Overuse of sentinel lymph node biopsy with breast conserving surgery for clinical DCIS.

Abstract

1125 Background: The National Comprehensive Cancer Network (NCCN) guidelines recommend against sentinel lymph node biopsy (SLNB) for ductal carcinoma in-situ (DCIS) treated with breast conservation surgery (BCS). SLNB is appropriate with mastectomy because it precludes subsequent SLNB if invasive cancer is identified. However, SLNB is commonly performed with BCS for DCIS. We hypothesize SLNB use in the setting of BCS for DCIS varies and may be over used in some cancer centers. Methods: We examined 6,070 cases with initial biopsy showing DCIS presenting to 13 institutions participating in the NCCN Breast Outcomes Database from 1998-2009. Receipt of SLNB was defined as SLNB performed at any point in primary treatment for those with a final diagnosis of DCIS or at the first surgical procedure for those upstaged to invasive cancer. Characteristics of patients who did and did not have SLNB were compared using Chi-square tests. Logistic models adjusting for clinical and pathologic variables were performed to assess factors associated with use of SLNB. Results: Of 3,725 treated with BCS, 778 (20.9%) had SLNB. Among 2,345 treated with mastectomy, 1,484 (63.3%) had SLNB. Within BCS, patients presenting with clinical symptoms (vs. screening detected) were more likely to have SLNB (p=0.0006, OR: 1.76; 95% CI 1.31-2.36). For both groups, presence of comedo necrosis, year of diagnosis, and treating institution were predictors of SLNB (p<0.0001). 1,171 (19.3%) were upstaged from DCIS at initial biopsy to invasive cancer on final pathology. 212 (18.1% invasive cancer group) had positive nodes. Use of SLNB increased over time from 1998-2009 in mastectomy group. Among BCS group, SNLB use decreased over the first half of the study period and then remained stable at approximately 15% across all centers. Conclusions: Although use of SNLB has decreased over time, a substantial percentage of patients undergoing BCS for DCIS receive SNLB. Practices vary considerably across centers. SLNB can be performed as a second procedure for those treated with BCS and identified with invasive cancer, thereby avoiding unnecessary risk of significant morbidity. Breast programs should review their practices to curtail the use of unnecessary surgery for women with DCIS.