Clinicopathological characteristics, treatments, and prognosis of breast ductal carcinoma in situ with microinvasion: A narrative review

BACKGROUND: Ductal carcinoma in situ with microinvasion (DCIS‐MI) is defined as ductal carcinoma in situ (DCIS) with a microscopic invasive focus ≤1 mm in the longest diameter. The current literature is controversial concerning the clinical prognostic features and management of DCIS‐MI. This narrative review described recently reported literature regarding the characteristics, treatment, and prognosis of it. METHODS: Searching PubMed for relevant articles covering the period of 1982 to 2021 using the following terms by MeSH and free‐word: breast cancer, microinvasion, DCIS, DCIS‐MI, and invasive ductal carcinoma (IDC). RESULTS: DCIS‐MI tends to express more aggressive pathological features such as necrosis, HER2+, ER‐ or PR‐, and high nuclear grade. The overall prognosis of DCIS‐MI is typically good, however, some indicators such as young age, HR‐, HER2+ and multimicroinvasive lesions, were associated with worse prognoses. And there are also conflicting results on the differences between the prognoses of DCIS‐MI and DCIS or T1a‐IDC. Postoperative chemotherapy and anti‐HER2 therapy still have uncertain benefits and are more likely to be used to treat high‐risk patients who are HR‐ orHER2+ to improve the prognosis. CONCLUSION: DCIS‐MI has more aggressive pathological features, which may suggest its biological behavior is worse than that of DCIS and similar to early IDC. Although the overall prognosis of DCIS‐MI is good, when making decisions about adjuvant therapy clinicians need to give priority to the hormone receptor status, HER2 expression and axillary lymph node status of patients, because these may affect the prognosis and treatment response.