No Elevated Breast Cancer Risk Seen in BPH Patients Treated with 5ARIs in Study

No Elevated Breast Cancer Risk Seen in BPH Patients Treated with 5ARIs in Study

Treating benign prostatic hyperplasia (BPH) with 5-alpha reductase inhibitors can increase breast size in men, a condition called gynecomastia, but they don’t raise a person’s risk of breast cancer, according to a study comparing these inhibitors to alpha-blockers.

The study, “Risk of gynecomastia and breast cancer associated with the use of 5-alpha reductase inhibitors for benign prostatic hyperplasia,” appeared in the journal Clinical Epidemiology.

Treatments for BPH, which causes an enlarged prostate gland, include α-blockers, which have been shown to improve maximal flow rate and patients’ quality of life, and inhibitors of the enzyme 5-alpha reductase (5ARIs), such as Propecia (finasteride) and Avodart (dutasteride), which have been shown to reduce total prostate volume and surgical risk in long-term follow-ups.

However, results obtained in previous clinical trials have suggested that men on 5ARIs may be more likely to develop gynecomastia and male breast cancer.

To investigate this association, researchers used the UK Clinical Practice Research Datalink to identify BPH patients (at least 40 years old) with no history of Klinefelter syndrome (one or more extra X chromosomes) or prostate, genital or urinary cancer, prostatectomy or orchiectomy (testicle removal surgery), gynecomastia or breast cancer, prior to treatment with 5ARIs or alpha-blockers.

The selected 94,701 men had been treated with 5ARIs (Propecia or Avodart, alone or in combination with alpha-blockers), alpha-blockers alone (alfuzosin, doxadosin, indoramin, prazosin, tamsulosin and terazosin), or neither treatment. Researchers then analyzed the incidence of gynecomastia or breast cancer among these men.

Results indicated that patients on 5ARIs (alone or in combination with alpha-blockers) were three times more likely to develop gynecomastia than those unexposed to these drugs, and those using alpha-blockers. But the patients faced no elevated risk of breast cancer.

Further analyses showed that the gynecomastia risk existed regardless of the number of prescriptions, exposure time, and presence or absence of other drug treatments known to be associated with gynecomastia.

Gynecomastia risk was also higher in men treated with Avodart than in those on Propecia.

“We observed a greater than three-fold elevation in risk of gynecomastia for users of 5ARIs (alone or in combination with ABs) in comparison to unexposed men, whereas there was no elevation of risk for men using ABs for the treatment of BPH,” the researchers concluded. “In contrast, our results suggest that the use of 5ARIs do not increase the risk of breast cancer in comparison to non-exposed men.”

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