Is “clinically insignificant adenocarcinoma of the prostate” a viable diagnosis?
Posted Sep 28 2008 5:40pm
In a recent paper on development of (yet another) nomogram designed to predict the probability of prostate cancer, the authors begin by stating the following:
Overtreatment of prostate cancer … is a concern, especially in patients who might qualify for the diagnosis of insignificant prostate cancer ….
This raises what may be a very interesting question: Can the prostate cancer community define and start to use “clinically insignificant prostate cancer” with accuracy as a diagnosis? If this is possible, could such a diagnosis be defined and regularly used with such compelling accuracy that men would believe it and decide they did not need to get treated?
It would appear likely that we may already have opportunities to start to use such a diagnosis — for example when low risk prostate cancer gets diagnosed in men who are at significant risk for death from other causes. ( Specific example: A 70-year-old male with a PSA of 2.7 ng/mL, no family history of prostate cancer, but a history of Type II diabetes starting in his late 50s, and a series of increasingly problematic cardiovascular conditions, including chronic heart failure. He somehow gets a 12-core biopsy that shows one small focus of Gleason grade 5 prostate cancer! Many would argue he should never have received the biopsy, but it happens frequently.)
At this time there are no diagnostic or statistical methods that are sufficiently accurate to predict with even 90 percent certainty that a man is not at risk from prostate cancer, given certain signs and symptoms. But there are all sorts of scenarios that can define men who are have a 90 percent probability of “clinically insignificant” prostate cancer.
Language is important. As a patient, there has to be a huge difference between being told
“You have prostate cancer, but it’s probably not going to affect you in your lifetime. I think we can just monitor this and make sure it never becomes a problem.”
as compared to being told
“You have clinically insignificant prostate cancer. The risks of treating this for a patient like you are high and include impotence, incontinence, and other serious problems. There is only a tiny chance that the disease might progress. We will monitor this risk and take action if we absolutely have to, but you don’t need to spend any time worrying about it. Come back again in 6 months and I’ll give you another DRE and PSA test.”
The authors of the abovementioned paper conclude by stating that, “Despite a high accuracy, currently available models for prediction of [clinically insignificant prostate cancer] are incorrect in 10% to 20% of predictions. … As a consequence, extreme caution is advised when statistical tools are used to assign the diagnosis of [clincially insignificant disease].” This is certainly the case. We are not at a point where we could accurately diagnose “clinically insignificant” prostate cancer in 95 percent of the men who actually have clinically insignificant disease. However, the question to be considered is, “Are we at a point where we could accurately diagnose clinically insignificant prostate cancer (and therefore use the term) in 95 percent of some groups of men who definitively have clinically insignificant disease?”