Can genomics help detect early cancer and monitor treatment effectiveness?
Many cancers, such as ovarian cancer and some kidney cancers, are typically only detected when they are relatively far advanced, because they may not be associated with noticeable symptoms in the earlier stages. One remarkable discovery in the past few years has been the finding that the DNA of solid tumor cells often can be found in the blood and detected using sequencing and other approaches.
The discovery of this circulating tumor DNA (ctDNA, that presumably occurs through the death of cancer cells whose contents are then released into the bloodstream) is important because it offers the possibility that a blood test with subsequent genomic sequencing or probe based approaches might be used for detection of “silent” early cancers.
Indeed, in a recent study designed to detect regions from 139 genes that frequently carry somatic mutations in non-small-cell lung carcinoma (NSCLC), ctDNA was detected in approximately 50% of patients with early (Stage I) NSCLC and in all of the patients with more advanced (Stage II–IV) NSCLC. This type of ctDNA assay is theoretically adaptable to many types of cancer, and it is likely that screening for ctDNA will become a standard component of cancer early detection in the future.
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