Abstract P1-10-13: Economic comparison of standard external beam whole breast (WBI) versus accelerated partial breast irradiation (ABPI) in postmenopausal women with early-stage breast cancer. Results from the French SHARE randomized trial

Abstract Purpose: The economic evaluation reports the incremental cost utility ratio and budget impact of APBI vs standard external beam WBI for the treatment of post-menopausal women with early stage breast cancer. Methods and materials: We compared 488 women in the standard arm (1 fraction per day delivered 5 days per week over 3 or 6/6.5 weeks) to 490 women in the ABPI arm (ten fractions delivered twice per day over one week). We took the perspective of the healthcare system, a 3-year time horizon; the outcomes were quality adjusted life years (QALYs). QALYs were calculated from the EQ5D5L questionnaires at baseline, 3 months, 6 months, 12 months and yearly after irradiation; scores were converted into utilities using the French value set and QALYs computed with the area under the curve approach. Measures of within-trial use of hospital resources were based on routine hospital data via patient-level information. We used the itemized and DRG cost data from each individual patient. Transportation costs were added in a sensitivity analysis. A 2.5% discount rate was applied to costs and QALYs. An incremental analysis with differences in costs and QALYs was performed to calculate the cost utility ratio. Bootstrapping was used to quantify uncertainty on the joint distribution of costs and outcomes, and 1,000 paired estimates of mean differential costs and QALYs were reported on a cost-effectiveness plane. A budget impact analysis based on incidence of breast cancer estimates was added. All analyses followed the intent to treat principle. Results: Cost and utilities were available for the entire population. Costs and QALY results are presented in table 1. The 2 925 € (95% IC, -3 364 €; - 2 452 €) significant difference in total costs favoring ABPI was driven by the difference in radiotherapy costs and partly by lower transportation costs. No significant difference was found in QALYs. Figure 1 shows the uncertainty of the joint distribution of costs and QALYs. All replication are in the lower half of the plane indicating that ABPI is cost saving with QALYs distributed on each side of the vertical axis indicating equal distribution of QALYs. would be eligible for treatment with ABPI. The uptake of ABPI for 16% of these women would result in a 16 million€ cost saving. Conclusions: At three years, ABPI for the treatment of postmenopausal women with early-stage breast cancer was found to be cost saving, with no difference in outcome measured by QALYs. Table 1. Figure 1. Citation Format: Alicia Le Bras, Yazid Belkacemi, céline Bourgier, Isabelle Gabelle-Flandin, Adeline Petit, Philippe Guilbert, Julien Geffrelot, Christian Carrie, Eleonor RIVIN DEL CAMPO, Chantal Hanzen, claire charra-brunaud, Guillaume Auzac, Thomas Lacornerie, Jérôme Lemonnier, Eric Lartigau, Isabelle Durand-Zaleski. Economic comparison of standard external beam whole breast (WBI) versus accelerated partial breast irradiation (ABPI) in postmenopausal women with early-stage breast cancer. Results from the French SHARE randomized trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-10-13.