Detection and quantification of mutations in the plasma of patients with colorectal tumors

Abstract

The early detection of cancers through analysis of circulating DNA could have a substantial impact on morbidity and mortality. To achieve this goal, it is essential to determine the number of mutant molecules present in the circulation of cancer patients and to develop methods that are sufficiently sensitive to detect these mutations. Using a modified version of a recently developed assay for this purpose, we found that patients with advanced colorectal cancers consistently contained mutant adenomatous polyposis coli (APC) DNA molecules in their plasma. The median number of APC DNA fragments in such patients was 47,800 per ml of plasma, of which 8% were mutant. Mutant APC molecules were also detected in >60% of patients with early, presumably curable colorectal cancers, at levels ranging from 0.01% to 1.7% of the total APC molecules. These results have implications for the mechanisms through which tumor DNA is released into the circulation and for diagnostic tests based on this phenomenon.colorectal cancer ͉ plasma DNA ͉ tumor suppressor gene ͉ circulating DNA ͉ diagnosis

The value of mutational profiling of the cytocentrifugation supernatant fluid from fine-needle aspiration of pancreatic solid mass lesions

“…34 An increased amount of cell-free DNA can be an indicator of malignancy. 35,36 The presence of circulating cell-free tumor DNA corroborates the shedding of this DNA into the local extracellular space that is sampled along with the cells in an FNA procedure. The concept of studying this local extracellular DNA is a novel one for the study of pancreatic cancer and can complement cellular DNA analysis especially in the cases where scarce or no cellular material is present in the smears.…”

Untitled

“…Alleles can be distinguished by hybridization to allele-specific probes with different dyes or single nucleotide extension. So far, BEAMing has been used for detection and relative quantification of sequence variants such as SNPs and mutations (Diehl et al, 2005). In the latter report the sensitivity to detect mutations was increased by preamplifying DNA from plasma prior to emPCR.…”

PCR digitale en micro-compartiments

“…L'ADN libre tumoral circulant portant des altérations spécifiques de la tumeur du patient peut cependant être très fortement dilué dans le pool d'ADN libre circulant provenant de la mort de cellules non porteuses de ces altérations. Il peut s'agir de cellules du microenvironnement tumoral comme de cellules saines de l'organisme [18]. Par exemple, l'ADN libre tumoral circulant peut représenter moins de 0,01 % de l'ADN libre circulant total pour des cancers à un stade précoce [14], et plus de 50 % pour des cancers métastatiques [13,19,20].…”