Number of sentinel lymph nodes (SLN) removed in breast cancer (BC) patients undergoing sentinel lymph node biopsy (SLNB) in the province of Saskatchewan, Canada: Real-world experience.

Abstract

e19240 Background: SLNB is considered standard of care for BC patient's undergoing surgery. This standard of care is based on several randomized, prospective clinical trials showing non inferiority of this procedure compared to full axillary lymph node dissection (FALND). Retrieval of less than 3 lymph nodes at the time of SLN biopsy has been shown to be associated with decrease in disease specific survival. In the NSABP B-32 study, removal of two SLN rather than one almost halved the false negative rate. SK has an area of 651,900 square kilometer, with a small population of 1,098,352. This population is widely distributed throughout the province with variable access to health care. This study provides us with a unique opportunity to see if data obtained in clinical trials can be replicated in community settings. Methods: After approval from SK Cancer Agency and research ethics board of University of SK. Female Patient’s with BC who underwent SLNB from Jan 2010 to Dec 2014, were identified using cancer registry. 529 charts were reviewed retrospectively. Exclusion criteria’s were Male BC, pathology other than invasive ductal or lobular, locally advanced or metastatic disease, T4 tumors, patients who received neo adjuvant therapy, patients who had declined or were unable to receive post-operative recommended adjuvant systemic or radiation therapy, patients with full axillary lymph node dissection. Data was analyzed using SAS 9.4 software. Results: Rate of 1, 2 and 3 or more SLN was 21, 35 and 44% respectively. The median number of lymph nodes retrieved were 2. 14% of patients had positive lymph nodes. 259/529 (48.9 %) of patients used both vital blue dye and radiotracer method for detection of SLN. In 510/529 (96.4%) radiotracer method was used to detect lymph nodes. Blue dye was used in 264/529 (49.9%). Median number of SLN retrieved using both methods were 2. No change in median number of SNL retrieved in different quadrants and central part of the breast were noted, the number remained 2. Conclusions: Our review showed that rate of single lymph node retrieval was lower than what is reported in US SEER data base study of 37%, however the number of median lymph node retrieval was 2 which is considered less than optimal with reported higher rate of false negative rate. We did not attempt to look at disease-specific survival as our sample size is small. Continued data evaluation of established practice is required to improve quality of care and replication of advances established in clinical trials.