Ductal carcinoma in situ and sentinel lymph node biopsy

Purpose: Axillary lymph node status is the strongest prognostic indicator of survival for women with breast cancer. The purpose of this study was to evaluate whether sentinel lymph node biopsy (SLNB) is required in patients with an initial diagnosis of ductal carcinoma in situ (DCIS).

Methods: A retrospective analysis was performed of 78 patients with an initial diagnosis of DCIS between December 2002 and April 2010 and who proceeded to have either SLNB or axillary node dissection performed as part of their primary surgical procedure. The study focused on the rates of axillary node metastasis and the underestimation of invasive carcinoma at an initial diagnosis.

Results: Forty-eight patients underwent SLNB and 18 patients underwent axillary node dissection. Only 1 of 66 patients (1.5%) had a positive sentinel lymph node. After definite surgery, the final diagnosis was changed to invasive ductal carcinoma (IDC) in 12 patients and DCIS with microinvasion in 2 patients; 14 of 78 patients (17.9%) were therefore underestimated at preoperative histological examinations. In 35 patients who were diagnosed DCIS by core needle biopsy (CNB), 13 patients (37.1%) were upstaged into IDC or DCIS with microinvasion in the final diagnosis. The statistically significant factors predictive of invasive breast cancer were a large tumor size and HER2 overexpression.

Conclusion: The rates of SLNB positivity in pure DCIS are very low, and there is continuing uncertainty about its clinical importance. However in view of the high rate of underestimation of invasive carcinoma in patients with an initial diagnosis of DCIS, SLNB appears to be appropriate in these patients, especially in the case when DCIS is diagnosed by a core needle biopsy. In patients with an initial diagnosis of DCIS by CNB, SLNB should be considered as part of the primary surgical procedure, when preoperative variables show a tumor larger than 2.35 cm and with HER2 overexpression.