The basic approach to cancer screening in the US has been simple: Look for it early, and if you find it, get rid of it. That's the strategy that helped save thousands of lives from cervical cancer. And it's the strategy behind new screening tests for many other cancers.
But prostate cancer illustrates a flip side to that rote approach to cancer: Sometimes, it seems, cancer isn't something sure to be fatal. And sometimes the cure can be worse than the disease.
In these ambiguous situations, it's especially important to be mindful of your Decision Tree - to know exactly what your full range of options are, and what the consequences of every decision may be. It's something Tom Neville wished he'd known more about.
When Neville was told he had prostate cancer at age 54, he thought he knew exactly what the costs and benefits were: Unless he got treatment, he was going to die. As he saw it, he had two choices. He could undergo radiation therapy and hope to kill the cancer but save his prostate. Or he could have his prostate removed, which would be nearly certain to eliminate the cancer but carried significant risks of incontinence and impotence.
What Neville didn't realize at the time, though, is that though prostate cancer sounds horrible, the truth is that more than half of men have some cancer in their prostates by age 80, but less than five percent of those diagnosed actually die of the disease. These odds mean that, statistically speaking, the vast majority of men who have prostate cancer don't need treatment. In fact, as Neville says now, most men shouldn't even get a biopsy. What they don't know, he argues, probably won't hurt them.
The confusion starts with the screening test for prostate cancer itself--the PSA test. Short for prostate-specific antigen, PSA is a protein produced by the prostate gland. The PSA test measures the level of PSA in the blood. Some amount (around 1 nanogram per milliliter or more) is common, but a level of four or higher is considered suspicious of cancer (though some suggest that the suspicion threshold should be lowered to 3). As the number creeps over four, the reasoning goes, the probability rises that there is cancer.
Of course, the test doesn't actually measure cancer; it measures the amount of PSA, and there are all sorts of causes for a high PSA level besides cancer, starting with inflammation or infection. Still, a high PSA typically leads to a biopsy, and since so many older men have some trace of detectable cancer, it's not unusual to find something. But remember--just because there's cancer doesn't mean it's a lethal cancer. In other words, a high PSA level could prompt discovery of a coincidence, revealing a cancer that's probably never going to be a problem.
Tom Neville never properly understood this when he was considering treatment. Instead, when he got his diagnosis, he says, "I spent hours in the library. I was going cross-eyed reading research articles, trying to make sense of all this." What he did know was that his biopsy results had scared him. And no matter what the statistics were, "I had this emotional fear. I had a visceral reaction, to not want a cancer growing inside me. It was a get-it-out-of-me syndrome." And so on April 25, 2002, he had his prostate removed.
Even after his surgery, though, Neville, an engineer by training, kept poring over the research. Eventually he realized that he may not have needed surgery at all, given his low risk of dying from prostate cancer. But that information would have come in handy before his biopsy, before the word cancer had come into play with all its emotional associations. And he realized that it should be possible to give men more information sooner, so that they can assess their options before they get scared to death about a cancer inside them. Maybe the PSA test could start a process rather than compel a treatment. Maybe it would be possible to give people more choices, sooner.
What he came up with is Soar BioDynamics, a company that sells a decision-support tool for men who are trying to make sense of their PSA test results. The idea is to discern what, exactly, besides cancer could produce a high PSA level, so men don't move too quickly toward biopsy and removal, with all the latter's negative consequences. Using the information from a man's PSA test along with that from a few other easy tests and data points, Neville's tool calculates the most likely scenarios for what's happening inside a man's body, ranging from an enlarged prostate, to an infection, to a lethal cancer. The calculations are presented as probability scores for diagnoses. (The tool is a kind of nomogram -- a decision-making tool that combines individual information with best thinking from scientific research to create a personalized recommendation. They're a powerful idea for personalized medicine and you can read more about them here).
"We can cut way down on the false positives and eliminate detection of the cancers that aren't progressing. You want to catch the bad stuff but ignore the stuff you don't need to know about," he says. "Instead of a biopsy and surgery, maybe you just need to take an aspirin to cut down on the inflammation, or take antibiotics to take care of an infection."
Neville, who considers himself an acolyte of Clayton Christensen, is especially proud of how the Soar system has automated expertise. The computer model is based on published research, the same papers that made Neville scratch his head in the library back in 2002. But in this case, it customizes the research, flipping it from an abstraction into something tailored to an individual's circumstances. It turns this great heap of science into a basis for making clearer decisions.
"The issue isn't just what decisions you make, but what order you make them in," says Neville. "We're trying to switch the order of events. There's all this stuff driving people toward biopsy and treatment. We'd like to eliminate the unnecessary biopsies and only go to the expensive experts when it's highly warranted. We're not trying to do away with screening. The PSA test can be a valuable test; there's a lot of information in there. But it's important to know what the test actually shows."
Follow Thomas Goetz on Twitter: www.twitter.com/tgoetz
Loading comments… 
