Risk Factors and Prognosis Analysis of Infiltrating Micropapillary Carcinoma of Breast: A Retrospective Study

Invasive micropapillary carcinoma (IMPC) is a rare breast cancer subtype with high invasiveness and lymphovascular/lymph node metastasis. While poor prognosis is reported, long-term survival and roles of molecular subtyping/laboratory markers remain unclear.

We retrospectively analyzed 653 IMPC patients from a Chinese center (as of December 2024). Kaplan-Meier estimated progression-free survival (PFS) and overall survival (OS); Cox regression assessed prognostic factors.

Among 653 patients with IMPC, the molecular subtype distribution was as follows: HR+/HER2-, 48.2%; HR+/HER2+, 35.4%; HR-/HER2-, 11.0%; and HR-/HER2+, 5.4%. Most patients had T1-2 disease and were postmenopausal. The 3-year and 5-year OS rates were 97.42% and 93.73%, respectively, while the 3-year and 5-year PFS rates were 90.66% and 81.20%, respectively. Kaplan-Meier analysis showed significant differences in PFS among molecular subtypes, but not in OS. In multivariable analysis, the HR+/HER2+ subtype and higher total bilirubin were independently associated with better PFS, whereas higher systemic immune-inflammation index and stage IIIB were associated with worse PFS. Poorer OS was independently associated with advanced stage, no surgery, alcohol consumption history, higher systemic immune-inflammation index, menopausal status, and elevated blood glucose, while mastectomy and endocrine therapy were associated with better OS.

IMPC shows favorable OS but requires progression risk monitoring. PFS varied by molecular subtype, while OS did not. Molecular typing, clinical stage, and inflammatory/biochemical markers aid prognosis and personalized treatment.