MKI67 and neoplasm: The ELIOT trial concluded that IORT should be offered to selected patients with a low risk of local recurrence, specifically those with a well-differentiated tumor ≤ 1 cm, Ki67 < 14%, and classified as luminal A. In that study, only 5% of ELIOT IORT patients (those with C4-positive nodes) got additional WBRT [25].