Lower expression of MMP2, FLNA, and CFL1 is correlated with favorable prognosis in invasive micropapillary breast cancer

Purpose: Despite its recognized aggressive clinical manifestations, invasive micropapillary carcinoma has a controversial prognosis in comparison to invasive ductal carcinoma of the breast. This retrospective study aimed to explore the prognosis and underlying molecular mechanisms of invasive micropapillary carcinoma.

Methods: Through the SEER database, we compared patients survival outcomes with invasive micropapillary carcinoma versus invasive ductal carcinoma, and developed a nomogram to predict the overall survival of the former group. We explored gene profiles of invasive micropapillary carcinoma in the GEO database. Hub genes were identified as the top ten genes in the PPI network with the highest degrees of connectivity, and three of them were selected for validation by immunohistochemistry.

Results: Invasive micropapillary carcinoma patients had better overall survival and breast cancer-specific survival than invasive ductal carcinoma patients did. Multivariate analysis revealed age, marital status, TN stage, ER status, and chemotherapy as independent prognostic factors for invasive micropapillary carcinoma patients, which were used to construct a nomogram with good performance. A total of 294 DEGs were identified, with ten hub genes, including MMP2, FLNA and CFL1, which were expressed at lower levels in invasive micropapillary carcinoma patients than in invasive ductal carcinoma patients, indicating favorable outcomes.

Conclusions: Patients with invasive micropapillary carcinoma generally have a better prognosis than those with invasive ductal carcinoma does, which could be attributed to the lower expression of pro-oncogenic genes in the former group; however, the underlying mechanism needs further investigation.