Nomogram for predicting distant metastasis and prognosis in HR+/HER2- breast cancer patients without lymph node metastasis

Background: HR+/HER2- breast cancer patients without lymph node metastasis (N0) but with distant metastasis (DM) are rare. This study aims to explore the risk factors of N0 patients with distant metastasis and build nomogram to predict the occurrence and prognosis of distant metastasis. Methods Patients with HR+/HER2- N0 breast cancer diagnosed between 2010 and 2017 were retrospectively collected from the Surveillance, Epidemiology, and End Result (SEER) database. Univariate and multivariate logistic analysis were performed to identify risk factors for DM. Nomogram was constructed based on multivariate regression results. Univariate and multivariate Cox regression were used to identify the prognostic factors of DM patients, and Nomogram was constructed to predict 1-year, 3-year, and 5-year BCSS. The performance of nomogram was evaluated by concordance index (C-index), receiver operating characteristic (ROC) curves, calibration curve and decision curve analyses (DCAs). Results A total of 63005 patients were enrolled, including 1208 patients (1.3%) with DM. Race, T stage, location, grade and PR were independent risk factors for DM. The area under curve (AUC) values of the development cohort and validation cohort were 0.835 and 0.836, respectively. Seven significant prognostic factors including age, race, grade, ER, PR, surgery, and site of metastasis were included to build nomogram to predict 1-year, 3-year, and 5-year BCSS. The C-index of the development cohort and validation cohort were 0.70 and 0.68, respectively. Conclusions Our nomogram can predict the occurrence and prognosis of DM in HR+/HER2- N0 patients, providing guidance for individualized survival assessment and appropriate treatment for the special population.