Background: There is uncertainty about the utility of sentinel node biopsy (SNB) for ductal carcinoma in situ (DCIS) and its potential to avoid axillary lymph node dissection (ALND) in patients undergoing mastectomy for DCIS.
Methods: A review was conducted of 179 patients who underwent mastectomy with sentinel node biopsy for DCIS without invasion or microinvasion on premastectomy pathology review.
Results: The sentinel node identification rate was 98.9% (177/179). Twenty (11.3%) of 177 mastectomies for DCIS had a positive SNB: two micrometastasis (pN1mi) and 18 isolated tumor cells [pN0(i+)]. Unsuspected invasive cancer was found in 20 (11.2%) of 179 mastectomies, eight T1mic, five T1a, three T1b, and four T1c tumors. Sentinel nodes were identified in 19 of 20 patients with invasive cancer and four were positive: one pN1mi and three pN0(i+). Eighteen of 19 patients with unsuspected invasive cancer were able to avoid axillary dissection on the basis of SNB results. Of the 159 patients whose final pathology revealed DCIS without invasion, a sentinel node was identified in 158 (99.4%). The SNB was positive in 16 patients (10.1%): one pN1mi and 15 pN0(i+). Three patients underwent ALND on the basis of positive SNBs and in each the SNB was the only positive node.
Conclusions: 11% of patients undergoing mastectomy for DCIS were found to have invasive cancer on final pathology. The use of SNB during mastectomy for DCIS allowed nearly all such patients to avoid axillary dissection. These results support routine use of SNB during mastectomy for DCIS.