoperatively. Included ANOVA analysis, Cochran’s Q test for the null hypothesis, forest plots were constructed to calculate pooled estimates with 95% confidence intervals and I2 test was performed for heterogeneity. But how to treat those with positive SLNB? Most common findings are isolated tumour cells or micrometastases. The ASCO guidelines indicate that clinicians should not recommend axillary lymph node dissection with early breast cancer patients who have one or two sentinel lymph node metastases and receive BCS and radiotherapy Multidisciplinary team decisions needed. Results and Discussion 48 articles were identified yielding a total of 9803 patients. Primary endpoint: % of patients with a positive SLNB DCIS patients undergoing BCS Pre-operative diagnosis with DCIS 5.95% Post-operative diagnosis with DCIS 3.02% Conclusion To our knowledge, this is the largest analysis to date for the use of the SLNB in DCIS. SLNB should be routinely considered in patients with large (>2cm) high grade DCIS. In the context of BCS, the SLNB is not routinely indicated for low and intermediate grade DCIS, high grade DCIS smaller than 2 cm, or pure DCIS diagnosed by definitive surgical excision. Furthermore, we believe that the clinical effect of such selective SLNB for DCIS would be an important area of research for future prospective studies and randomised trials, as this would enable better informed decisions in the treatment of DCIS. Funnel plots showed evidence of publication bias in both groups leading to adjusted estimates of 7.3% in the preopertively diagnosed group and 3.7% in the postoperative cohort. Secondary endpoint: who would benefit most from SLNB in DCIS? Meta-regression indicated that tumour size (p=0.033) and high grade tumours (p=0.0084) were associated with SLNB positivity  The incidence in the preoperatively diagnosed group was significantly higher (p=0.02)