Serum testosterone--a significant determinant of metastatic relapse for irradiated localized prostate cancer

To determine if the serum total testosterone concentration correlates with the outcome for men irradiated for clinically localized prostate cancer.

The outcome-local, nodal, distant metastatic, and biochemical--for 486 men with clinically localized prostate cancer treated by radiation and for whom testosterone levels were available was analyzed. No patient received adjuvant androgen ablation. Patient tumor stages were T1: 129 (27%); T2: 187 (38%); and T3/T4: 170 (35%). Median follow-up was 41 months.

Pretreatment testosterone values ranged from 109 to 1121 ng/dL, with a mean of 417 ng/dL and a median of 398 ng/dL. The distribution of patients according to a four-tier testosterone grouping was testosterone level of 300 ng/dL or less, 108 (22%); testosterone level greater than 300 ng/dL but not more than 400 ng/dL, 141 (29%); testosterone level greater than 400 ng/dL but not more than 500 ng/dL, 123 (25%); and testosterone level greater than 500 ng/dL, 114 (23%). There were statistically significant but trivial correlations between testosterone level and age, T-stage, and acid phosphatase level. There was no correlation between testosterone and prostate-specific antigen (PSA) levels. There was a highly significant correlation between testosterone level and metastatic relapse. Patients with testosterone level greater than 500 ng/dL had a markedly higher 6-year metastatic rate (16%) than those with a testosterone level of 500 ng/dL or less (4%) (P = 0.001). In multivariate analysis, testosterone level was an independent determinant of metastatic relapse, second only to PSA level and of about the same power as T-stage. Gleason grade, although significant, was less so than testosterone level. The correlation of testosterone level to outcome appeared to be specific for metastatic relapse having no relation to local outcome. Likewise, high testosterone levels were not associated with acceleration of postradiation serum PSA kinetics.

There is a highly significant correlation between pretreatment testosterone level and metastatic relapse in patients with clinically localized prostate cancer treated with radiation. As serum testosterone increases, so too does metastatic relapse. This relationship appears to take a decided turn for the worse at testosterone levels exceeding 500 ng/dL.