This examination of two new mathematical modeling studies on the value of PSA testing accurately nails the problems in interpreting research of this nature and why it is difficult to draw firm conclusions. The reader is left with a broader understanding of different factors that might affect prostate cancer detection, including what is often called the “healthy user bias”–when those who undergo screening and/or treatments might be a healthier cohort of patients to begin with and it is that factor, not the decision to undergo screening/ treatment, that is the main reason for apparent improved survival. A Los Angeles Times story we reviewed on the same study didn’t provide this important context.
PSA testing is a highly controversial, polarizing subject whereby those who promote it, as well as those men who have been treated based on raised prostate specific antigen levels, become evangelists for early detection. Others who examine the randomized trials bring attention to the fact that men who undergo PSA testing are more likely to have their lives drastically altered, suffer the effects of treatment (including urinary incontinence and erectile dysfunction), in exchange for the small likelihood that their lives would be “saved.”
The lack of any cost information is one flaw to this article. Reminding the readers of the costs of PSA screening programs–in terms of the huge volume of medical services that it can catalyze (including the costs of the test itself, the drugs, surgeries, urology consultations, hospital and operating time, as well as the lost income for men who are recovering from treatment)–is a necessary part of the story.
There is good depth here discussing the benefits. Early in the story it indicates that “for a man in the U.S., the risk of dying of prostate cancer is about 2.5 percent. A mortality reduction of 30 percent would lower the death rate to 1.75 percent.” Later this is described in relative terms, saying that more frequent PSA screening “moved some prostate cancers from too-advanced-to-treat to treatable, reducing prostate cancer mortality by 27 percent to 32 percent over 11 years.”
Drawing from information produced by the USPSTF, the article concluded that the gains in prostate cancer detection “come at some cost to health, though: For every life saved, five men will be told they have cancer when in fact their abnormal cells would never grow, spread, or harm them. In other estimates, such “overdiagnoses” outnumber lives saved by 50-to-1.”
The one harm that is often overlooked in widely-promoted screening programs is the psychological harm that perfectly healthy people may experience when they have had a “cancer scare,” and that even though their life is unlikely to be saved, the worry, anxiety, depression and angst do exact a substantial life-altering toll that goes unmeasured.
This story superbly describes the quality of the evidence, emphasizing that this is not new research but it is new (and controversial) mathematical modeling and that there are a number of biases that can affect the interpretation of the results. This was a much stronger discussion of the evidence compared to the LA Times story we also reviewed.
There are no signs of the common type of disease mongering we sometimes encounter in commentary about PSA testing, where some will take data from one age cohort as proof to suggest that other age cohorts (ie: younger men) would also benefit from PSA testing.
A wide range of outside voices give this article depth and heft. The inclusion of voices of researchers who chose to remain anonymous reminds us of the very controversial and potentially career-altering aspects of this research.
However, as with the Los Angeles Times story, this story didn’t note the financial disclosures of the study authors, including the senior author, Ruth Etzioni, who disclosed she owns equity in a company developing medical imaging technology that it says could be applied in prostate cancer patients. Dr. Etzioni stated that she does not consider the equity ownership to be a conflict of interest, but considering that an increase in PSA screening would boost demand for more precise and less invasive follow-up testing, it appears that her company would benefit.
The study was funded by the National Cancer Institute. While that source does not raise any red flags, and the study stated that the funder had no role in the study, news stories are more informative when they note study funding.
This research is specifically about comparing the value of screening for prostate cancer vs not screening. New biomarkers and variations on the PSA test itself, along with other screening modalities, such as digital rectal exam, are not mentioned and were not addressed in the studies that are described.
It’s clear from the article that PSA testing is ubiquitous in America. Mentioning that it is covered by most insurers, and for those on Medicaid/Medicare, still would have been helpful, however.
The report of this study establishes, correctly, how it might expand our view of the value of PSA testing and reminds us that what is “novel” here is the interpretation of previous research.
This article clearly goes beyond what would have likely been the contents of a news release, particularly in deeply re-examining the findings from multiple perspectives.