Analysing the DNA of a tumour provides opportunities to target treatment in several types of cancer, with potential to both improve response and avoid harmful side-effects. For example, identification of an EGFR mutation increases confidence that the cancer will respond to a drug called gefitinib.
The quality of genomic data has been found to be much improved if DNA is extracted for sequencing from fresh-frozen rather than FFPE tumour samples. This has implications for all clinicians and scientists involved in tissue collection.
Advances in molecular technology mean that it is now feasible to obtain the entire sequence of DNA of a cancer cell within a few days and at an achievable cost. Panel tests allow us to analyse a number of genes concurrently. In addition to looking for individual gene mutations, which can predict whether a patient is likely to respond to a targeted therapy, we can also look at the overall pattern of mutations in a cell, which can give us important information about the underlying biology of the cancer.
We have now seen the advent of technologies that can detect circulating tumour DNA for some cancer types. This can be used to identify potential targets for treatment, for example EGFR mutation status in non-small cell lung cancer. Research suggests that this may offer the potential to monitor some individuals for cancer recurrence.
Clinical trials of new targeted anti-cancer drugs are increasingly being designed so that they are open to patients with a range of tumour types as long as they share specific DNA mutation profiles, instead of being used for just one tumour type.