Distant metastasis and prognostic factors in patients with invasive ductal carcinoma of the breast.

OBJECTIVE: To explore the risk factors and prognostic factors of invasive ductal carcinoma (IDC) and to predict the survival of IDC patients with metastasis. METHOD: We used multivariate logistic regression to identify independent risk factors affecting metastasis in IDC patients and used Cox regression to identify independent prognostic factors affecting the overall survival of patients with metastasis. Nomogram was used to predict survival, while C-index and calibration curves were used to measure the performance of nomogram. Kaplan-Meier method was used to calculate the survival curves of patients with different independent prognostics factors and different metastatic sites, and the differences were compared by log-rank test. The data of our study were obtained from the Surveillance, Epidemiology and End Results cancer registry. RESULT: Our study included 226,094 patients with IDC. In multivariate analysis, independent risk factors of metastasis included age, race, marital status, income, geographic region, grade, T stage, N stage, subtype, surgery and radiotherapy. Independent prognostic factors included age, race, marital status, income, geographic region, grade, T stage, N stage, subtype, surgery and chemotherapy. We established a nomogram, of which the C-index was 0.701 (0.693, 0.709), with the calibration curves showing that the disease-specific survival between actual observation and prediction had a good consistency. The survival curves of different metastatic patterns were significantly different (log-rank test: χ2  = 18784, p < 0.001; χ2  = 47.1, p < 0.001; χ2  = 20, p < 0.001). CONCLUSION: The nomogram we established may provide risk assessment and survival prediction for IDC patients with metastasis, which can be used for clinical decision-making and reference.