Sentinel lymph node biopsy in clinically detected ductal carcinoma in situ.

Aim: To study the indications for sentinel lymph node biopsy (SLNB) in clinically-detected ductal carcinoma in situ (CD-DCIS).

Methods: A retrospective analysis of 20 patients with an initial diagnosis of pure DCIS by an image-guided core needle biopsy (CNB) between June 2006 and June 2012 was conducted at King Faisal Specialist Hospital. The accuracy of performing SLNB in CD-DCIS, the rate of sentinel and non-sentinel nodal metastasis, and the histologic underestimation rate of invasive cancer at initial diagnosis were analyzed. The inclusion criteria were a preoperative diagnosis of pure DCIS with no evidence of invasion. We excluded any patient with evidence of microinvasion or invasion. There were two cases of mammographically detected DCIS and 18 cases of CD-DCIS. All our patients were diagnosed by an image-guided CNB except two patients who were diagnosed by fine needle aspiration (FNA). All patients underwent breast surgery, SLNB, and axillary lymph node dissection (ALND) if the SLN was positive.

Results: Twenty patients with an initial diagnosis of pure DCIS underwent SLNB, 2 of whom had an ALND. The mean age of the patients was 49.7 years (range, 35-70). Twelve patients (60%) were premenopausal and 8 (40%) were postmenopausal. CNB was the diagnostic procedure for 18 patients, and 2 who were diagnosed by FNA were excluded from the calculation of the underestimation rate. Two out of 20 had a positive SLNB and underwent an ALND and neither had additional non sentinel lymph node metastasis. Both the sentinel visualization rate and the intraoperative sentinel identification rate were 100%. The false negative rate was 0%. Only 2 patients had a positive SLNB (10%) and neither had additional metastasis following an ALND. After definitive surgery, 3 patients were upstaged to invasive ductal carcinoma (3/18 = 16.6%) and 3 other patients were upstaged to DCIS with microinvasion (3/18 = 16.6%). Therefore the histologic underestimation rate of invasive disease was 33%.

Conclusion: SLNB in CD-DCIS is technically feasible and highly accurate. We recommend limiting SLNB to patients undergoing a mastectomy.