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 10^th percentile); 204-257 ng/dL (10th-25^th); 258-410 ng/dL (25th-75^th); 411-507 ng/dL (75th-90^th); and 508 ng/dL or higher (greater than 90^th). 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 10^th 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 10^th percentile compared with 68.4%, 68.6%, 61.4%, and 61.8% among those in 10th-25^th, 25th-75^th, 75th-90th, and greater than 90^th 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.