Whole-Genome Testing Could Become Diagnosis Tool
Case Studies of Cancer Patients Reveal Medical Potential of Quick Sequencing of Genomes
Testing Reveals Unsuspected Mutations continued...
“The syndrome carries a 90% lifetime risk of developing breast cancer and a 50% chance of developing cancer before the age of 40,” Pasche says. “It is a ticking time bomb.”
The discovery did not help the patient, but it could have major implications for her three young children, who have a 50% chance of inheriting the genetic error.
“We now know that aggressive screening and a variety of interventions, such as prophylactic mastectomy, can have a real impact on outcomes,” Pasche says.
Testing Helps Identify Treatment
The second case involved a young woman with acute myeloid leukemia.
The question was whether the woman needed a bone marrow transplant. Traditional testing left her doctors unsure about the answer.
A transplant was recommended based on the outcome of one test, which suggested that her odds of long-term survival were less than 15%.
Genome sequencing revealed a specific genetic error that was associated with a much better prognosis and a highly effective drug treatment.
“Without this information she might very well have received a bone marrow transplant,” Ley says.
In both cases, the whole genomic sequencing provided clinically useful information within six weeks. Technological advances will soon allow even faster sequencing.
“The technology is very close to being clinically applicable,” Ley says. “Many groups, including our own, are working to bring it into the clinical setting.”
Cost of Genomic Sequencing Dropping
He says whole-genome sequencing will initially benefit patients with high-risk cancers with no clear tools for identifying the best treatment.
One candidate is triple-negative breast cancer, which does not respond to targeted hormone therapies and tends to have a poor prognosis. Another is acute myeloid leukemia.
In an editorial accompanying the studies, Pasche writes that the cost of whole-genome sequencing has dropped 100-fold in less than three years. He writes that “the trend suggests that we are a lot closer to cost-effective, clinical genomics than most physicians realize.”
Lay predicts the cost will drop to around $10,000 to $15,000 within a few years.
The cheaper the cost, the more often the test will be performed. And greater use will mean more data to help researchers understand the mutations that influence susceptibility to cancer and other diseases.
“I think this will have enormous benefits from a research point of view for understanding a variety of inherited diseases,” Lay says.