Genetics, genomics, and improvements in the management of prostate cancer

Over the past few years we have seen a great deal of discussion of this or that new gene or single nucleotide polymorphism (SNP) or other set of genomic data and the potential of such information to improve the diagnosis or the prognosis of prostate cancer. It has even been suggested that some of the tests in development might be able to help to clearly differentiate between indolent and aggressive forms of disease. And maybe they can. But …

What we have not seen to date is a single prospective study that has compared the ability of any of these new genomic tests to that of the current prognostic standards (i.e., the Kattan nomograms, the Partin tables, and other well-established and well-documented tools) for prediction of clinical outcome based on common clinical and laboratory data.

You don’t have to take our word for this either. Look at this quote from a well-known and respected medical oncologist who specializes in the treatment of prostate cancer:

To convince me that a genomic test is useful, the investigators would have to compare the test to the best nomograms that utilize readily available clinical and laboratory parameters. Show me the data that this test is superior at risk stratification compared to nomograms as they are used at centers of excellence.

Oliver Sartor, MD, in The ASCO Post, May 1, 2011, p. 25

In our view Dr. Sartor has hit the nail right on the head. To demonstrate a true clinical value that will actually help a patient and his doctor to better manage an individual case of prostate cancer, genomic information needs to be able to significantly improve on the prognostic data we can easily generate today. He was being quoted in relation to information about a new genomic test being developed by Genomic Health, Inc. in partnership with researchers at the Cleveland Clinic.

There is absolutely no doubt that one or more gene-based tests that could really help to differentiate between men who had indolent as opposed to aggressive forms of prostate cancer would be immensely valuable. (Any test that could do this would be immensely valuable, gene-based or not.) However, gene-based tests that can not offer such clearly defined prognostic benefits had better be able to do something else of comparable significance.

Here is a list of genetic tests that might have real value in the management of prostate cancer:

  • A test that could clearly and prospectively identify truly indolent prostate cancer that would never need treatment
  • Tests that could clearly and prospectively identify forms of prostate cancer that would respond with a high degree of efficacy and safety to targetable forms of treatment (e.g., a test that could predict high levels of response to dutasteride or bicalutamide or abiraterone acetate or MDV3100)
  • A test that could clearly and prospectively identify the presence of micrometastatic prostate cancer

The opportunities available from genomics are considerable, but we will squander these opportunities if we don’t recognize that we already have good methods to make diagnostic and prognostic decisions based on older and much less costly technology. We need to use genomics to massively improve upon the currently available technology, not to replicate it.

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