mechanism that removes the therapeutic platinum-DNA adducts from the tumor DNA. ERCC1 activity levels, being an important part of the NER common final pathway, may serve as a marker of general NER throughput. This has been suggested for patients with gastric, ovarian and bladder cancers. In Non-small cell lung carcinoma (NSCLC), surgically removed tumors that receive no further therapy have a better survival if ERCC1-positive than if ERCC1-negative. Thus, ERCC1 positivity is a favorable prognostic marker, referring to how the disease will proceed if not further treated. ERCC1-positive NSCLC tumors do not benefit from adjuvant platinum chemotherapy. However, ERCC1-negative NSCLC tumors, prognostically worse without treatment, derive substantial benefit from adjuvant cisplatin-based chemotherapy. High ERCC1 is thus a negative predictive marker, referring to how it will respond to a specific type of treatment. In colorectal cancer, clinical trials have not demonstrated the predictive ability of ERCC1 in oxaliplatin‐based treatment. Thus, European Society for Medical Oncology (ESMO) has not recommended ERCC1 testing prior to the use of oxaliplatin in routine practice. ERCC1 genotyping in humans has shown significant polymorphism at codon 118. These polymorphisms may have differential effects on platinum and mitomycin damage. Deficiency in cancer ERCC1 protein expression is reduced or absent in 84% to 100% of colorectal cancers, and lower expression of ERCC1 has been reported as being associated with unfavorable prognosis in patients undergoing treatment with oxaliplatin. The promoter of ERCC1 is methylated in 38% of gliomas, resulting in reduced mRNA and protein expression. The promoter of ERCC1 was located in the DNA 5 kilobases upstream of the protein coding region. Frequencies of epigenetic reductions of nine other DNA repair genes have been evaluated in various cancers and range from 2% (OGG1 in papillary thyroid cancer) to 88% and 90% (MGMT in gastric and colon cancers, respectively). Thus, reduction of protein expression of ERCC1 in 84% to 100% of colon cancers indicates that reduced ERCC1 is one of the most frequent reductions of a DNA repair gene observed in a cancer. Deficiency in ERCC1 protein expression appears to be an early event in colon carcinogenesis, since ERCC1 was found to be deficient in 40% of the crypts within 10 cm on each side of colonic adenocarcinomas (within the early field defects from which the cancers likely arose). Cadmium (Cd) and its compounds are well-known human carcinogens. During Cd-induced malignant transformation, the promoter regions of ERCC1, as well as of