Key clinical point: Simultaneous integrated boost (SIB) radiotherapy was safe and demonstrated noninferior clinical outcomes compared with sequential photon tumor-bed boost in patients with early breast cancer (BC) who underwent breast-conserving surgery (BCS).
Major finding: SIB with 48 Gy in 15 fractions to the tumor-bed volume vs sequential photon tumor-bed boost resulted in comparable rates of ipsilateral breast tumor relapse (hazard ratio [HR] 1.04; P = .91), whereas dose-escalated SIB (53 Gy) proved disadvantageous (HR 1.76; P = .041). There was no increase in toxicity outcomes with 48 Gy SIB vs sequential photon tumor-bed boost.
Study details: Findings are from the phase 3 IMPORT HIGH study including 2617 patients with early BC who underwent BCS and were randomly assigned to receive sequential photon tumor-bed boost or SIB with 48 or 53 Gy in 15 fractions to the tumor-bed volume.
Disclosures: This study was supported by Cancer Research U.K. Some authors declared receiving grants or funding from various sources, including Cancer Research U.K.
Source: Coles CE et al. Dose-escalated simultaneous integrated boost radiotherapy in early breast cancer (IMPORT HIGH): A multicentre, phase 3, non-inferiority, open-label, randomised controlled trial. Lancet. 2023 (Jun 8). doi: 10.1016/S0140-6736(23)00619-0