A risk score based on histopathological features predicts higher risk of distant recurrence in premenopausal patients with lymph node-negative endocrine-responsive breast cancer

Purpose: To develop a Risk Score (RS) to predict distant recurrence among premenopausal women with node-negative endocrine-responsive early breast cancer. Methods: The Cox model was used to develop the RS using clinical and histopathological features from 378 women participating in the IBCSG Trial VIII who received endocrine therapy alone or following chemotherapy. The performance of the resulting model was validated on a cohort of 1005 patients from a single institution who received endocrine therapy alone. Results: In a multivariable analysis, the risk of distant recurrence was associated with tumor size, ER, Ki-67 and peritumoral vascular invasion. In the validation cohort, patients with high RS were at greater risk of distant recurrence compared to patients with low RS (HR, 17.41; 95% CI, 5.72-52.95). Conclusion: In premenopausal women with node-negative endocrine-responsive early breast cancer, the RS identifies patients at higher risk of distant recurrence.