Analysis of prognostic factors and construction of prognostic models for breast invasive lobular carcinoma

Purpose: Invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) account for most breast cancers. However, there is ongoing controversy regarding the differences in overall survival (OS) between ILC and IDC. The aim of this study was to compare survival between IDC and ILC, identify prognostic factors for ILC patients and to construct a nomogram for predicting the OS rates. Methods: As a retrospective cohort analysis, this study utilized data from the Surveillance, Epidemiology and End Results (SEER) Cancer Database. Patients diagnosed with ILC and IDC between 2000 and 2019 were chosen. To minimize baseline differences in clinicopathological characteristics and survival outcomes, we used a propensity score matching (PSM) method. The data from the multivariate Cox regression analyses were used to construct apredictive nomogram for OS at 1, 3 and 5 years, incorporating all independent prognostic factors. Results: Following the PSM procedure, patients with ILC exhibited a better prognosis compared to those with IDC. TNM stage, age>70, radiotherapy, surgery, estrogen receptor (ER), progesterone receptor (PR)and HR-/HER2+ subtype were independent factors for OS in ILC patients. Surgery and radiotherapy were found in this study to effectively reduce the risk of death while chemotherapy did not demonstrate the same benefit . Conclusions: The nomogram displayed strong predictive performance and can support clinicians to evaluate the prognosis of ILC in decision-making and patient counseling.