A little over two years ago, a friend warned me about getting a glimpse at my possible future through one of those new-fangled genetic tests. What if I discovered that I had a good chance of getting a bad disease?

“You’ll obsess about it and spend all your time worrying,” she predicted. I ignored her advice and got the test. A few months later, I learned that I’m at higher risk — maybe — of prostate and colon cancer. My life went on without extra stress or, for that matter, any major changes in how I eat and exercise.

It turns out lots of other people did exactly the same thing: nothing. Last week, The New England Journal of Medicine published the results of a Scripps Health study of more than 3,600 people who took controversial genetic tests designed to provide insight into our medical futures. The study, which acknowledges that the tests might be worthless, sought to follow us to see what we did next: Would we be overcome by anxiety? Would glimpses at our fates change our behaviors?

The good news: people generally didn’t freak out when they got the results. The bad news: people generally didn’t do anything differently afterward. “Little Benefit, Little Risk,” said the headline last week on WedMD.com.

“The bottom line is there appears to be nothing to be terribly afraid of and nothing to be gained from these tests in the short term,” bioethicist Ana Iltis of Wake Forest University told WebMD. “But the findings also suggest that if we are interested in promoting healthy behaviors, this is probably not the way to do it.”

By the numbers, 3,639 people got tested and 2,037 followed up by taking online surveys. More than 97 percent of participants reported no “clinically significant” extra stress after getting their test results. Overall, the participants didn’t report eating less fat or exercising more either. (Or, for that matter, eating more fat or exercising less.)

I wrote about my genetic test in a two-part series in 2008 and 2009. “I’ve signed a 5,600-word consent form, coughed up $300 and sacrificed my saliva,” I wrote in the first story. “Now it’s time to get a peek at what my DNA says about my life ahead.”

The other participants and I got a discount on the test, and in return we agreed to take online surveys and be monitored for the next 20 years. My results came a few months later with the news that I’ve got a 10 percent risk of developing colon cancer. My risk is higher risk than 96 percent of men of European ancestry, judging only by my genes. (The test only looks at the DNA I’m born with and doesn’t take into account any other factors, like the food I eat or the air I breathe).

My risk of getting prostate cancer was higher than normal too: It was at 26 percent instead of an average of 17 percent among European-descended men.

None of this guarantees that I’ll get any of these diseases or even that these numbers are accurate. As the study itself notes, genetic testing has “uncertain clinical validity and utility.” That’s a jargony way of saying that no one really knows if these tests can actually provide guidance into the medical risks facing people. The study is even more blunt: “screening decisions that are based on the results of such tests may be ill considered.”

That means people — and by people I mean me — might not need to run out and get, say, a colonoscopy or a prostate antigen test because a genetic test suggests their risk of colon cancer or prostate cancer is higher than normal.

Not surprisingly, experts question whether people should bother buying at-home genetic tests so they can get these same kinds of uncertain results. At least one state, New York, doesn’t allow companies from selling the tests directly to consumers, and the federal government is worried about oversight of the tests.

Unlike many participants in the study, I did mention the results to my physician. I’m not old enough yet to need extra screening for prostate or colon cancer, but it did cross my mind that I might want to get screened earlier than usual. But even that level of caution may not be needed, since there’s no history of either kind of cancer in my family.

A better diet and more exercise should help me reduce the risk of a variety of diseases. But I knew that before I took the test, just like everyone else. Doing something about it remains as difficult as ever, and that’s the toughest medical test of all.

Please contact Randy Dotinga directly at randydotinga@gmail.com and follow him on Twitter: twitter.com/rdotinga.

Randy Dotinga is a freelance contributor to Voice of San Diego. Please contact him directly at randydotinga@gmail.com...

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