Sentinel Lymph Node Biopsy After Initial Lumpectomy (SNAIL Study)-a Prospective Validation Study

Tertiary oncology center clinicians are commonly faced with the problem of managing patients with a diagnosis of breast cancer made after lumpectomy in the Primary Health Care (PHC) setting. There are no studies or guidelines that address the further surgical management in this group of patients regarding sentinel lymph node biopsy (SLNB) and need for breast post-operative cavity excision. Prospective observational study was planned to evaluate the feasibility of SLNB and defining the need for definitive breast surgery in patients diagnosed with breast cancer after lumpectomy in PHC. The study was carried out from January 2015 to August 2017 in Tata Medical Center, India, approved by institutional review board (EC/TMC/36/14). Seventy patients who underwent lumpectomy with a definitive histological analysis of breast cancer were included in this study. Each patient had definitive breast surgery and SLNB using subareoral blue dye injection followed by validation axillary dissection. The identification rate (IR) for SLNB was 92% (64/70). The median number of SLNs removed was 2 (IQR 1, 3). There were 2 patients with false negative results resulting in false negative rate (FNR) of 11%. Overall, SLNB procedure has the sensitivity of 89%, NPV of 96%, and accuracy was 97%. Peri-areoral incision of initial surgery was associated with low IR (84%) and high FNR (33%). Final histopathology showed residual invasive cancer in 43% and ductal carcinoma in situ in 14% of patients. Among 21 patients where initial lumpectomy histopathology margin was free of cancer, residual malignancy was found in 57% of patients. Prior excision of lumps for breast cancer does not affect the accuracy of SLNB. Peri-areoral scar may be associated with high FNR and low IR, although further studies are needed to validate this statement. Definitive breast surgery is required for all patients, irrespective of initial lumpectomy histopathological margin status.