The use of sentinel lymph node biopsy in patients undergoing mastectomy for DCIS.

e12572 Background: Current NCCN guidelines do not recommend sentinel node biopsy (SLNB) for the treatment of DCIS, except in the setting of a mastectomy. The extent of utilization of SLNB in patients undergoing mastectomy for DCIS and which factors are associated with a higher likelihood of SLNB use is unknown. The objective of this study is to evaluate the use of SLNB in patients undergoing mastectomy for DCIS and determine predictors of SLNB utilization. Methods: A retrospective cohort analysis was performed using the NCDB. Women diagnosed with DCIS who underwent a unilateral or bilateral mastectomy from 2012-2017 were included. Patient, tumor, and treatment variables were compared between patients who received a SLNB and those who did not. A multivariate logistic regression model was then used to identify factors predictive of SLNB utilization. Results: A total of 29,962 patients met inclusion criteria. Of these, 25,734 (85.9%) underwent SLNB and 4,228 (14.1%) had no surgical axillary staging. Most patients were age 50-69 (52.0%), non-Hispanic white (71.7%), and had private insurance (65.9%). In those who underwent SLNB, only 10 (<0.01%) were found to have nodal involvement. On multivariate analysis, older patients were less likely to receive SLNB ( p<0.05), while those with grade 2 and 3 DCIS were more likely to undergo SLNB (OR 1.4 and 2.2, respectively, p<0.001) (Table). Patients who were treated from 2014-2017 were also more likely to undergo SLNB (OR 1.2, p<0.01) as were patients treated in the Atlantic and West Central United States ( p<0.05). Treatment at a comprehensive community program, academic/research program, or integrated network program were also more likely to undergo SLNB (OR 1.5, 2.1, 2.3 respectively, p<0.001) compared to community programs. Conclusions: Patterns of SLNB utilization in DCIS varied in clinical practice. Given the low rate of nodal involvement in DCIS patients (<0.01%), and with a 5-10% rate of upper extremity lymphedema after SLNB alone, it may be reasonable to omit SLNB in the setting of a mastectomy for DCIS.[Table: see text]