Plasma testosterone and prognosis of postmenopausal breast cancer patients

Purpose: High endogenous testosterone is associated with increased breast cancer (BC) risk. We designed this study specifically to assess the long-term prognostic role of testosterone in a cohort of postmenopausal BC patients. Patients and Methods: We considered 194 postmenopausal women, operated on for early BC (T1-2N0M0), who never received chemotherapy or hormonal therapy, and who participated in a fenretinide BC prevention trial as untreated controls. Blood samples were collected 3 months (median) after surgery; plasma samples, stored at -80°C, were radioimmunoassayed for testosterone. Median follow-up was 14 years. The main end point was any cancer event. Event-free survival was estimated by the Kaplan-Meier method. Hazard ratios (HRs) of events by testosterone level were estimated by the Cox model, adjusting for age, tumor size, and histology. Results: Patients with high testosterone (≥ 0.40 ng/mL, median of distribution) had significantly lower event-free survival than those with low testosterone (log-rank P = .004). The adjusted HR of patients with high versus low testosterone was 2.05 (95% CI, 1.28 to 3.27). High testosterone was also associated with a significantly higher risk of BC events (relapse and second primary) with an adjusted HR of 1.77 (95% CI, 1.06 to 2.96). Eleven second primaries (non-BC) occurred in the high-testosterone group, four in the low-testosterone group. Conclusion: High plasma testosterone strongly predicts poorer prognosis in postmenopausal BC patients not administered adjuvant therapy. Testosterone levels should be determined as part of the prognostic work-up.