New guidelines on genetic testing and cancer

The American Society for Clinical Oncology has recently updated its guidelines on genetic and genomic testing for susceptibility to cancer. The entire guideline is available on line for any interested reader.

The role of genetic profiling in assessment of risk for prostate cancer is evolving. There are at least 25 specific SNPs (single nucleotide polymorphisms) that are now known to have an “association” with risk for prostate cancer, and there are commercial companies that will offer to analyze your DNA in order to assess your genetic risk for several forms of cancer (including prostate cancer) and other clinical conditions.

We have become increasingly aware of an expectation that genetic profiling will rapidly help us to know whether a specific individual is at real risk for prostate cancer. However, we are a long way, as yet, from having a decent appreciation of the distinction between a genetic risk for the development of cancer cells in the prostate and a genetic risk for the development clinically significant and therefore potentially lethal prostate cancer. And we are also a long way from  knowing exactly how accurate genetic testing is from being able to tell us the genetic risk simply for the development of cancer cells in the prostate. The problem, of course, is that for the vast majority of men, genetics is only one of several factors that may lead to development of clinically significant disease (along with things like environmental factors, diet, lifestyle, and a whole bunch of other things).

Just a few days ago, we reported on a paper that had identified a new SNP that seems to be associated with a high risk for clinically aggressive forms of prostate cancer. This is clearly a step in the right direction, but we are going to need proof positive that genetic testing really can identify men who, if left untreated, really are at high risk for clinically significant disease before the medical community can consider recommending specific genetic tests for prostate cancer risk. As we stated in our report on the recent article, the lead author was quoted as saying, “Our understanding of how the genome works is very limited.”

In the meantime, the new ASCO guideline gives a clear introduction to all of the issues related to appropriate role of genetic testing for cancer today. For those who want to spend their own money to have genetic disease profiling carried out, there are certainly companies out there that will do this. (Here is a link to information from one such company that has, at least, spent years trying to develop such tests using a sophisticated genetic testing model). Be aware, however, that your insurance isn’t going to pay for it; it is still extremely difficult to know exactly what to make of any results that such tests may offer you; and your doctor may not necessarily even know what to make of the data when you get it! Caveat emptor.

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