20 January 2009
New recommendations were made regarding UGTA1A1 genotyping in patients with metastatic colorectal cancer (CRC) treated with irinotecan [EGAPP (2009) Genet Med. 11(1):15-20]; the use of testing strategies to identify Lynch Syndrome among newly diagnosed cases of colorectal cancer [EGAPP (2009) Genet Med. 11(1):35-41]; and the use of three specific tumour gene expression profiling tests in women with breast cancer [EGAPP (2009) Genet. Med. 11(1):66-73]. Summaries of the evidence leading to the recommendations, as well as an article describing the methods and process used by the EWG in collecting, analysing and grading evidence, are also available in this issue of the journal.
In formulating their recommendations, EGAPP begin by addressing a specific clinical scenario (since a single test may be used in different clinical scenarios). An analytic framework and key questions are formulated based upon this clinical scenario, allowing explicit literature searches to be carried out. Evidence in relation to the analytical and clinical validity and clinical utility of a genetic test is gathered along with a consideration of contextual issues in relation to the implementation of testing. Along with assessing the available evidence, this process also identifies gaps in research and the EWG as part of their assessment also describes studies which can contribute to the evidence-base.
The Working Group concluded that there was insufficient evidence for or against the routine use of UGTA1A1 genotyping in patients with metastatic CRC and the use of gene profiling tests in women with breast cancer. However, they felt that there was sufficient evidence to recommend offering genetic testing for Lynch Syndrome in those diagnosed with CRC. The lack of evidence on the clinical utility of UGTA1A1 genotyping and contextual issues demonstrating both benefits and harms of testing, meant that firm recommendations in favour or against this test could not be made. Insufficient evidence to balance the benefits and harms of tumour profiling in breast cancer also precluded a firm decision in relation to this test. In the case of testing for Lynch Syndrome, adequate evidence was available on the analytical and clinical validity as well as clinical utility.
Genetic tests can have a broad public health impact; however, with the increasing development of tests, policy makers need to consider their potential harms and benefits through an evidence-based mechanism prior to their use in clinical practice. This evaluation process requires information on analytical and clinical validity as well as clinical utility. However, due to the absence of a requirement for the formal evaluation of clinical utility, often this information is difficult to obtain. The lack of information on clinical utility has been highlighted many times by both EGAPP and the United Kingdom Genetic Testing Network (UKGTN). The requirement for formal evaluation of clinical utility in order to address this gap in knowledge has been highlighted by a PHG Foundation report on the evaluation of genetic tests and molecular biomarkers. The PHG Foundation has taken specific interest in the policy issues concerned with the evaluation and regulation of genetic tests, and has been closely involved in developing processes for so doing within the UKGTN.