Treatment for prostate symptoms doesn't appear to increase risk for advanced prostate cancer

Treating prostate symptoms with 5α-reductase inhibitors (5-ARIs) does not appear to increase risk for advanced prostate cancer, a new study indicates.

In 2011, the FDA issued a safety announcement warning that 5-ARIs, which are used to treat prostate symptoms, might increase risk of more serious prostate cancer. The warning was based on two randomized, clinical trials finding that chemoprevention with 5-ARIs substantially reduced risk for prostate cancer at biopsy but also appeared to increase risk for more severe disease (i.e., a Gleason score of 8-10).

To determine the association between 5-ARI treatment for lower urinary tract symptoms related to prostate enlargement and risk for prostate cancer, especially more severe disease, researchers in Sweden performed a population-based case-control study of men who were diagnosed with prostate cancer in 2007-2009. Data on cancer diagnosis and 5-ARI use were obtained from several national databases. Risk for prostate cancer was the main outcome measure. The study results were published online by BMJ on June 18.

A total of 26,735 cases and 133,671 matched controls were selected for the study, with five controls randomly selected per case. The mean age was 69.3 years, and men who had disease with lower Gleason scores tended to be younger than those with higher scores. Overall, 7,815 men, 1,499 cases and 6,316 controls, had taken 5-ARIs, and 412 had done so before being diagnosed with higher-grade disease (Gleason score 8-10).

The researchers found that prostate cancer risk decreased as a whole with increased exposure to 5-ARIs (odds ratio [OR], 0.72; P<0.001 for trend in men treated for >3 years). Risk for cancer with Gleason scores of 2 to 6 and 7 also decreased with increased exposure (P<0.001 for trend in both comparisons). However, risk for disease with a Gleason score of 8 to 10 did not appear to change due to 5-ARI exposure (ORs, 0.96 for 0 to 1 year of exposure, 1.07 for 1 to 2 years of exposure, 0.96 for 2 to 3 years of exposure, and 1.23 for >3 years of exposure; P=0.46 for trend).

The researchers acknowledged that the study follow-up was relatively short and that data on prostate-specific antigen testing and digital rectal exam results at initiation of 5-ARI therapy were not available, among other limitations. However, they concluded that treatment with 5-ARIs decreased overall risk for prostate cancer and did not appear to be associated with increased risk for severe disease. “Our data, together with previous studies, suggest that the net balance between benefit and harm for 5-ARI use is favourable in men with lower urinary tract symptoms based on prostatic enlargement,” they wrote.