Screening for prostate cancer (PCa) remains controversial even if the European Randomized Study of Screening for Prostate Cancer (ERSPC) has shown a 21% relative reduction in PCa mortality. The Finnish Randomized Study of Screening for Prostate Cancer is the largest component of the ERSPC and showed statistically non-significant 16% mortality benefit in a separate analysis. The purpose of this study was to estimate the degree of contamination in the control arm (CA) of the Finnish trial.
Altogether 48,295 men were randomized to the CA and 31,872 men in the screening arm (SA). The screening period was 1996 - 2007. The extent of PSA testing was analyzed retrospectively using laboratory databases and incidence of T1c PCa (impalpable PCa detected by elevated PSA) was determined from the national Finnish Cancer Registry.
Approximately 1.4% of men had been tested with PSA 1-3 years before randomization. By the first four, eight and twelve years of follow-up, 18.1%, 47.7% and 62.7% of the men in the CA had been tested with PSA at least once, respectively. In the screening arm (SA), the corresponding proportions were 69.8%, 81.1% and 85.2%. The cumulative incidence of T1c PCa was 6.1% in the SA and 4.5% in the CA (RR 1.21; 95% CI 1.13-1.30).
A large proportion of the men in the CA had a PSA test during the 15-year follow-up. Contamination is likely to dilute differences in PCa mortality between trial arms in the Finnish screening trial.
The Journal of urology. 2017 Jan 16 [Epub ahead of print]
Tuomas P Kilpeläinen, Dimitri Pogodin-Hannolainen, Kimmo Kemppainen, Kirsi Talala, Jani Raitanen, Kimmo Taari, Paula Kujala, Teuvo L J Tammela, Anssi Auvinen
Dept. of Urology, University of Helsinki and Helsinki University Hospital, FI-00029 Helsinki, Finland. Electronic address: ., Dept. of Urology, Kanta-Häme Central Hospital, FI-13530 Hämeenlinna, Finland. Electronic address: ., School of Health Sciences, University of Tampere, FI-33014 Tampere, Finland. Electronic address: ., Finnish Cancer Registry, FI-00130 Helsinki, Finland. Electronic address: ., School of Health Sciences, University of Tampere, FI-33014 Tampere, Finland; UKK Institute for Health Promotion Research, FI-33501 Tampere, Finland. Electronic address: ., Dept. of Urology, University of Helsinki and Helsinki University Hospital, FI-00029 Helsinki, Finland. Electronic address: ., Fimlab Laboratories, Department of Pathology, Tampere University Hospital, FI-33521 Tampere, Finland. Electronic address: ., Dept. of Urology, University of Tampere and Tampere University Hospital, FI-33521 Tampere, Finland. Electronic address: ., School of Health Sciences, University of Tampere, FI-33014 Tampere, Finland. Electronic address: .