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Abstract Background: While adjuvant 6-monthly zoledronate is widely used in patients with early-stage breast cancer (EBC), questions remain around optimal scheduling of adjuvant bisphosphonates. We reviewed quality of life and bisphosphonate-related toxicities observed within a prospective randomised trial. Methods: Patients with EBC were randomised to either a single infusion of adjuvant zoledronate (4mg IV) or to 6-monthly treatment for 3 years. Quality of life was measured using the EQ-5D-5L questionnaire (before and after each infusion and 6-monthly thereafter in the single infusion arm). Acute phase reaction (APRs) data was collected after each infusion and data on other bisphosphonate-related toxicities (hypocalcaemia, renal impairment, ONJ and atypical fractures) was collected 6-monthly for 3 years. Results: Between 21-Nov-2018 and 02-Apr-2020, 211 patients were randomized to either a single infusion (n=107) or 6-monthly (n=104) adjuvant zoledronate. While each zoledronate infusion was associated with a worsening QoL, the overall QoL was the same in the two study arms. APRs occurred in 75% of patients after receiving zoledronate. Other bisphosphonate-related toxicities were uncommon in either arm. Significantly more patients discontinued study treatment in the 6-monthly arm (30/104, 28.8%) compared with the single infusion arm (3/107, 2.8%) (p 0.001). The most common reason for study discontinuation was the occurrence of APRs, pain and malaise. Disease-free and overall survival rates were not significantly different in the study arms. Discussion: A single infusion of adjuvant zoledronate may offer patients a more convenient and better tolerate regimen than repeat infusions. APRs remain an important toxicity with repeat infusions of zoledronate, leading to increased rates of treatment discontinuation. Larger, definitive, trials comparing a single infusion with repeat treatments are required. Citation Format: Igor Machado, Lucas Clemons, Carol Stober, Gregory Pond, Arif Awan, Henry Conter, Demetrios Simos, Sukhbinder Dhesy-Thind, Mihaela Mates, Vikaash Kumar, John Hilton, Lisa Vandermeer, Mark Clemons. A randomised trial comparing 6-monthly dosing of adjuvant zoledronate with a single one-time dose in patients with early breast cancer (REaCT-ZOL): Quality of life and toxicity outcomes abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-13-01.
Machado et al. (Thu,) studied this question.