**6. Chemopreventive stategies**

Inhibitors of 5-alpha reductase (5ARI), finasteride or dutasteride, may be used short term to decrease blood flow in the prostate before biopsy (as described at the end of section 3.4.4). Further, it is speculated their longer term use (6 months or more) may decrease proportion of benign prostate in a whole gland and in this way increase chances for prostate cancer detection on prostate biopsy. It may also reduce development of low grade cancer. One possible strategy for use of 5ARI inhibitors is prescription of drug after first or second negative biopsy and then regular follow up of PSA. PSA is expected to decrease. Trigger for repeat biopsy is any increase of PSA above nadir or if PSA value under 5ARI is above 40% of initial PSA value. Described approach was recently retrospectively evaluated in abstract form, using REDUCE data (Roobol et al., 2011). However, a proportion of prostate cancers do progress (for example on watchful waiting) without this fact reflecting in increase of PSA. Therefore a possibility of prostate cancer progression (in patients on 5ARI treatment or without) while PSA values would not increase is a serious concern and needs further research. We should always be aware, none of our methods is 100% successful.
