CDC Study Assesses Genetic Testing's Impact on Health Outcomes
Some genomic tests developed to personalize medical decisions about cancer care are beneficial, while for others the evidence is uncertain and reliance on the test might even lead to poorer medical management of cancer in some cases, according new recommendation statements from an expert panel.
The statements appear in the January issue of Genetics in Medicine, the official peer-reviewed journal of The American College of Medical Genetics and published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
Genetic tests for tumor gene expression in women with early-stage breast cancer to detect those at risk for cancer recurrence, the panel wrote, are based on insufficient evidence to determine whether they offer any improvement in health outcomes. The panel also found insufficient evidence to recommend testing for variants of the gene UGT1A1 in patients undergoing chemotherapy for metastatic colorectal cancer to inform use of the chemotherapy drug irinotecan.
While the test might be useful in identifying patients at risk of side effects from the drug, reducing irinotecan dosage may be more harmful than the side effects, so the clinical utility of the UGT1A1 test is questionable, at best, it said.
On the other hand, genetic testing for Lynch syndrome, a hereditary condition that increases the risk of colorectal cancer, is useful to recommend screening relatives for the mutations that cause the syndrome and encouraging them to have regular colorectal cancer exams, the panel found.
"Our reviews of the evidence found that in some situations genetic testing may be helpful, but that in others, including for some genetic tests currently used in cancer care, there is not enough evidence available to determine the balance of benefits and harms," said Alfred Berg, M.D., M.P.H., chair of the working group that produced the recommendations. These recommendation statements are the most recent analyses from the Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group.
As the number of available genetic tests continues to increase, so do questions regarding their appropriate use. The EGAPP initiative was developed by the National Office of Public Health Genomics at the Centers for Disease Control and Prevention (CDC), with the goal of supporting evaluation of genetic tests and other genomic applications that are in transition from research to clinical and public health practice. The independent EGAPP Working Group based its recommendations on commissioned, systematic reviews of available studies addressing the validity and utility of specific types of genetic tests.
For more information, go to www.egappreviews.org.