CanAssist Breast Provides Additional Insightful Prognostic Information in Retrospective, Pooled Secondary Analysis in Clinically Low/ High-Risk Patients With HR+/HER2- EBC

Background: In patients with early-stage HR+/ HER2- breast cancer, younger age, node positivity (N+), and higher Ki67 index are considered ``clinically high-risk'' and are treated with chemotherapy, although some can do well without it. Chemotherapy is often avoided in ``clinically low-risk'' patients with older age, small (T1-T2) or node-negative (N0) or lower Ki67 tumors; however, some of these patients do recur. Unlike earlier studies, this study aimed to explore the potential of CanAssist Breast (CAB), a prognostic test in providing ``additional'' information beyond ``clinicopathological parameters'' in ``clinically'' low-risk/ high-risk patients for effective treatment management. Methods: This is a secondary pooled data analysis of previously published retrospective studies wherein CAB risk stratification data of 3045 patients were used to assess the risk of recurrence at five years from diagnosis. Distant recurrence-free interval (DRFI) was evaluated from Kaplan–Meier curves. Results: In patients having N0 disease, CAB identified 13% and 8% high-risk patients with small tumors and small tumors with low Ki67 levels, respectively. In patients with N+ disease, CAB identified 44% of patients with higher Ki67 (≥20%) as low-risk. In younger patients, CAB identified >46% of patients as low-risk. In low ER-expressing patients, CAB identified 67% of patients as low-risk. All CAB low-risk patients have an acceptable DRFI of ≥ 89% at five years from diagnosis. Conclusions: CAB provides additional prognostic information by identifying ``low-risk'' and ``high-risk'' patients from the ``clinically'' high-risk and low-risk groups, thereby guiding oncologists to either avoid aggressive therapies or govern significant treatment decisions on additional therapies.