Differences in Treatment and Outcome after Treatment with Curative Intent in the Screening and Control Arms of the ERSPC Rotterdam

Screening for prostate cancer (PCa) results in a favorable stage shift. However, even if screening did not result in a clinically apparent lower stage or grade, it might still lead to less disease recurrence after treatment with curative intent (radical prostatectomy [RP] and radiation therapy [RT]) because the tumor had less time to develop outside the prostate. The outcome after treatment could also differ because of variations in treatment quality (eg, radiation dosage/adjuvant hormonal therapy). To test these hypotheses, we compared differences in the treatment quality of the screening and control arms of the European Randomized Study of Screening for Prostate Cancer (ERSPC) Rotterdam and disease-free survival (DFS) after curative treatment in PCa patients with similar stage and grade. A total of 2595 men were initially treated with RP or RT. In the control arm, RT was more often combined with hormonal therapy; treatment dosage was often ≥69 Gy. This most likely resulted from changes over time in treatment that coincided with the later detection in the control arm. DFS was higher in the screening arm in all risk groups. After correction for lead time, these differences were minimal, however. We concluded that treatment quality differed between the screening and control arms of the ERSPC Rotterdam. RT quality was especially superior in the control arm with higher dosages and more often RT in combination with hormonal therapy. Despite these differences favoring the control arm, DFS differences were minimal. Patient summary We looked at differences in prostate cancer (PCa) treatment and outcome after PCa treatment in men diagnosed after screening and men diagnosed after normal clinical practice. Treatment differed with superior treatment given to men diagnosed in normal clinical practice. We propose a likely explanation for this apparently counterintuitive finding (progressive insight combined with, on average, a later detection of tumors in unscreened men). Although unscreened men received better treatment, this advantage seemed to be outweighed by the advantage associated with the earlier detection, on average, of the tumor in screened men. Trial registration ISRCTN49127736

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