p16(INK4a) immunocytochemical analysis is an independent prognostic factor in childhood acute lymphoblastic leukemia

We investigated the prognostic value of p16(INK4a) immunocytochemistry (ICC) analysis in 126 cases of newly diagnosed childhood acute lymphoblastic leukemia (ALL). The incidence of negative p16(INK4a) ICC was 38.1% and was more frequent in T-lineage ALL. Overall survival (OS) and event-free survival (EFS) were significantly higher in patients with positive p16(INK4a) ICC than in patients with negative ICC (6 years OS, 90% versus 63%, P =.0014; 6 years EFS, 77.8% versus 55%, P =.0033). The p16(INK4a) ICC remained a significant prognostic factor within the subgroup of B-precursor ALL. Multivariate analysis showed that negative p16(INK4a) ICC was an independent prognostic factor for OS (relative risk [RR], 3.38; P =.02) and EFS (RR, 2.49; P =.018). Sequential study showed that p16(INK4a) expression remained stable during first relapse in most patients. These findings indicate that p16(INK4a) ICC is an independent factor of outcome in childhood ALL.