New developments and technologies in hereditary cancer

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Published: 14 Dec 2015
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Dr Johnathan Lancaster - Chief Medical Officer of Myriad Genetics, Salt Lake City, USA

Dr Lancaster talks to ecancertv at SABCS 2015 about the myRisk® Hereditary Cancer test.

This test consists of a 25-gene panel that identifies an elevated risk for eight important hereditary cancers: breast, ovarian, endometrial, prostate, gastric, colorectal, pancreatic and melanoma.

Dr Lancaster notes that one of the potential barriers to testing for hereditary cancer is that it may cause distress to the individual being tested and so some patients and clinicians may be wary. Interim data on several hundred patients suggests, however, that this does not appear to be a significant problem with the use of the myRisk® test and patients noted that they were quite pleased that they agreed to being tested and had no regrets.

He also discusses the advantages of testing for multiple rather than single genes for identifying different risk categories of patients, and how 40% of mutated genes in breast cancer appear over the age of 45 years so using that age as a cut off would mean missing a lot of women who may go on to develop the disease or secondary cancers.

The other exciting data that will be presented this year relates to our 25 gene panel, myRisk. One of the challenges clinicians have faced in the clinic to date in hereditary cancer panel testing in general is uncertainty as to the impact that hereditary cancer panel testing may have on stress levels or distress with patients. We present this year some interim analysis of several hundred patients who have been evaluated both at the time of testing and three months subsequent and the early returns on that analysis suggest that there is, in fact, no increase in distress associated with panel testing and, in fact, the vast majority of patients were quite pleased that they went through with testing and had no regret.

This is impactful to clinicians who are practising medicine and considering testing patients because it removes a potential barrier to counselling patients and recommending testing with the long-term objective, of course, of preventing cancer.

One of the powers of new technology in the hereditary cancer testing space relates to the use of panels. Rather than trying to predict which patient has a mutation in which gene, recent data suggests that it’s actually impossible to predict with a high level of accuracy which patient should be tested for which gene. In other words, you can’t pick which genes to test for. Panel testing provides us with the opportunity to identify which patients are at highest likelihood to develop a malignancy based upon hereditary cancer risk.

How do you identify which patients to test?

Current guidelines for genetic testing in the hereditary cancer space use traditional biomarkers or traditional clinical markers to identify which patients to test. These would be patients that develop cancer at a young age, patients who have developed multiple cancers, or patients that have a strong family history or even have specific cancers – triple negative breast cancer or ovarian cancer. We’ve used these clinical biomarkers to date to identify which patients are most likely to carry a genetic susceptibility. What we’re learning in testing now we’ve tested over 135,000 patients with our 25 gene myRisk panel is that although you do indeed identify mutations in those patients we miss an opportunity, we miss mutations if we just use, for example, BRCA1 or BRCA2 to be tested when in fact we are now recognising that you increase the yield of mutations detected if you use a panel.

In fact, supportive of that concept is the fact that in our presentation this year we’re able to demonstrate that 40% of the mutations identified in patients with breast cancer actually occurred in patients over age 45, meaning that if we use age 45 as a strict cut-off for testing we miss a substantial proportion of mutations. These are mutations that could cause second cancers in those patients or cancers in other family members who are related to that patient. It’s a real missed opportunity, it’s a public health issue whereby we’re missing an opportunity to prevent cancers more globally.

Are the tests going to be expensive?

No, in fact that out of pocket test cost for the vast majority of patients tested with the panel versus with gene specific testing is no different.