Objective:To explore the effect of tyrosine kinase inhibitor (TKI) dose reduction regimen in patients with chronic-phase chronic myeloid leukemia (CML) and its prognostic impact.Methods:A retrospective cohort study was conducted. The clinical data of patients with chronic-phase CML treated with reduced-dose TKI in the First Affiliated Hospital of Soochow University between January 2018 and December 2022 were collected. Patients were divided into groups based on Sokal score, European Treatment and Outcome Study long-term survival (ELTS) score, TKI drug classification and dose reduction, and treatment phase. The overall survival (OS), the cumulative incidence of major molecular response (MMR), the cumulative molecular recurrence rate and event-free survival (EFS) among patients in different strata were compared. Kaplan-Meier method was used for survival analysis.Results:Among 154 patients with chronic-phase CML, the median duration [ M ( IQR)] of reduced-dose TKI therapy was 35.4 months (34.9 months); Sokal score high-risk and low-/intermediate-risk groups comprised 20 cases (12.99%) and 134 cases (87.01%), respectively; ELTS score high-risk and low-/intermediate-risk groups comprised 14 cases (9.09%) and 140 cases (90.91%), respectively. Among 154 patients, 83 cases (53.90%) received imatinib therapy, while 71 cases (46.10%) received second-generation TKI; 138 patients (89.61%) maintained stable TKI dosing at the first dose level, and 16 patients (10.39%) maintained it at the second dose level. The induction therapy group comprised 33 patients (21.43%), while the maintenance therapy group included 121 patients (78.57%). The 3-year OS rate of all 154 patients was 90.6%. Patients in the Sokal score high-risk group demonstrated a lower 3-year OS rate compared to those in the low-/intermediate-risk group (64.1% vs. 96.7%) ( P < 0.001); patients in the ELTS score high-risk group had a lower 3-year OS rate compared to those in the low-/intermediate-risk group (62.9% vs. 95.8%) ( P = 0.002). There was no statistically significant difference in the 3-year OS rate of patients receiving the first dose level and those receiving the second dose level (90.6% vs. 90.0%, P = 0.478); there was no statistically significant difference in the 3-year OS rate of the induction therapy group and the maintenance therapy group (88.9% vs. 91.4%, P = 0.868). Among the 33 patients in the induction therapy group, all received the first dose level. After treatment, 28 achieved MMR, and 2 achieved molecular response 4.0 (MR4.0). The cumulative 1-year MMR rate of all patients in reduction therapy group was 95.8%, with a median time to MMR of 8.4 months; patients in the high-risk Sokal score group had a 1-year cumulative MMR rate of 50.0%, which was lower than that of the low-/intermediate-risk group (95.3%) ( P = 0.014); the median time to MMR was 14.7 months and 7.8 months, respectively. The cumulative 1-year MMR rate of patients treated with first-generation TKI was lower than that in those treated with second-generation TKI (65.0% vs. 100.0%, P = 0.034), and the median time to MMR of patients treated with first-generation TKI was longer than that those treated with second-generation TKI (9.1 months vs. 6.9 months). Among the 149 patients who achieved MMR, 5 experienced molecular relapse, resulting in a 3-year cumulative molecular relapse rate of 8.3%. In the Sokal score low-/intermediate-risk group, the 3-year cumulative molecular relapse rate (1.5% vs. 39.8%, P < 0.001), EFS rate (92.3% vs. 57.1%, P < 0.001), and OS rate (100.0% vs. 62.8%, P < 0.001) were better than those in the Sokal score high-risk group. The 3-year cumulative molecular relapse rate and 3-year EFS rate in patients receiving first dose level therapy were better than those in patients receiving second dose level therapy, and the differences were statistically significant (all P < 0.001). Conclusions:Patients with chronic-phase CML can still obtain good outcomes when receiving dose-reduced TKI, while the prognosis of patients in high-risk group is relatively poor. The choice of TKI and the dosage reduction should be individualized based on patients' characteristics.