Abstract PS3-09-11: Acceptability of adjuvant chemotherapy in women aged 70 and older after surgery for ER-positive HER2-negative breast cancer selected with a high genomic grade index: results from the ASTER 70s/Unicancer trial

Abstract Background: The first results of ASTER 70s were presented at the 2022 ASCO annual meeting and have been accepted for publication in the Lancet. After a median follow-up of 8 years, women aged 70 years and older who underwent surgery for luminal breast cancer did not derive any significant benefit in overall survival from adjuvant chemotherapy added to hormonotherapy when selected based on a high-risk genomic grade index (GGI) tumour. However, the acceptability of chemotherapy may vary with age. Methods: We report here the acceptability of chemotherapy in women randomized to receive chemotherapy (4 cycles of anthracycline- or taxane-based chemotherapy administered every 3 weeks) in addition to hormonotherapy, as assessed using a self-administered questionnaire designed based on a previous experience in a similar setting (GERICO 06 trial). After the last cycle of chemotherapy, patients were asked ‘to what extent the treatment was acceptable given the absolute additional benefit of 7.5% in terms of cure sought with chemotherapy”, as stated in the patient information sheet and informed consent form, and the main reason if they found the treatment unacceptable. They were also asked whether they would recommend such treatment to relatives or close friends facing a similar situation. The questionnaires were then administered then yearly for 4 years. Results: Of the 1,969 women screened for tumour GGI between April 2012 and May 2016, 58 (2.9%) withdrew their consent before GGI results and randomisation, while 1,089 (55%) with high-risk GGI tumours were randomized between chemotherapy and no chemotherapy. Of the 541 (49.7%) assigned to chemotherapy, 111 (20.5%) did not receive it for the following reasons: 23 (20.7%) refused chemotherapy, 22 (19.8%) withdrew consent, 8 (7.2%) for medical reasons, and 58 (52.3%) for unknown reasons. Of the 430 patients (79.5%) who started chemotherapy [44 (10.2%) stopped before the fourth cycle], 299 (69.5%) completed the first acceptability questionnaire at the end of chemotherapy, with 266 (95.3%) and 13 (4.7%) rating the chemotherapy experience acceptable and unacceptable, respectively, an assessment that was strongly associated with the occurrence of a serious adverse event during chemotherapy (15% and 46%, respectively, p<0.05). In addition, 242 (94.2%) said they would recommend the treatment to relatives if they were in the same situation. These rates remained stable over time until the fourth year of follow-up. Patient and tumour characteristics, quality of life scores at baseline, overall survival and invasive disease-free survival did not differ between patients who completed the acceptability questionnaire and those who did not. Factors reducing the acceptability of chemotherapy over time (from acceptable à not acceptable versus stable acceptable since the first post-chemotherapy assessment) were advanced age, a high Lee score (4-year mortality estimation) and low IADL. At baseline, low role functioning, low cognitive or social functioning, pain, dyspnoea, and loss of appetite had some impact on the acceptability of chemotherapy. Conclusions: It is difficult to assess the acceptability of a treatment, which depends largely on its safety and, consequently, its intensity in relation to increasing frailty with age. The acceptability of chemotherapy appears also to be influenced by factors such as age and quality of life, which must be taken into account when developing hypotheses in clinical trials, especially in elderly subjects. Citation Format: E. Brain, J. Henriques, F. Rollot, O. Mir, E. Bourbouloux, O. Rigal, J. M. Ferrero, S. Kirscher, D. Allouache, V. d'Hondt, A. M. Savoye, X. Durando, F. P. Duhoux, L. Venat Bouvet, E. Blot, J. L. Canon, H. Bonnefoi, T. Roque, J. Lemonnier, A. Latouche, M. Lacroix-Triki, D. Vernerey. Acceptability of adjuvant chemotherapy in women aged 70 and older after surgery for ER-positive HER2-negative breast cancer selected with a high genomic grade index: results from the ASTER 70s/Unicancer trial [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-09-11.