Dr. Loeb“Our results from a population-based setting suggest against an increased risk of biochemical recurrence among men using PDE-5i after prostate cancer treatment,” said lead investigator Stacy Loeb, MD, MSc, at the Genitourinary Cancers Symposium in San Francisco. The findings were also published online in European Urology (Dec. 29, 2015).
No change in clinical practice regarding the use of PDE-5 inhibitors after prostate cancer treatment is therefore warranted, Dr. Loeb said.
The results corroborate recent findings from Italian investigators, who found no significant association between number of PDE-5 inhibitor pills taken and biochemical recurrence in 2,579 patients who underwent nerve-sparing radical prostatectomy (Eur Urol 2015; 68:750-3). An earlier study from the Martini-Clinic Prostate Cancer Center in Hamburg, Germany suggested a higher risk of prostate cancer recurrence using PDE-5 inhibitors (J Urol 2015; 193:479-83).
The German study “was a huge surprise to the urological community and caused concern given how commonly these medications are used,” said Dr. Loeb, assistant professor of urology and population health at New York University, New York. “Our study was meant to be the tie-breaker.”
Dr. Loeb’s group sought to settle the issue by using data from the National Prostate Cancer Register of Sweden linked to the National Prescribed Drug Register. They identified 293 men who had radiation therapy or radical prostatectomy and had biochemical recurrence after treatment. For each case, 20 controls were identified who were free of biochemical recurrence. One hundred fifty (51%) of the cases and 3,334 (58%) of the controls used oral PDE-5 inhibitor medication after treatment.
Biochemical recurrence was defined as two PSA measurements ≥0.2 ng/mL for men undergoing radical prostatectomy and two PSA measurements ≥2 ng/mL over the nadir for radiation therapy, with the date of the first such measurement considered the date of biochemical recurrence.
PDE-5 not linked to recurrence after RP, RT
The use of a PDE-5 inhibitor was not associated with biochemical recurrence either in the men who underwent radical prostatectomy (odds ratio [OR]: 0.78, 95% confidence interval [CI]: 0.59–1.03) or radiation therapy (OR: 0.98, 95% CI :0.49-1.97).
Higher PSA level and higher biopsy Gleason grade group were significant predictors of biochemical recurrence after prostatectomy and radiation therapy. Clinical stage T2 (compared with T1) and >33% positive biopsy cores were also significant predictors of biochemical recurrence after prostatectomy.
Dr. Loeb noted that a greater number of cumulative PDE-5 inhibitor pills after treatment was associated with a slightly lower risk of recurrence, a finding that lost significance after adjusting for pathologic features.
On stratification by exposure risk, there was no association between PDE-5 inhibitor exposure and risk of biochemical recurrence. Men whose cumulative number of PDE-5 inhibitor pills was above the median had a slightly lower risk of biochemical recurrence in the clinical model (OR: 0.68) and no difference in biochemical recurrence risk after adjustment for prostatectomy features (OR: 0.73).