A new study in the New England Journal of Medicine concludes: Among men with localized prostate cancer detected during the early era of PSA testing, radical prostatectomy did not significantly reduce all-cause or prostate-cancer mortality, as compared with observation, through at least 12 years of follow-up. This will come as no surprise to readers of this site. The issue of prostate cancer, its diagnosis and treatment, have been discussed here many times. The belief that screening for this disease carries a benefit will not die even after a stake has been hammered through its heart. It appears hard wired into the brain of every urologist in the country.
Consider the editorial that accompanied the paper cited above.
Three important studies published in the Journal during the past 3 years have addressed key issues related to prostate cancer. Two articles described large trials of prostate-specific antigen (PSA) screening and reached opposite conclusions regarding the impact of screening on the risk of death from prostate cancer. In this issue of the Journal, Wilt and colleagues report the results of a study that asked whether radical prostatectomy, as compared with observation, improved survival among men with prostate cancer. Collectively, these three studies suggest that a national focus on PSA screening and treatment for prostate cancer may have a marginal benefit on the lifespan of men but at a considerable cost. Nonetheless, there was a 44% reduction in prostate-cancer mortality between 1993 and 2009. How can this be, if screening and treatment do not reduce deaths from prostate cancer? One explanation could be the flaws of the studies themselves. The underlining is mine.
Another explanation is that the editorialists have not adequately analyzed the data. The graph below presents the complete mortality data for cancer in men dating back to 1930.
As you can see prostate cancer mortality has indeed dropped since 1993. But note that before that time it had steadily risen since 1930 with a sharp increase starting about 1985. Why? I don’t know and neither does anyone else. Mortality patterns commonly change spontaneously for unapparent reasons. The morality from prostate cancer today is still considerably higher than it was in 1930. The second of the two editorialists (Dr Tangen) is an epidemiologist and should have at least considered the possibility, since early diagnosis and treatment of this disease doesn’t seem to convey a benefit, that the changing patterns of mortality could be spontaneous. Deciding on the basis of selective analysis of the mortality data that something was wrong with the outcome studies seems more wishful thinking than a dispassionate scrutiny of all the pertinent literature. Actually, it’s an example of a faulty syllogism; ie screening and treatment of prostate cancer doesn’t work, but the death rate is going down, therefore screening and treatment do work. The first author of the editorial is a urologist and will likely find it hard to consider that PSA screening is not beneficial.
For comparison look at the morality rates for stomach and lung cancers. Both have fallen spectacularly for reasons unrelated to diagnosis and treatment. We know why lung cancer rates are declining – people smoke less. The reason for the fall in stomach cancer deaths is that almost no one gets the disease anymore. There are only speculative reasons for this marked decline in incidence. If you are unlucky enough to get the disease the treatment today is just as bad as it was eight decades ago.
