Prognostic Significance of Rising Prostate-Specific Antigen (PSA) Levels Following Radiation Therapy for Localized Prostate Cancer—Comparison Between PSA Bounce Versus PSA Recurrence

Abstract

In addition to the cure rate, quality of life is now very important in cancer therapy. For prostate cancer patients, urinary and intestinal symptoms after radiation therapy including intensity-modulated radiation therapy and proton therapy (PT) have been discussed. However, testosterone levels and sexual function after PT have not been well studied. This is a prospective evaluation of serum testosterone level and sexual function before and after PT. Materials/Methods: Between February 2013 and July 2014, 198 patients were treated with proton therapy. Among them, 171 patients consented to testosterone measurement, provided a sufficient response to a questionnaire, and received treatment exactly per protocol; they were fully evaluable for this study. There were 36 low-risk patients, 60 intermediate-risk patients and 75 high-risk patients, according to the National Comprehensive Cancer Network. For low-risk patients, 74 GyE/37 Fr was delivered without combined androgen blockade therapy (CAB). Intermediate-risk patients received 78 GyE/39 Fr after neo-adjuvant CAB for 6-8 months. High-risk patients received 78 GyE/39 Fr after neo-adjuvant CAB. They were basically treated with CAB for more than 1 year after PT. The serum testosterone, IIEF-5 (International Index of Erectile Function-5) and EHS (Erection Hardness Score) were evaluated before and after PT. Results: In low-risk patients, the average serum testosterone level was 428 (ng/dl) before PT, 450 at 3 months after PT (P Z 0.21), 442 at 6 months (P Z 0.46), 439 at 9 months (P Z 0.6), and 444 at 12 months (P Z 0.47). The median IIEF-5 score was 14 before PT and at 1 and 6 months, and 12 at 12 months (P < 0.001). The median EHS was 2 before PT and at 1 and 6 months, and 1 at 12 months (P Z 0.003). In intermediate-risk patients, the average serum testosterone was 8.2 (ng/dl) before PT, 145 at 3 months (P < 0.001), 244 at 6 months (P < 0.001), 295 at 9 months (P < 0.001), and 335 at 12 months (P < 0.001). The median IIEF-5 score did not change from 9 before and after PT. The median EHS score was 0 before PT and at 1 month, and 1 at 6 (P Z 0.01) and 12 months (P Z 0.006). In high-risk patients, the average serum testosterone was 6.6 (ng/dl) before PT, 21.2 at 3 months (P Z 0.13), 28.4 at 6 months (P Z 0.07), 41.1 at 9 months (P Z 0.02), 42.2 at 12 months (P Z 0.04), 82.3 at 15 months (P Z 0.004), and 98.8 at 18 months (P Z 0.002). The median IIEF-5 score and EHS did not change from 9 and 0, respectively. Conclusion: Without CAB, PT did not decrease the serum testosterone level and had a smaller influence on sexual function. The serum testosterone returned quickly to the normal level after the treatment in intermediate-risk patients, but sexual quality did not improve remarkably. In high-risk patients, the testosterone was suppressed and sexual function did not change in worse scores while they were treated with CAB. Combination of CAB and PT seems to have a greater influence on sexual function.