The results of one study questioned the specificity of the 8F1 antibody for the ERCC1 protein[21].Two studies found some disconcordance between primary and secondary tumors with regards to ERCC1 expression levels[23], [24], which raises the possibility that analysis of the primary tumor may lead to an incorrect approach for a metastatic tumor[24]. This evidence concerns the gene ERCC1 and neoplasm.