You're leaving out all choices in your decision pipeline.
If you screen positive, you can elect to have a biopsy or scan.
If your results come back inconclusive, you can elect to pursue surgical (or other) intervention.
That's what medicine is: a selection from among potential procedures, given the information at hand, informed by previous outcomes in similar or applicable situations.
In this case, we simply have more information. If said information turns out to have limited predictive power on the ultimate occurance of cancer, that will be incorporated into detection and treatment practices.
But the important thing is having more information than we had before.
If the patient were a robot, this would make sense. But people are easily scared, especially by the word "cancer," and fright can lead to bad decisions. And this is a decision that's made by individuals, including the doctors, who just want to take the "safe" option.
For example, the United States Preventative Services Task Force, which effectively decides the preventative procedures covered by Medicare and Medicaid, recommended against routine prostate specific antigen testing for prostate cancer in 2012. They backed that up with data on mortality and unnecessary procedures. Prostate doctors around the country flipped out. The doctors are focused on helping their individual patients. That's good, but it keeps them from seeing the overall harm to the entire population.
If you screen positive, you can elect to have a biopsy or scan.
If your results come back inconclusive, you can elect to pursue surgical (or other) intervention.
That's what medicine is: a selection from among potential procedures, given the information at hand, informed by previous outcomes in similar or applicable situations.
In this case, we simply have more information. If said information turns out to have limited predictive power on the ultimate occurance of cancer, that will be incorporated into detection and treatment practices.
But the important thing is having more information than we had before.