SAN FRANCISCO—Extremely low levels of testosterone in men after they have undergone radical prostatectomy (RP) for intermediate- to high-risk prostate cancer are associated with an elevated risk for biochemical recurrence of the disease, researchers reported here at the annual Genitourinary Cancers Symposium.

In a retrospective study conducted at the University of Texas Health Science Center in San Antonio, Matthew W. Jackson, a fourth-year medical student, and colleagues examined the relationship between post-RP testosterone levels and biochemical failure in patients with Gleason 7-10 malignancy. 

The researchers stratified 462 patients into five groups based on their postoperative testosterone levels: 203 ng/dL or less (less than 10th percentile); 204-257 ng/dL (10th-25th); 258-410 ng/dL (25th-75th); 411-507 ng/dL (75th-90th); and 508 ng/dL or higher (greater than 90th). They defined biochemical failure as a postoperative PSA level greater than 0.2 ng/dL.

The five-year biochemical failure free survival (BFFS) rate was significantly worse among those in the less than 10th percentile of testosterone level than in those of all other groups. “I was surprised at first by that result, and I honestly expected quite the opposite,” said Jackson, who presented study findings.

The BFFS rate was 43.1% among men in the less than 10th percentile compared with 68.4%, 68.6%, 61.4%, and 61.8% among those in 10th-25th, 25th-75th, 75th-90th, and greater than 90th percentiles, respectively. The 10-year BFFS rates were 31.9%, 64.6%, 61%, 55.2%, and 41.2%. The five- and 10-year overall survival rates were similar among the groups.

The study cohort had a mean testosterone level of 345.2 ng/dL; 44 patients had levels of 203 ng/dL or less.

The symposium is co-sponsored by the American Society of Clinical Oncology, the American Society of Radiation Oncology, and the Society of Urologic Oncology.