Sociodemographic and clinicopathologic features associated with rapid relapse in triple-negative breast cancer: a Swedish nationwide registry-based study

Abstract Purpose To characterize clinicopathologic, treatment-related, and sociodemographic factors associated with rapid versus late relapse in triple-negative breast cancer (TNBC), and to evaluate how relapse timing influences metastatic patterns and survival outcomes. Methods Using linked Swedish population-based registers, we conducted a retrospective cohort study of women diagnosed with non-metastatic TNBC between 2007 and 2021. Patients were classified into three groups based on time to distant relapse or death: rapid relapse (rrTNBC; ≤24 months), late relapse (lrTNBC; >24 months), or event-free at last follow-up. Tumor characteristics, comorbidity, treatments, and sociodemographic variables were compared across groups. Multivariable logistic regression and survival outcomes were assessed. Sensitivity analyses restricted to healthcare regions with complete relapse data were performed. Results Among 8,298 patients, 15% experienced rrTNBC, 18% lrTNBC, and 67% remained event-free. rrTNBC was associated with older age, larger tumors, nodal involvement, advanced stage, and a higher frequency of visceral and multi-organ metastases. Patients with rrTNBC were less likely to receive adjuvant systemic therapy or radiotherapy and more likely to undergo mastectomy. Sociodemographic disparities were observed, with rrTNBC more frequent among patients who were single or widowed, lower educated, or had lower household income. Survival outcomes were substantially worse for rrTNBC compared with lrTNBC and event-free patients. Conclusions Rapid relapse defines a particularly vulnerable TNBC population characterized by aggressive tumor biology, early dissemination, inferior survival, and sociodemographic disadvantage, while lrTNBC represents an intermediate phenotype with delayed disease progression. Distinguishing rrTNBC from lrTNBC may improve risk stratification, guide treatment decisions, and support more personalized follow-up strategies.