Genetic Study Could Predict Cancer Survival
New technology moving toward medical practice
WEDNESDAY, April 28, 2004 (HealthDayNews) -- A simplified version of a high-powered genetic technology may make it possible to tell how cancer patients will respond to treatment, researchers report.
A commercially available technique singled out six genes that predicted the survival of patients with large-B-cell lymphoma, a common form of blood cancer, a group at Stanford University School of Medicine reported in the April 29 issue of the New England Journal of Medicine.
The report described one of the first efforts to make medical use of a technology called DNA microarrays, which lets scientists examine the activity of thousands of genes in a tissue sample taken from a cancer patient.
The problem for doctors is that, for clinical purposes, it would be difficult to use microarrays because they are expensive and difficult to work with, according to experts.
So the researchers turned to another type of screening called real-time PCR, which allows researchers to look more closely at a gene's activity. The real-time PCR assays used in this study were developed by Applied Biosystems, a California biotechnology company. PCR stands for polymerase-chain-reaction.
"They focused on 36 genes that others had shown by DNA microarrays to have prognostic information in lymphoma," said Mark Wechser, a staff scientist at Applied Biosystems. "Some genes are more linked with death, and they picked the six with the strongest links."
The study used tissue samples taken from 66 patients at the time they were diagnosed with lymphoma. Grimly, the researchers linked the level of activity of the genes to the deaths of patients.
It is an important study because some skeptics have said DNA microarrays might never be applied to cancer treatment, said Dr. Joseph M. Scandura, an attending physician in the leukemia service at Memorial Sloan-Kettering Cancer Center in New York City who has done research on the technique.
"There haven't been any reports about clinical utility to come out yet," he said. "This study shows that the information from DNA microarrays can be used in clinical decision-making, using a product that is commercially available."
Admittedly, the report describes only "an incremental step" toward the use of the genetic technology in medical practice, Scandura said. But he did envision some major benefits if and when it comes into common use.
Cancer drug therapy saves lives but can have some severe side effects, he said, and the doctor "has to weigh the benefits against the toxicity you know is coming."
If the genetic analysis shows that a patient has only a small chance of survival, "you might not put him through conventional chemotherapy," Scandura said. "Or you might try a different, experimental chemotherapy."
The news in the Stanford report is that "they show that what they tried to do is approachable by current medical center laboratories, not just research laboratories," Scandura said. "Microarrays are not ready for use in clinical laboratories, so let us get something we can use today."