IntroductionCurrent guidelines recommend that sentinel lymph node biopsy (SLNB) be performed in patients with ductal carcinoma in situ (DCIS) undergoing mastectomy, in patients for whom the location of excision may compromise future SLNB, or if there is a high suspicion or risk of upstaging to invasive cancer on final pathology. Whether axillary surgery should be performed in patients with DCIS remains controversial. Our study aimed to examine the factors associated with the upgrade of DCIS to invasive cancer on final pathology and sentinel lymph node (SLN) metastases to evaluate whether axillary surgery may be safely omitted in DCIS.MethodsPatients with a diagnosis of DCIS on core biopsy who underwent surgery with axillary staging between 2016 and 2022 were identified from our pathology database and retrospectively reviewed. Patients who underwent surgical management of DCIS without axillary staging and those treated for local recurrence were excluded.ResultsOut of 65 patients, 35.3% of patients were upstaged to the invasive disease on final pathology. 9.23% of cases had a positive SLNB. Predictive factors associated with upstaging to invasive cancer included palpable mass on clinical examination (P = 0.013), presence of a mass on preoperative imaging (P = 0.040), and estrogen receptor status (P = 0.036).ConclusionOur results support ongoing opportunities for the de-escalation of axillary surgery in patients with DCIS. In a subset of patients undergoing surgery for DCIS, SLNB may be omitted as the risk of upstaging to invasive cancer is low. Patients with a mass on clinical examination or imaging and negative estrogen receptor (ER) lesions have a higher risk of upstaging to invasive cancer, where a sentinel lymph node biopsy should be performed.