More prostate cancer screenings do not reduce aggressive disease

More prostate cancers were detected among men who were screened every 2 years than among men screened every 4 years, according to a study published in an online edition of the Journal of the National Cancer Institute (2007; 99:1296-303). But the shorter time between screenings did not reduce the number of aggressive cancers found between the scheduled screening tests.

Researchers in the Netherlands and Sweden conducted the study to determine whether the time between PSA screenings influenced the incidence of prostate cancer. They analyzed data collected at two European medical centers that participated in the European Randomized Study of Screening for Prostate Cancer.

At a center in Gothenburg, Sweden, 4,202 men were screened every 2 years, and in Rotterdam, the Netherlands, 13,301 men were screened every 4 years. The researchers compared both the number and characteristics of the interval prostate cancers diagnosed in these men. Serious, potentially life threatening interval cancers were analyzed separately.

Over a period of 10 years, the overall incidence of prostate cancer was higher among men screened every 2 years than among those screened every 4 years (13.14% vs. 8.41%). But the total number of interval cancers that were diagnosed between screening tests was 31 (0.74%) in Gothenburg and 57 (0.43%) in Rotterdam. This difference in the number of interval cancers and the number of aggressive interval cancers at the two centers was not statistically significant, indicating that the 2-year screening program did not reduce the number of interval cancers as would be expected.

“It is therefore more realistic to believe that each screening will again lead to prostate cancer diagnoses among some men from a large pool harboring small and often clinically insignificant disease and thus that more cancers were detected in Sweden because screening was more frequent,” wrote the authors, led by Monique J. Roobol, PhD, of Erasmus Medical Center, Rotterdam.