Recent advancements in the health sciences have paved a new path to screening for recurring breast cancer with more accuracy.
The Food and Drug Administration recently approved a microarray genetic test, called MammaPrint, that is designed to determine the likelihood of early-stage breast cancer recurrence within 5 to 10 years of initial treatment.
It is the first microarray test to be cleared by the FDA.
A microarray is a chip containing a collection of genetic probes that are used by scientists to simultaneously identify and evaluate the activity of a set of genes, said Stanley Nelson, professor of pediatrics and human genetics. The activity of certain genes can give scientists information on a cancer’s behavior and development.
Cancers take normal genomes, the genetic material of a person, and convert them into cancer genomes by turning genes on and off abnormally, Nelson said.
In interfering with a gene’s “on” or “off” configuration, the cancer can cause abnormal cell growth which in turn can suppress normal cell functioning.
MammaPrint is aimed at patients who fall into the “gray zone,” in which suitability of chemotherapy after initial treatment, usually surgery, is difficult to determine, said Marisa Weiss, a breast cancer oncologist at Lankenau Hospital in Philadelphia and the founder of nonprofit Web site BreastCancer.org.
If MammaPrint shows that a patient has a low risk of recurrence, the test may help in sparing her the difficulty of chemotherapy, while patients classified as high-risk could be identified as being more likely to benefit from chemotherapy, Weiss said.
There are FDA-approved genetic tests currently on the market that test a single gene at a time, but MammaPrint is the first FDA-approved device that tests multiple genes at once, Nelson said.
This is significant because the profiling of multiple genes allows researchers to understand a disease more completely, Nelson added.
The developers of MammaPrint said they have identified a set of 70 genes, which were correlated with breast cancer recurrence and its spread by studying the genetic profiles of a large sample of patients.
MammaPrint measures the level of activity in these 70 genes, in a surgically removed sample of a patient’s tumor and then uses this data to calculate a score that classifies patients as low-risk or high-risk for recurrence.
Five years after initial treatment, the test is 95 percent accurate that cancer will not return for patients classified as low-risk, while high-risk patients have a 23 percent chance that their cancer will return, said Dr. Steven Gutman, director of the FDA’s Office of In Vitro Diagnostic Device Evaluation in a statement.
Additionally, 10 years after first treatment, low-risk patients have a 90 percent chance that their cancer will not return, while high-risk patients have a 29 percent chance of recurrence, Gutman said.
While the data on MammaPrint is promising, doctors say they are wary of the practical applications of the test and note the need for further evidence from data on more patients.
“This test is a potentially new advance, but before we can really use it and make important treatment decisions with it, the studies on the treatment need to be statistically validated further,” Weiss said.
Some analysts say the implications of the FDA’s approval of MammaPrint may make it more likely for health insurance companies to cover the costs of the test.
Researchers are hoping that with the increasing insurance coverage, the use of the test will be more widespread and the additional data from its use can be used to improve and refine the test further.
As insurance companies cover more cases, the test would become more widespread and additional data would contribute to what is already known, which may help improve and refine the test further.
“There’s a movement for this now ”“ both on the insurance side and on the clinician’s side ““ because the more samples we have, the more confidence we have that we have the right representation of the total population,” said Yohan Lee, a graduate human genetics student.
In addition to breast cancer screening advantages, the approval of MammaPrint by the FDA also marks a new beginning for the use of microarray tests in medical practice.
“I think one exciting thing about having FDA approval for some of these tests, especially if they are permitting us to collect very large-scale information, is that the tools can and should be applied to all of us,” Nelson said.
“The FDA is starting to embrace the complexity of this testing, but it’s just beginning,” he added.
“It’s going to get more and more complex.”