Avodart & Proscar for Treating Prostate Cancer

Is it safe to use for men with prostate cancer?

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Avodart and Proscar are FDA-approved for treating urinary side effects from prostate enlargement.  The generic name for Avodart is dutasteride; the generic name for Proscar is finasteride. These medications, however, have a wider potential spectrum of action than simply enhancing urinary function. They work by blocking a type of testosterone called dihydrotestosterone (DHT) that concentrates in the prostate, stimulating it to grow and produce semen.

When DHT is blocked the prostate gland shrinks, improving urinary flow.

There are potential side effects. Semen production is usually reduced. Occasionally men report a reduction in libido and potency. Also, breast enlargement can occur. Generally, these side effects will wear off or reduce as long as the medication is stopped at the first sign of a problem.  Apart from the urinary benefits, there is a rather long list of other potential benefits.

Avodart or Proscar can:

  1. Lower PSA and reduce the risk of being diagnosed with prostate cancer
  2. Improve the detection rate of high-grade prostate cancer in men undergoing a biopsy
  3. Cause Gleason 6 cancer (low-grade cancer) to regress or be suppressed
  4. Synergize with other medications used to treat prostate cancer such as Casodex or Lupron
  5. Help maintain men on active surveillance and lower the risk of needing surgery or radiation
  6. Reduce male pattern baldness
  1. Delay orgasm in men with premature ejaculation

Anti-Cancer Effects

In a randomized study comparing Proscar with placebo, 10,000 men underwent a prostate biopsy after seven years of treatment. The Proscar-treated men were diagnosed with cancer 25% less frequently compared to the men treated with a placebo.

  However, enthusiasm for the routine use of Proscar to prevent cancer was dampened because the same study reported a 1% increased incidence of diagnosing high-grade prostate cancer. Experts at that time hypothesized that Proscar was increasing the detection rate rather than causing high-grade disease. However, Peter Scardino MD, a prominent urologist from Memorial Sloan Kettering published an opinion that Proscar could be causing high-risk cancer, raising all kinds of consternation and inciting the FDA to place a warning. All these fears were finally dispelled in the August 15th 2013 issue of the New England Journal of Medicine that showed no increased prostate cancer mortality in the men who were treated with Proscar compared to the men treated with placebo after 18 years of observation.

Since Avodart and Proscar work by a similar mechanism, much of what is known about Proscar can also be said about Avodart. Both agents block 5- alpha reductase (5-AR), an enzyme that converts testosterone into DHT.

  There is a theoretical advantage of Avodart over Proscar because Avodart blocks 5-AR enzyme somewhat more thoroughly.  No clinical trials, however, have been performed to compare these two agents head to head.

Since both Proscar and Avodart lower PSA by about 50%, the question arises, “Are they masking the capacity of PSA to signal cancer progression?”  Briefly, the answer is no. These medications do not stop the PSA from rising in men with progressive cancer. However, the PSA does reset at a 50% lower level after starting Proscar or Avodart. On average, a man with a PSA of 6.0 before starting Proscar will drop to 3.0 within a few months. Subsequently, if the PSA rises consistently above 3.0, cancer progression needs to be entertained as a possible cause.

Proscar and Avodart tend to have mild side effects and there are few if any interactions with other medications. When side effects occur, they tend to be reversible.  Proscar and Avodart are convenient because they can be taken any time of the day, with or without food. Finasteride, generic for Proscar is available and very affordable. This favorable cost and side effect profile makes it an ancillary consideration for patients with prostate cancer who want to control their PSA while still maintaining a good quality of life with low cost. 

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