Objective:To investigate the clinical efficacy of histone deacetylase(HDAC)inhibitor chidamide combined with CHOP in the treatment of preliminarily diagnosed peripheral T-cell lymphoma(PTCL)and to analyze the factors influencing its prognosis.Methods:Clinical data were collected from patients who were preliminarily diagnosed with PTCL,but had not received radiotherapy or chemotherapy at the Affiliated Hospital of Nantong University between April 2012 and August 2022.The patients were divided into two groups,based on the frontline treatment regimen:the chidamide+CHOP group(n=20)and the CHOP group(n=24).The differences in clinicopathological characteristics between the two groups were compared by chi-square test or Fisher's exact test.Survival curves were generated by Kaplan-Meier method,and univariate survival analysis was conducted by Log-Rank test.Subgroup analysis was performed to assess the survival outcomes of patients in the chidamide+CHOP group,and interaction tests were conducted to assess the factors that might influence the difference in survival prognosis between the two groups.Results:The baseline levels of the two groups were comparable in age,gender,and tumor stage,but there were more AITL patients(70.8%vs 15%)and fewer PTCL-NOS patients(16.7%vs 30%)in the chidamide+CHOP group.Efficacy analysis revealed that the median PFS was significantly longer in patients treated with chidamide+CHOP(7 months vs 3 months,P=0.032),and their median OS was also significantly longer(20 months vs 6 months,P=0.004).Univariate prognostic analysis revealed that PTCL patients with B symptoms had significantly poorer PFS(P=0.053)and OS(P=0.065)than PTCL patients without B symptoms;and patients with elevated baseline LDH levels had a worse OS(P=0.056).Further subgroup analysis of efficacy revealed that,among patients with normal baseline serum ferritin levels,those in the chidamide+CHOP group had significantly better PFS compared with those in the CHOP group(95%CI[1.14,43.58]).The interaction test between serum ferritin levels and treatment regimens demonstrated statistical significance(P=0.042).Conclusion:The combination of chidamide and CHOP has survival benefits for patients preliminarily diagnosed with PTCL,and baseline serum ferritin levels may serve as a potential predictor for combination therapy.