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