Selective omission of sentinel lymph node biopsy in mastectomy for ductal carcinoma in situ: Identifying eligible candidates

Background: Sentinel lymph node biopsy (SLNB) is recommended for patients with ductal carcinoma in situ (DCIS) undergoing mastectomy, given the concerns regarding upstaging and technical difficulties of postmastectomy SLNB. However, this may lead to potential overtreatment, considering favorable prognosis and deescalation trends in DCIS. Data regarding upstaging and axillary lymph node metastasis among these patients remain limited. Methods: We retrospectively reviewed patients with DCIS who underwent mastectomy with SLNB or axillary lymph node dissection at Gangnam Severance Hospital between January 2010 and December 2021. To explore the feasibility of omitting SLNB, we assessed upgrade rates to invasive carcinoma and axillary lymph node metastasis. Binary Cox regression analysis was performed to identify clinicopathologic factors associated with upstaging and axillary lymph node metastasis. Results: Among 385 patients, 164 (42.6%) experienced an invasive carcinoma upgrade: microinvasion, pT1, and pT2 were confirmed in 53 (13.8%), 97 (25.2%), and 14 (3.6%) patients, respectively. Seventeen (4.4%) patients had axillary lymph node metastasis. Multivariable analysis identified age ≤50 years (odds ratio [OR], 4.81; 95% confidence interval [CI], 1.31–17.62; p = 0.018) and suspicious axillary lymph nodes on radiologic evaluation (OR, 10.67; 95% CI, 3.58–31.81; p 50 years with no suspicious axillary lymph nodes, only two (1.7%) experienced axillary lymph node metastasis. Conclusions: Although underestimation of the invasive component was relatively high among patients with DCIS undergoing mastectomy, axillary lymph node metastasis was rare. Our findings suggest that omitting SLNB may be feasible for patients over 50 without suspicious axillary lymph nodes on radiologic evaluation.