Roobol MJ et al. (2007) Interval cancers in prostate cancer screening: comparing 2- and 4-year screening intervals in the European Randomized Study of Screening for Prostate Cancer, Gothenburg and Rotterdam. J Natl Cancer Inst 99: 1296–1303

The introduction of PSA screening for prostate cancer has resulted in an increased incidence of this disease; however, the optimum screening interval has yet to be determined. Roobol and colleagues compared the rate of interval cancers (cancers diagnosed during the interval between screenings) in Rotterdam, The Netherlands (4-year screening interval) and Gothenburg, Sweden (2-year screening interval).

Data of men aged 55–65 years at the time of their first screening were obtained from the screening arms of the Rotterdam (n = 13,301) and Gothenburg (n = 4,202) centers of the European Randomized Study of Screening for Prostate Cancer (ERSPC). All interval cancers and aggressive interval cancers (defined as any one of the following features: stage M1 or N1, plasma PSA concentration >20 ng/ml or Gleason score >7) were recorded via linkage with national cancer registries.

Over the 10-year screening period, the overall cumulative incidence of prostate cancer at the 4-year screening interval center (Rotterdam) and the 2-year interval center (Gothenburg) was 1,118 (8.41%) and 552 (13.14%), respectively (P <0.001). The incidence of interval cancers at the Rotterdam and Gothenburg centers was 57 (0.43%) and 31 (0.74%), respectively (P = 0.51), and the incidence of aggressive prostate cancer was 15 (0.11%) and 5 (0.12%), respectively (P = 0.72).

The authors conclude that, although the 2-year screening interval showed a higher detection rate than the 4-year screening interval, there were no significant differences in the rates of either interval or aggressive interval prostate cancer.