Noh et al reported a significant association between high expression of HDAC2 and a poor prognosis of patients with hepatocellular carcinoma.39 Kawai et al found that HDAC1 affects breast cancer progression by promoting cellular proliferation, and it may be a potential target for therapeutic intervention.40 We used our own patient cohort as well as samples from TCGA database to show that higher expression of class I type HDACs, including HDAC1, HDAC2 and HDAC3, is associated with worse outcomes in patients with sarcoma. The gene discussed is HDAC1; the disease is breast cancer.