Challenges for breast radiotherapy with SIB: the IMPORT HIGH trial
Authors: Fabiana Gregucci, Antonella Ciabattoni
Journal: The Lancet (2024)

Charlotte E Coles and colleagues,1Coles CE Haviland JS Kirby AM 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; 401: 2124-2137Summary Full Text Full Text PDF PubMed Google Scholar on behalf of the IMPORT Trial Management Group, published the results of a phase 3, non-inferiority trial (IMPORT HIGH) comparing standard breast radiotherapy with a sequential (23 fractions) or concomitant (simultaneous integrated boost of 15 fractions) boost to the tumour bed. The trial randomly assigned 2617 patients with early breast cancer and showed comparable safety and efficacy (defined as incidence of ipsilateral breast recurrence) of the shorter regimens at a median follow-up of 74 months. From a patient perspective, the concomitant boost regimen meant 15 visits to the radiation oncology centre instead of 23 visits. A concurrent boost for breast cancer adjuvant radiotherapy was originally pilot-tested at New York University, USA;2Formenti SC Gidea-Addeo D Goldberg JD et al.Phase I–II trial of prone accelerated intensity modulated radiation therapy to the breast to optimally spare normal tissue.J Clin Oncol. 2007; 25: 2236-2242Crossref PubMed Scopus (156) Google Scholar 91 patients were treated in a prospective trial with a setup on a prone position to best spare the heart and lungs. In 2014, the same group reported a 5-year cumulative in-breast recurrence rate of 0·82% among 404 consecutive trial patients: the final cosmetic result was judged as excellent or good by 82% of patients.3Osa EO DeWyngaert K Roses D et al.Prone breast intensity modulated radiation therapy: 5-year results.Int J Radiat Oncol Biol Phys. 2014; 89: 899-906Summary Full Text Full Text PDF PubMed Google Scholar In patients with irradiated left side for breast cancer, the mean cardiac dose was 1·03 Gy (95% CI 0·87–1·19),4Brenner DJ Shuryak I Jozsef G DeWyngaert KJ Formenti SC Risk and risk reduction of major coronary events associated with contemporary breast radiotherapy.JAMA Intern Med. 2014; 174: 158-160Crossref PubMed Scopus (38) Google Scholar which drastically reduced the risk of late cardiovascular sequelae of radiotherapy.4Brenner DJ Shuryak I Jozsef G DeWyngaert KJ Formenti SC Risk and risk reduction of major coronary events associated with contemporary breast radiotherapy.JAMA Intern Med. 2014; 174: 158-160Crossref PubMed Scopus (38) Google Scholar Information about heart and lung dosimetry from the IMPORT HIGH trial will probably be shared in a future publication. Thousands of patients have since been successfully treated with a concomitant boost approach in the USA. The New York University pilot contributed to the design of NRG RTOG 1005, another non-inferiority trial comparing sequential boost breast radiotherapy (23–32 visits) with a concurrent boost approach (15 visits). Preliminary findings with a median follow-up of 7·3 years were presented in 2022 at the American Society for Radiation Oncology's 64th annual meeting and showed non-inferiority for breast recurrence.5Vicini FA Winter K Freedman GM et al.NRG RTOG 1005: a phase III trial of hypo fractionated whole breast irradiation with concurrent boost vs conventional whole breast irradiation plus sequential boost following lumpectomy for high risk early-stage breast cancer.Int J Radiat Oncol Biol Phys. 2022; 114: S1Summary Full Text Full Text PDF Google Scholar While the scientific community is awaiting the final results of NRG RTOG 1005, the data from IMPORT HIGH are changing practice worldwide and are an important step towards applying hypofractionation solutions with a concomitant boost to the tumour bed in breast cancer radiotherapy, merging the optimal outcome achieved by modern technology with convenience for patients. We declare no competing interests. Dose-escalated simultaneous integrated boost radiotherapy in early breast cancer (IMPORT HIGH): a multicentre, phase 3, non-inferiority, open-label, randomised controlled trialIn all groups 5-year IBTR incidence was lower than the 5% originally expected regardless of boost sequencing. Dose-escalation is not advantageous. 5-year moderate or marked adverse event rates were low using small boost volumes. Simultaneous integrated boost in IMPORT HIGH was safe and reduced patient visits. Full-Text PDF Open AccessChallenges for breast radiotherapy with SIB: the IMPORT HIGH trial – Authors' replyWe thank the authors for their positive comments regarding the IMPORT HIGH trial.1 The main points raised are addressed as follows. Full-Text PDF