Immunohistochemical staining was performed according to the manufacturer’s protocol, using the primary antibody to CCDC34 antibody (ab122396) (Abcam, Cambridge, UK) at a dilution of 1: 500. The results were determined by light microscopy, with the immunostaining of each tissue section independently assessed by two histopathologists, as previously reported [8 (link)]. A visual immunoreactive score (IRS) was used for each case, ranging from 0–12, which was generated by staining intensity (SI) × number of stained cells (PP). The detailed scoring criteria for the SI (score, 0–3): 0 was negative, 1 was weakly positive, 2 was moderately positive and 3 was strongly positive. The detailed scoring criteria for the PP (score, 0–4): 0 was negative, 1 was 1–25%, 2 was 26–50%, 3 was 51–75%, 4 was 76–100%. If the IRS score was >4, the CCDC34 expression was defined as high; and if the IRS score was ≤4, the CCDC34 expression was defined as high.