Abstract
INTRODUCTION: Transient decrease in serum prostate-specific antigen level can occur after abiraterone acetate withdrawal in male patient with metastatic castration-resistant prostate cancer. Here, we report a case of abiraterone acetate withdrawal syndrome with transient prostate-specific antigen decrease after progression to castration-resistant disease while using upfront abiraterone therapy for high-risk prostate cancer. CASE PRESENTATION: A 73-year-old man with hormone-sensitive high-risk prostate cancer with multiple bone metastases (prostate-specific antigen level, 294.109 ng/mL) received upfront abiraterone/prednisolone combination and androgen deprivation therapy. One year later, prostate-specific antigen level decreased to 0.017 ng/mL (nadir) but it gradually rose by 15 months after treatment initiation. He was diagnosed as castration-resistant and new bone metastases appeared. After abiraterone was discontinued, prostate-specific antigen level decreased and stabilized at a low level for 5 months. CONCLUSION: Abiraterone acetate withdrawal syndrome was observed when hormone-sensitive prostate cancer with upfront abiraterone therapy progressed to castration-resistant prostate cancer.