Prostate drugs warning issued in Canada
The prescription drugs finasteride, used to treat an enlarged prostate and male pattern baldness, and dutasteride, also to help men with the prostate condition, may increase the risk of high-grade prostate cancer, Health Canada warns.
The warning, issued Monday, comes following reviews of two international trials. However, it notes that high-grade prostate cancer, which grows and spreads more quickly than low-grade prostate cancer, is rare, and the increased risk of using the two drugs is still considered very small.
As a result of the assessment of the trials, new safety warnings have been added to the Canadian drug labels for finasteride and dutasteride products. Updates to labels for the generic forms of the two drugs are also coming.
Some facts about prostate cancer:
- The most common cancer of men, one in seven in Canada will be diagnosed with the disease, and 4,100 die annually.
- Over 90 per cent of prostate cancer cases are curable if detected and treated early.
- Develops as a result of dietary, environmental and hereditary factors, but more research is needed to identify causes.
- No symptoms in earliest, most curable stage. Men 40 and over should talk to their doctors about a prostate exam (digital rectal exam and prostate specific antigen blood test).
- In some patients, close monitoring may be sufficient treatment. Others, with more aggressive disease, may need surgery or radiation, sometimes with hormonal therapy.
Source: Prostate Cancer Canada
Following are more details of the drugs:
- Finasteride is available under the brand names Proscar (5 mg finasteride) and Propecia (1 mg finasteride), and their generic equivalents.
- Dutasteride is available under the brand names Avodart and Jalyn (a combination drug product containing dutasteride and tamsulosin).
- Proscar, Avodart and Jalyn treat benign prostatic hyperplasia (BPH), or an enlarged prostate, a common condition in men over 40. Propecia is used to treat male pattern hair loss.
Health Canada says its review of the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial — which both sought to assess whether the two drugs were effective in preventing prostate cancer — found men 50 and over who used 5 mg of finasteride and dutasteride over four years had a "small but statistically significant increased risk of high-grade prostate cancer."
The federal department noted that the 1 mg finasteride strength (Propecia) was not included in these trials, "but a potential risk has not been ruled out."
Finasteride and dustasteride are not approved for the prevention of prostate cancer in Canada.
Health Canada says health-care practitioners should evaluate patients thoroughly to rule out urological diseases, including prostate cancer given that symptoms for cancer and BPH are similar, before prescribing Proscar, Avodart and Jalyn.
Patients with questions or concerns about their treatment with finasteride or dutasteride should talk to their doctors, and not stop taking their medications unless they have been medically advised to do so.