Objective:To analyze risk factors of breast ductal carcinoma in situ (DCIS) with microinvasion (DCIS-MI) and explore suitable axillary lymph node surgery treatment for patients with DCIS-MI. Methods:The clinical characteristics, such as age, menopausal status at diagnosis, size of breast mass, and pathology reports of 45 patients with breast DCIS or DCIS-MI treated at Jinling Hospital, Medical School of Nanjing University from February 2013 to February 2016, were retrospectively collected and analyzed statistically to deter-mine the risk factors associated with microinvasion. Results:Premenopause (P=0.006), tumor size≥3.15 cm (P=0.006), and family his-tory of malignant tumor (P=0.002) were proven risk factors of DCIS-MI. Conclusion:Patients with clinical palpable axillary mass, pre-menopause, large breast mass, and family history of malignant tumor demonstrated high possibility of DCIS-MI. Hence, sentinel lymph node biopsy should be performed. Axillary lymph node dissection is highly recommended to patients whose main symptom is palpable axillary mass.