PVR and lung cancer: Besides this, subgroup analysis demonstrated that the level of CD155 expression was significantly associated with OS in patients with breast cancer (pooled HR = 2.137, 95% CI = 1.448–3.154, P < 0.001), lung cancer (pooled HR = 1.706, 95% CI = 1.193–2.440, P = 0.003), and head and neck cancer (pooled HR = 1.470, 95% CI = 1.160–1.862, P = 0.001).