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From the Winter 2019 Quest
More than meets the eye: common BPH and baldness drugs suppress PSA, which may conceal prostate cancer growth. ©Sanford Radom, M.D.
The last issue of QUEST reported on a study that found a troubling connection between BPH and baldness drugs and late diagnoses of prostate cancer. In September, the study's authors published a research letter looking at the same issues in a broader population in the U.S. The findings were consistent with the earlier study: patients who took the drugs had worse prostate cancer-related outcomes.

The medications scrutinized in the study are 5-⍺ reductase inhibitors (5-ARIs), hormone blocking drugs frequently prescribed to treat benign prostatic hyperplasia (BPH) and male pattern baldness. The generic names are finasteride and dutasteride; the trade names include Proscar, Propecia, and Avodart.

Misinterpreted PSA values

5-ARIs reduce PSA values by approximately 50%. If a patient taking 5- ARIs develops prostate cancer, the elevated PSA - which is often the first sign of prostate cancer - could be masked by the drug's effect on the PSA. Although algorithms exist to adjust the PSA value for a patient on 5-ARIs, doctors and patients may not be aware of the need to use them.

Without a correct understanding of the patient's PSA level, the doctor may not suspect cancer is present, the patient may not be referred for a biopsy, and this could lead to a late diagnosis of prostate cancer when the disease has already progressed to a later stage. At that point, it could be harder to treat and cure the cancer.

Data in a broader U.S. population

The team's newest report looked at more than 30,300 prostate cancer patients, about 8% of whom were taking 5-ARIs for at least six months before they were diagnosed with prostate cancer. The data came from a nationwide Medicare database. The earlier study looked at patient data from the U.S. Veterans Affairs database. The findings were similar between the two studies; men who took 5-ARIs had worse outcomes related to prostate cancer.

As with the earlier study, 5-ARI users were more likely to die from prostate cancer. Specifically, men who took 5- ARIs were 38% more likely to die from the disease, compared to men who did not take the drugs. Men in the 5-ARI group were also 15% more likely to die from any cause.

In addition, 5-ARI users were more likely to be diagnosed with high-grade prostate cancer with a Gleason score 8- 10. Twenty-nine percent of patients in the 5-ARI group had high-grade prostate cancer, compared to 18% in patients who did not take the drugs.

The adjusted PSA levels at diagnosis were much higher among 5-ARI users as well. At diagnosis, the 5-ARI group had a median PSA of 14.2, compared to 6.6 for patients who did not use 5-ARIs.

The authors concluded, "Our results suggest a need for increased awareness of 5-ARI-induced PSA suppression, clearer guidelines for early prostate cancer detection, and systems-based mechanisms to help improve care for men using 5-ARIs."

The research letter was published in JAMA Network Open.

 

Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a non-malignant enlargement of the prostate. It is a common condition in men aged 50 years and older. BPH can lead to problems with urination due to the prostate putting increased pressure on the urethra.

5-⍺ reductase inhibitors (5-ARIs reduce the size of the prostate, and thus the urinary problems get better. However, the drugs are controversial due to concerns over side effects.

5-ARIs are also prescribed for male pattern baldness.
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