RB1 and adenocarcinoma: In adenocarcinoma or p16INK4-negative tumors, the positive RB1 expression was also associated with the unfavorable outcomes (RR = 2.833, 95% CI: 1.532–5.239; P < 0.001; and RR = 3.273, 95% CI: 1.632–6.562, P < 0.001, resp).