Clinicopathologic Characteristics and Prognosis of Invasive Papillary Carcinoma of the Breast

Background Invasive papillary carcinoma (IPC) of the breast is thought to carry a more favorable prognosis than invasive ductal carcinoma (IDC). The aim of this study is to investigate the clinicopathological characteristics between IPC and IDC and their prognosis using a large nationwide data set. Methods Female patients diagnosed with malignant IPC and IDC between 2005 and 2014 were analyzed. Patients with incomplete survival data, stage 0/IV, unknown stage, or recurrent disease were excluded. Five-year overall survival was compared between IPC and IDC. Results Among 308,426 patients, 1147 had IPC and 307,279 had IDC. IPC presented more in older postmenopausal women, black Americans, and people who had government insurance. IPC had larger tumor size, lower-grade, and earlier-stage disease, less node-positive disease, higher hormone positivity, and lower human epidermal growth factor receptor 2 amplification. Adjuvant radiation and chemotherapy rates were lower in IPC than those in IDC. IPC had a similar 5-year overall survival as compared with IDC overall (86.8% versus 88.7%) (P = 0.06). Age, pathologic stage, and radiation treatment were shown to be independent prognostic factors of IPC. Conclusions IPC has a similar prognosis as IDC, suggesting that these patients should follow the same treatment protocols.