70 serious adverse events were reported in 39 ( 51 % ) of 76 patients who received chemotherapy plus cetuximab ( 34 events in 19 [ 25 % ] patients were treatment-related ) , whereas 41 serious adverse events were reported in 25 ( 35 % ) of 71 patients who received chemotherapy alone ( 20 events in 12 [ 17 % ] patients were treatment-related ) .