Background Ductal carcinoma in situ with microinvasion (DCISM), defined as invasion ≤ 1 mm, occurs in 5%–10% of DCIS cases. There is ongoing debate on whether DCISM should be managed as DCIS or as small invasive cancer. As treatments increasingly emphasize minimizing morbidity, efforts have focused on identifying low‐risk patients who may safely forgo axillary surgery, including sentinel lymph node biopsy (SLNB). However, axillary management of DCISM remains unclear due to limited data. This study aims to identify preoperative predictors of upstaging to invasive carcinoma on final pathology to guide SLNB use. Methods A retrospective chart review was conducted of women aged ≥ 19 years with confirmed or suspected DCISM on initial biopsy who were clinically node negative and treated at a tertiary center from 2013 to 2023. Fisher’s exact test and Student′s t ‐test were used for categorical and continuous variables, respectively. Univariate and multivariate analyses were performed to identify predictors of upstaging. Results A total of 61 women with DCISM on initial biopsy were identified. Of these, 40.9% (25/61) were upstaged to invasive carcinoma on final pathology. Among upstaged patients, 95% (19/20) underwent SLNB at the time of surgery, and 12.5% (3/24) had positive lymph nodes. Time from biopsy to surgery did not differ significantly between groups ( p = 0.12). Preoperative predictors of upstaging included palpable mass (OR 9.0, 95% CI 2.38–44.98, p = 0.003), mass on mammogram (OR 12.86, 95% CI 1.95–255.34, p = 0.02), and mass with calcifications (OR 13.34, 95% CI 1.30–255.08, p = 0.047). Conclusion Clinically node‐negative DCISM patients without a palpable or mammographic mass (with or without calcifications) had a low risk of upstaging and lymph node involvement, suggesting that they may safely forgo SLNB. Identifying preoperative variables can guide risk stratifications and de‐escalation of axillary surgery. Larger prospective studies are needed to further inform guidelines for DCISM management in diverse populations.
Huang et al. (Thu,) studied this question.