Two major trials have been performed to determine the effect of 5α-reductase inhibitors on subsequent diagnoses of prostate cancer. Both trials showed that high alcohol intake significantly increased prostate cancer risk among men allocated to the treatment arms. The recommendation that patients eliminate alcohol when taking 5α-reductase inhibitors seems appropriate.
Gomella, Leonard G, "Prostate cancer: alcohol, cancer and 5α-reductase inhibitors-is there a link?" (2014). Department of Urology Faculty Papers. Paper 32.