The pooled analysis of the relationship between HOX proteins and the depth of tumour invasion showed that HOXD10 indicated a low T category (HOXD10: OR = 0.20, 95% CI: 0.09–0.41), while HOXA13, HOXC6, HOXB7 and HOXA1 were related to a high T category (HOXA13 (2013): OR = 4.18, 95% CI: 1.75–10.01; HOXA13 (2018): OR = 1.90, 95% CI: 1.08–3.35; HOXC6: OR = 3.55, 95% CI: 1.11–11.31; HOXB7 (2015): OR = 3.44, 95% CI: 1.32–8.95; HOXB7 (2017): OR = 10.14, 95% CI: 4.36–23.58; and HOXA1: OR = 2.03, 95% CI: 1.18–3.48) (Fig. 5a). The gene discussed is HOXC6; the disease is neoplasm.