GSTM1 and anemia (phenotype): When the analysis was restricted to those with pre-existing anemia, 25% had an improvement in the cetuximab plus RT group, which was significantly worse than RT-alone group (58.3%), p  < 0.001; with post RT mean (SD) Hb level of 10.9 (1.9) g/dL vs. 12.2 (1.8) g/dL, for both groups respectively, p = 0.001.