Prostate Cancer Mortality In Screen And Clinically Detected Prostate Cancer: Estimating The Screening Benefit

Main Category: Prostate / Prostate Cancer
Also Included In: Preventive Medicine
Article Date: 31 Jan 2010 - 0:00 PDT

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UroToday.com - The European Randomized Study of Screening for Prostate Cancer (ERSPC) has demonstrated that screening has the potential for reducing mortality from prostate cancer (PC). In contrast, The Prostate, Lung, Colorectal and Ovarian (PLCO) trial showed no difference in PC mortality after comparing the number of men who died from PC in a screened population with that in a control population where screening was not recommended or performed on a systematic basis.

Despite the PLCO and ERSPC study designs that recommended no screening in the control population, opportunistic PSA testing occurred in 8-52% of men in the control populations. As a result, the outcome of both these studies will have been weakened by the considerable level of PC screening in the control populations, which may have resulted in an underestimation of the true benefits of PC screening.

One of the possible methods of estimating the true effect of PSA screening is the selection of a control population with a very low intensity of screening. In Northern Ireland (NI), PSA screening is not recommended and there is a well-documented low level of PSA testing (6% of men >50 years old). Further, men tended not to proceed to prostate biopsy until PSA levels were >10.0ng/ml, with few men with low PSA levels having a prostate biopsy. In the current study, we compared the characteristics and outcomes of a population participating in the ERSPC, section Rotterdam, with men in Northern Ireland (NI) during a time period when asymptomatic PSA screening was infrequent.

Between 1997 and 1999, a total of 11,970 men, aged 55-74 years, were included in the intervention arm of the European Randomized Study of Screening for Prostate Cancer (ERSPC) section Rotterdam. Control population consisted of 133,287 men, aged 55-74 years, between 1998 and 1999 in Northern Ireland (NI). Men were followed for PC incidence and PC-specific death until December 31, 2006.

In the intervention cohort, 11,970 men, median age 63 years, were included, with 1,153 (9.6%) of these diagnosed with PC during the follow-up period. In the control cohort 133,287 men were included, with 3,962 (3.0%) diagnosed with PC with identical follow-up. Median age at inclusion was similar. Age at diagnosis was higher in the control cohort (median 70 vs. 67 years, p<0.001) with a higher median PSA at diagnosis (18.0 vs. 5.1 ng/ml, p<0.001).

After a median follow-up of 8.5 years, the absolute rate of PC specific death was 0.36 per 1,000 person-years in the intervention cohort compared to 0.58 per 1,000 person-years in the control cohort. There was a significant reduction of 37% in PC-specific deaths during observation in the intervention population relative to the control population: RR 0.63 (95%CI, 0.45-0.88, p=0.008). The absolute risk difference was 1.8 PC specific deaths per 1000 men, which corresponds to 555 (1000/1.8) men that needed screening to save one man from PC specific death. Additionally, PC diagnosed by screening resulted in an increase in cumulative incidence with respect to the control population of 67 per 1000 men, which lead to 37 (555/1000*67) cases that had to be treated (NNT) in order to prevent one man from PC specific death.

Men undergoing systematic PSA screening had a 3.2 fold increased risk of being diagnosed with PC. After 8.5 years, the rate of PC deaths was 37% lower in the intervention population. In addition, 555 men needed to be screened and 37 men needed treatment to prevent one PC-specific death.

Written by Pim J. van Leeuwen, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations, etc., of their research by referencing the published abstract.

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