Prostate Cancer Screening and Surveillance

To the Editor: In their Clinical Crossroads article, Drs Sanda and Kaplan¹ reviewed prostate cancer treatment. I am concerned about some of their statements regarding the findings of the European Randomized Study of Screening for Prostate Cancer (ERSPC).² First, they described the reduction in prostate cancer mortality by noting 326 deaths among controls vs 214 in the screened group. However, this was misleading because it did not indicate that the control group had 89 435 participants while the screened group had only 72 952. Although there was, nonetheless, a real benefit (with a rate ratio of 0.80 at 9 years), the absolute risk reduction was only 0.71 per 1000 men, which I believe gives a different but more accurate impression.

Second, the authors did acknowledge the number-needed-to-screen of 1410 and correctly note that this is similar to screening benefit ratios for breast and colon cancer. However, they did not consider the more salient data on the additional number-needed-to-treat to prevent 1 prostate cancer death, which was 48. This is a reflection of the relative inefficiency of prostate-specific antigen (PSA) testing compared with screens for other cancers, with consequent overdiagnosis and overtreatment. In the European trial, for every 1000 men aged 55 to 69 years in the PSA screening group, 82 cancers were diagnosed (and presumably treated).² In a modeling study, among women aged 60 years undergoing 5 biennial mammographic screens, the rate of breast cancer diagnosis over 10 years was 38 per 1000 and the reduction in breast cancer mortality was 3.0 per 1000.³ Thus, in this comparison, men are more than twice as likely to be given the diagnosis of prostate cancer for less than one-fourth the benefit.

Third, the authors stated that “most prostate cancer mortality (in the absence of treatment) occurs 10 to 20 years after diagnosis,” and therefore longer follow-up should provide “more meaningful indications” of benefit. However, morbidity that occurs with prostate cancer treatment (including pain, fear, cost, and lingering disability) begins immediately. Given that these benefits are speculative and delayed 10 to 20 years in mostly older men, this prediction clearly requires a discounted analysis.

In addition, the authors were critical of the negative results and future prospects of the US Prostate, Lung, Colon, and Ovarian Cancer Screening Trial (PLCO)⁴ because of “overwhelming contamination” of PSA screening in the control group. This contamination is a consequence of advocacy of PSA screening by many physicians in the absence of adequate evidence of benefit.