Survival and Trends in Annualized Hazard Function by Age at Diagnosis Among Chinese Breast Cancer Patients Aged ≤40 Years: Case Analysis Study (Preprint)

Abstract

BACKGROUND Young breast cancer patients are more likely to develop aggressive tumor characteristics and worse prognosis than older women, and have distinct epidemiology and prognosis in different races. However, rare studies have evaluated the clinical biological features and relapse patterns according to different age strata of young women in Asia OBJECTIVE To explore the survival difference and hazard function of young breast cancer (BC) by age in Chinese patients. METHODS The patients were enrolled from West China hospital, Sichuan University. Chi-squared test, Kaplane-Meier analysis, log-rank test, cox multivariate hazards regression model, and hazard function were applied for data analyzing. RESULTS We included 1,950 young BC patients diagnosed between 2008 and 2019. Patients aged ≤ 25, 26-30, 31-35, and 36-40 years accounted for 2.8%, 11.7%, 27.6%, and 57.8%, respectively. The diagnosis of young BC significantly increased from 2008 to 2019. Five-year locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), breast cancer-specific survival (BCSS), and overall survival (OS) for the entire population were 98.3%, 93.4%, 94.3%, and 93.9%, respectively. Patients aged ≤25 years had significantly poorer 5-year LRFS (P<.001), 5-year DMFS (P<.001), 5-year BCSS (P=.04), and 5-year OS (P=.04) than those aged 31-35, 26-30, and 36-40 years. The annualized hazard function for recurrence, metastasis, and BC mortality in all patients and different age strata showed significantly different trends, especially for BC mortality. CONCLUSIONS The annual diagnosis of young BC seemed to increase in Chinese patients, and distinct age-strata of young BC patients didn’t differ for survival outcome and failure patterns.