HOTAIR and digestive system carcinoma: Subgroup analysis showed that HOTAIR expression was associated with OS of patients in all types of cancers, such as estrogen-dependent carcinomas (HR = 2.00, 95% CI = 1.25–3.21, P = .004), digestive system carcinomas (HR = 2.11, 95% CI = 1.56–2.85, P < .001), OSCCs (HR = 3.26, 95% CI = 1.53–6.95, P = .002), and respiratory system carcinomas (HR = 2.04, 95% CI = 1.34–3.11, P = .001) (Table 3).