After the conclusion of the prescribed RT course, the RT-alone group had significantly lower rates of anemia (44.2% vs. 63.5%, p = 0.017) with higher mean (SD) Hb level of 12.9 (1.8) g/dL vs 11.98 (2.2) g/dL (p = 0.003), compared to cetuximab plus RT. The gene discussed is GSTM1; the disease is anemia.