Abstract PS4-10-29: Diverse adjuvant treatment in triple-negative breast cancer patients with residual disease after neoadjuvant chemotherapy: A single center real-world study

Abstract Background: Triple-negative breast cancer (TNBC) patients exhibiting residual disease post-neoadjuvant chemotherapy are associated with a poor prognosis. The CREATE-X study indicates that capecitabine adjuvant therapy benefits these patients, particularly the TNBC subgroup, and is now guideline-recommended. However, there's a lack of real-world data in China. This study aims to present the real-world adjuvant treatment status of TNBC patients with residual disease after neoadjuvant therapy. Methods: This study included TNBC patients with residual disease after neoadjuvant chemotherapy at the Cancer Hospital, Chinese Academy of Medical Sciences, from July 2008 and December 2024. Patients were categorized into capecitabine, intravenous chemotherapy, and no chemotherapy groups based on adjuvant treatment. Survival outcomes were compared among the groups, with a multivariate Cox model adjusting for confounders. Stratified analyses were performed using Neo-bioscore(NB) and residual disease burden. Results: This study included 340 patients, median age 47.4 years (20-76), 61.8% of patients were premenopausal. 120 received capecitabine-containing regimen, 118 had intravenous chemotherapy, 102 without adjuvant chemotherapy. The baseline characteristics were generally balanced among the three groups. In the capecitabine group, 63.3% (76/120) of patients received only capecitabine, and 36.7% (44/120) received intravenous chemotherapy followed by capecitabine. In the intravenous chemotherapy group, 39.8% (47/118) received the anthracycline plus cyclophosphamide (EC) regimen, 36.4% (43/118) the taxane plus carboplatin(TCb) regimen, and 11.0% (13/118) the anthracycline plus taxane(AT) regimen. The median follow-up time was 37 months. The 3-year DFS for the capecitabine group, intravenous chemotherapy group, and no chemotherapy group were 81.5%, 64.3%, and 70.5%, respectively, and the 3-year OS were 88.4%, 81.0%, and 74.5%, respectively. After adjustment by multivariate analysis, compared with the no chemotherapy group, the capecitabine group could significantly reduce the risk of disease recurrence and death (No chemotherapy vs. Capecitabine: DFS HR=1.92, P=0.032; OS HR=2.51, P=0.026); compared with the intravenous chemotherapy group, the capecitabine group could significantly reduce the risk of disease recurrence (Intravenous chemotherapy vs. Capecitabine: DFS HR=1.84, P=0.037). Stratified analysis for patients with NB≥5 showed the capecitabine group had better DFS than the no chemotherapy and adjuvant chemotherapy groups, with 3 - year DFS rates of 73.2%, 47.4%, and 46.5%, respectively(Capecitabine group vs. No chemotherapy group, Log-rank P=0.043; Capecitabine group vs. Intravenous chemotherapy group, Log-rank P=0.043), and the OS was also significantly better than that of the no chemotherapy group, with 3-year OS of 84.0% and 53.6%, respectively (Log-rank P=0.012). In patients with NB