In the ASCO 2012 education session on "Controversies in Prostate Cancer: PSA Screening," Barnett Kramer from the National Cancer Institute's Division of Cancer Prevention began his talk by nothing that “it’s difficult to make healthy people better off than they are, so strong evidence of benefit is needed when putting large numbers of healthy people in harm’s way.”
The underlying cost debate surrounding the issue of whether or not to recommend prostate cancer screening is based on the idea that if you use healthcare resources in one area, they’re being diverted from another area by nature of there being a limited pool of funding. Kramer underlined the importance of looking at healthcare use and cost-effectiveness and the tradeoff between the two.
He went on to note that in the United States, “We have looked at these two questions as being the same: Does it work? and Should we do it?” He outlined the current criteria for implementing a screening program, which include the existence of an important health problem, a recognizable latent or early asymptomatic stage; a suitable test with agreed-upon cutoff values; an ability to preferentially detect lesions likely to progress; general agreement on who to treat; the existence of quality assurance standards, and affordability. According to Kramer, not even half of these criteria are currently met for prostate cancer.
About 3% of men in the United States die from prostate cancer, and Kramer noted that due to tools that were not available in 1973, over one million more men have since been diagnosed with prostate cancer. However, 13 years after the PLOC trial was started, (38,350 men were regularly screened with PSA and digital rectal exam), the study found that there was no benefit from screening in the control vs intervention arms. He did point out that there was contamination in the study because men in the control arm decided to be screened on their own during the study. A similar European study of 182,160 men had a slightly different conclusion in which they saw a slight benefit to screening.
Kramer ended by saying that “illusions of knowledge are the obstacles to discovery,” and cited the harms of screening: false positives, at least one biopsy with the adverse effects of hematospermia, hematuria, urinary retention, fever, and increasing rates of urosepsis with resistant organisms, and said “you’re curing a large number of men that didn’t need to be cured in the first place.” The positive benefits of screening in general include possible reduced risk of death from the target cancer, and reassurance, or peace of mind for men.
A final note the session attendees were left with was something Kramer had heard from a colleague with regard to screening for prostate cancer. “If you want to know what the chance is you have prostate cancer, take your age and put a percent sign next to it.”