| Abstract: |
Background: Overall survival (OS) is the gold standard for assessing clinical benefit in oncology but requires extended follow-up to detect sufficient events. Invasive disease-free survival (iDFS) requires shorter follow-up times and is considered an objective and clinically meaningful end point in early breast cancer (EBC) trials. The authors assessed iDFS as a surrogate end point for OS in adjuvant HR+/HER2– EBC using real-world patient-level data. Methods: A retrospective analysis was conducted on patient data from the ConcertAI Patient360 database (January 1995–April 2021). Key inclusion criteria: age ≥18 years, stage II or III (AJCC 8th Edition) HR+/HER2– EBC, prior surgery, adjuvant endocrine therapy (ET). Spearman ρ, iterative multiple imputation ρ (IMI; 0.8–1 considered “very strong”), and R2 (clinical relevance R2 ≥ 0.70) were used to assess iDFS–OS relationship. Subgroup analyses included ET (nonsteroidal aromatase inhibitor or tamoxifen), stage, menopausal status, nodal status, prior (neo)adjuvant chemotherapy, and prior radiotherapy. Results: A total of 3133 patients were included (1103 [35.2%] iDFS events; 554 [17.7%] OS events); mean age was 58.4 years, 98.8% were female, 29.9% were premenopausal, and 80.9% had stage II disease. Median follow-up time was 55.1 months. iDFS and OS exhibited a positive, very strong, clinically relevant correlation (Spearman ρ: 0.88 [0.87–0.89]; IMI ρ: 0.83 [0.79–0.86]; both p <.0001). iDFS accounted for 82% of variation in OS (R2 = 0.82). Results of all subgroup analyses were consistent with overall population. Conclusions: This patient-level real-world analysis demonstrated very strong, positive correlations between iDFS and OS, supporting the use of iDFS as a reliable primary end point in adjuvant HR+/HER2– EBC. © 2025 The Author(s). Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society. |
| Keywords: |
adult; cancer survival; aged; disease-free survival; middle aged; retrospective studies; major clinical study; overall survival; mortality; cancer recurrence; adjuvant therapy; cancer radiotherapy; disease free survival; chemotherapy, adjuvant; cancer staging; follow up; metabolism; epidermal growth factor receptor 2; aromatase inhibitor; cohort analysis; pathology; breast neoplasms; retrospective study; correlation analysis; adjuvant chemotherapy; breast tumor; tamoxifen; receptor, erbb-2; receptors, estrogen; receptors, progesterone; hormonal therapy; letrozole; neoadjuvant chemotherapy; premenopause; estrogen receptor; progesterone receptor; anastrozole; menopause; aromatase inhibitors; therapy; erbb2 protein, human; clinical outcome; cancer prognosis; humans; human; female; article; hormone receptor-positive, her2-negative breast cancer; real world; hr+/her2– early breast cancer; invasive disease-free survival; invasive disease free survival
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