Preoperative Serum Sex Hormone-Binding Globulin Level Is an Independent Predictor of Biochemical Outcome After Radical Prostatectomy

Abstract

To investigate the significance of preoperative serum sex hormone-binding globulin (SHBG) level regarding the postoperative biochemical outcome in patients who were followed up for relative longer periods after undergoing radical prostatectomy (RP). Preoperative serum levels of testosterone (T), free T, and SHBG level were prospectively analyzed in 307 consecutive patients who underwent RP at our institution between January 2006 and July 2007. We analyzed potential associations of sex hormones with postoperative biochemical recurrence (BCR)-free survival via multivariate Cox proportional regression analysis. Mean postoperative follow-up duration for 307 total patients was 72.1 ± 19.6 months. Kaplan-Meier curve demonstrated that BCR-free survival was significantly worse in patients with higher (≥ 40 ng/mL) SHBG level than others (P < 0.001). Serum T (P = 0.280) and free T (P = 0.606) levels showed no significant association with biochemical outcome. In multivariate analysis encompassing postoperative variables along with PSA, T, and free T, SHBG level (HR 1.825, 1.061-3.138; P = 0.030) was observed to be independently associated with BCR-free survival. Addition of SHBG level to the multivariate model for prediction of BCR-free survival resulted in increased accuracy (83.5% vs. 82.2%; P = 0.164). Our study of patients who were followed up for relative longer periods after RP shows that preoperative serum SHBG level, but not T, is an independent predictor of postoperative BCR-free survival. According to our findings, SHBG measurement may be useful in the selection of candidates for adjuvant treatment following RP.

FIGURE 1

Kaplan–Meier estimates of biochemical recurrence-free survival after radical prostatectomy in the low (<40 ng/mL) and high (≥40 ng/mL) preoperative serum SHBG groups among the total subjects. The biochemical recurrence-free survival rate was lower in high SHBG group (P < 0.001). SBHG = sex hormone-binding globulin.

FIGURE 2

Kaplan–Meier estimates of biochemical recurrence-free survival after radical prostatectomy in the low (<40 ng/mL) and high (≥40 ng/mL) preoperative serum SHBG groups among the 4 different subgroups: clinical stage ≤T1c (A), clinical stage ≥T2a (B), biopsy Gleason score ≤6 (C), and biopsy Gleason score ≥7 (D). SHBG = sex hormone-binding globulin.