Abstract: Objective To investigate the efficacy and side effect of different doses of decitabine in the treatment of elderly patients with myelodysplastic syndrome(MDS),and to analyze the correlation of the effect with TP53 gene mutation. Methods A total of 52 patients with MDS admitted in our hospital from April 2020 to May 2022 were enrolled in this study and divided into group A (receiving decitabine 20 mg/d × 5 d, n=28) and group B (receiving decitabine 10 mg/d × 10 d, n=24) according to the indications. The clinical efficacy, toxicity and side effects of the two groups after 6 cycles of treatment were compared, and the correlation of the efficacy with TP53 gene mutation was analyzed. Results The total effective rate was 39.3% in group A,compared with 37.5% in group B(P＞0.05). The incidence rates of grade 3-4 neutropenia, grade 3-4 thrombocytopenia, grade 3-4 anemia, infection, liver damage, fever and gastrointestinal reactions showed no statistical differences between the two groups (P＞0.05). The total effective rate in TP53 mutation group was 83.3%, compared with 12.9% in the wild type group, with significant difference(P<0.01). Conclusions The total effective rate and the incidence of adverse reactions of decitabine 20 mg/d × 5 d and decitabine 10 mg/d ×10 d shows no significant differences. The response rate in patients with TP53 mutation to decitabine is significantly higher than that of patients with wild-type TP53.

Key words: myelodysplastic syndrome, decitabine, TP53 mutation, effective rate