A study testing all the DNA in the genome of cancer cells - the first of its kind - has identified individuals that may benefit from new treatments currently being tested in clinical trials.
Metastatic cancer - cancer that has spread from the region of the body where it first started, to other areas - is generally regarded as being incurable. In 2013, 39,620 women died from metastatic breast cancer in the US.
Progress in developing effective new chemotherapy or hormonal therapies for metastatic cancer has been slow, though there have been developments in therapies targeting specific genetic mutations in breast cancer.
"Until now genetic testing has only analyzed a limited number of genes to select which targeted drugs are suitable for individual patients and many treatment opportunities may be missed," explains Prof. Fabrice André from the Institute Gustave Roussy in France, whose study is published in The Lancet Oncology.
Prof. André and team think that this targeting of specific mutations or DNA copy numbers in breast cancer could shape how clinical trials - and ultimately new drugs - are designed.
The researchers took biopsy samples from 407 patients in France. They were able to conduct the whole-genome analysis in about two thirds of these women.
Examining the DNA from the samples, the team found that just under half (46%) of the patients in the study had a genomic alteration that could be targeted, while 39% had rare alterations for which no treatments currently exist.
"So far 55 (13%) of those enrolled (28% of those with targetable alterations) have been matched with new treatments being tested in clinical trials," writes Prof. André.
"This emphasizes the need to increase the range of drug trials. Our goal is to have 30% of patients in clinical trials testing therapies targeting the alterations identified in their tumors."
High expectations, but results may be less significant in daily practice
The authors of the study note that there is a very high level of expectation from patients and doctors about this kind of personalized medicine. The study enrolled 423 patients quickly - within 13 months - but the original projected time to gather patients for the study was 3 years.
It is also possible that this kind of personalized approach might be slightly less effective in daily practice than the study's results indicate. This is because the researchers handpicked patients who were most likely to provide a biopsy sample that was good enough to analyze. So, this kind of genome testing will not be effective in all patients.
Last year, Medical News Today reported on a new blood test that tracks fragments of DNA shed by dying tumor cells to assess how well women with advanced breast cancer are responding to treatment.