Background: The implementation of sentinel lymph node biopsy (SLNB) when ductal carcinoma in situ (DCIS) diagnosed from core needle biopsy (CNBx) is controversial.

Objective: To investigate the value of SLNB in patients with a preoperative diagnosis of DCIS focusing on the requirement of reoperation and determine the factors associated with upstaging to invasive carcinoma.

Materials and Methods: Data of all patients with a preoperative CNBx-diagnosed of DCIS who underwent SLNB at the time of definitive surgery at the Division of Head-Neck and Breast Surgery, Department of Surgery, Siriraj Hospital, Mahidol University, Thailand from January 2001 to December 2011 were collected. The outcomes were then analyzed regarding clinical, radiographic and pathologic data in relation to histological upstaging and SLNB results.

Results: One hundred and seventy-five patients with a CNBx-diagnosed of DCIS underwent 178 SLNB at the time of definitive
surgery while one hundred and ten patients (61.8%) were detected by screening mammogram without abnormal clinical findings. In addition, SLNB was successful in 168 patients (94.4%) and 10 patients (5.6%) had SLN metastases and sixty-eight patients (38.2%) had histological upstaging based on an invasive component identified on the final specimen and SLN was positive in 9 cases (13.2 %). Among 110 patients, there is 1 SLN metastasis (0.9%) found on a patient who had “pure DCIS” on final pathology. The independent predictors for existence of invasive components were presence of a palpable tumor (OR 4.105, 95% CI 1.745 to 9.656, p = 0.001), initial high nuclear grade DCIS (OR 2.370, 95% CI 1.156 to 4.860, p = 0.019) and focal microinvasion (OR 2.370, 95% CI 1.163 to 12.620, p = 0.027).

Conclusion: More than one-third of patients with diagnosis of DCIS by CNBx had invasive components in final pathology. Hence, SLNB should be performed during definitive surgery to avoid second operation especially in those who have high risk for harboring invasive cancer.

Keywords: Breast cancer, Ductal carcinoma in situ, Sentinel lymph node biopsy