Real-world correlation of invasive disease-free survival and overall survival in HR+/HER2- early breast cancer

Overall survival (OS) is the gold standard for assessing clinical benefit in oncology but requires extended follow-up to detect sufficient events. A retrospective analysis of the ConcertAI Patient360 database from January 1995 to April 2021 assessed invasive disease-free survival (IDFS) as a real-world surrogate endpoint for OS in adjuvant HR-positive/HER2-negative early breast cancer (HR+/HER2- EBC). A total of 3133 patients were included (mean age 58.4 years, 98.8 were female, 29.9% were premenopausal, and 80.9% had stage II disease. During median 55.1 months follow-up 1103 (35.2%) IDFS events and 554 (17.7%) OS events occurred. IDFS and OS exhibited a positive, strong, and clinically relevant correlation (Spearman ρ: 0.88; iterative multiple imputation ρ: 0.83; both p<0.001). IDFS accounted for 82% of variation in OS (R²=0.82). Results of all subgroup analyses were consistent with overall population. The authors conclude that this patient-level analysis demonstrated very strong, positive correlations between IDFS and OS in adjuvant HR+/HER- EBC.