Invasive micropapillary carcinoma of the breast had no difference in prognosis compared with invasive ductal carcinoma: a propensity-matched analysis

Abstract

Invasive micropapillary carcinoma (IMPC) is a rare histopathological variant of breast carcinoma that is usually associated with poor clinical characteristics. Whether IMPC has worse prognosis than invasive ductal carcinoma (IDC) is controversial. This retrospective study examined the prognostic difference between IMPC and IDC. We analysed 327 cases of IMPC patients and 4979 IDC cases who underwent primary resection in our institution between 2008 and 2012. Using propensity score matching, the two groups were matched at 1:1 by age, tumour size, nodal status, hormone status, and HER2 status. Differences in prognosis were assessed by Kaplan-Meier estimates and Cox regression analysis. We established the IMPC group and identified 324 IDC patients by propensity score matching. The survival analysis indicated that IMPC patients had no significant reduced overall survival (p = 0.752) or disease-free survival (p = 0.578) compared with IDC patients. Multivariate Cox regression analysis revealed that IMPC was not an independent prognostic factor for disease-free survival (hazard ratio [HR] = 0.944; 95% confidential interval [CI], 0.601–1.481) or overall survival (HR = 0.727; 95% CI, 0.358–1.478). Survival analysis demonstrated no statistically significant difference between IMPC and IDC, indicating that proactive or radical clinical therapy is unnecessary.