Power calculation: In the Västra Götaland healthcare region in 2012, 321 men had intermediate risk-level prostate cancer for which they received curative treatment. Calculation using the primary outcome (Ki-67) gives for a study group consisting of 118 patients an 80 % power for a two-sided test with a level of significance at 0,05 and effect size of 0,5. The investigators found in earlier studies that approximately 42 % of the male population are heterozygous or homozygous for the variant allele (TC/CC) of the ERβ promoter region SNP (rs2987983-13950 T/C) and 58 % homozygous for the wild type allele (TT). Since the investigators expect the effect of the intervention to be greater among subjects with the variant allele, while smaller among subjects with the wild type allele, this latter group ought to be large enough to be able to find a difference if one exists. Thus a total sample size of 118/58%=203 patients is needed.