ERCC6 and carcinoma: Polymorphisms in ERCC6 gene (codon 1097), especially the Val/Val homozygous genotype, occurred with the higher frequency in muscle-invasive tumors as compared to non-muscle-invasive ones, and polymorphic variants in the XPD (codon 751) and ERCC6 (codon 399) genes manifested the trends resembling effects of the XPD Asp312Asn polymorphisms with respect to T ≥ 2 high grade tumors as compared to T ≥ 2 low grade carcinomas.