From the Guidelines
Finasteride is used for the prevention of prostate cancer, as well as for the treatment of benign prostatic hyperplasia (BPH) and male pattern baldness.
Key Points
- The use of finasteride for prostate cancer chemoprevention has been shown to decrease the incidence of invasive cancers in healthy people 1.
- The Prostate Cancer Prevention Trial (PCPT) reported a decrease in cumulative incidence of prostate cancer from 24.4% in the placebo arm to 18.4% in the finasteride arm during the 7 years of the trial 1.
- However, an observed increase of Gleason scores 7 to 10 in the finasteride study arm compared with the placebo arm triggered concern about harm 1.
- The dose of finasteride currently being used to treat male pattern baldness is 1 mg per day, whereas the 5 mg per day used in the PCPT is used for BPH and prostate cancer chemoprevention 1.
- Men taking finasteride should be fully apprised of the remaining uncertainty surrounding high-grade cancers with finasteride, and the observed benefits must be weighed against theoretical harms in men who are being treated for symptomatic or bothersome conditions 1.
Benefits and Harms
- The benefits of finasteride for prostate cancer chemoprevention include a reduction in the risk of prostate cancer diagnosis, with a relative reduction in risk of approximately 26% 1.
- The harms of finasteride include the potential for an increase in high-grade prostate cancers, although this is still a topic of debate and ongoing research 1.
Future Directions
- Additional investigation is necessary to determine the effect of 5-ARIs on prostate cancer morbidity and mortality, and the results of ongoing trials such as REDUCE will aid in this assessment 1.
From the FDA Drug Label
The development and enlargement of the prostate gland is dependent on the potent androgen, 5α -dihydrotestosterone (DHT). Finasteride is a competitive and specific inhibitor of Type II 5α-reductase with which it slowly forms a stable enzyme complex. In patients with BPH, finasteride tablets have no effect on circulating levels of cortisol, prolactin, thyroid-stimulating hormone, or thyroxine.
The use of Finasteride is to inhibit the production of 5α-dihydrotestosterone (DHT), which is involved in the development and enlargement of the prostate gland. This is achieved by inhibiting the Type II 5α-reductase enzyme. The primary use of Finasteride is in the treatment of Benign Prostatic Hyperplasia (BPH) 2.
From the Research
Uses of Finasteride
- Finasteride is used to treat symptomatic benign prostatic hyperplasia (BPH) by reducing prostate gland enlargement and improving urinary flow and symptoms 3, 4, 5
- It is also used to treat androgenetic alopecia (male pattern hair loss) by inhibiting the conversion of testosterone to dihydrotestosterone (DHT) 6
- Finasteride has been investigated for its potential use in preventing prostate cancer and treating other DHT-mediated disorders such as acne, facial hirsutism, and frontal lobe alopecia 3, 4
Mechanism of Action
- Finasteride works by inhibiting the 5-alpha-reductase enzyme, which converts testosterone to DHT 3, 6, 4
- This inhibition reduces DHT levels in target organs such as the prostate and scalp hair, without affecting circulating levels of testosterone 3