We observed pronounced myelotoxicity and a durable complete response in one HNSCC patient treated with both CDDP (100 mg/m2) and RT, which was attributed to inherited deficiency in CDDP detoxification (GSTT1 null genotype), deficiency in repair of CDDP cellular damage (MSH3 1045ThrThr), and increased apoptosis induction during CDDP cellular damage (GSTP1 105IleIle)12. This evidence concerns the gene MSH3 and head and neck squamous cell carcinoma.