Prostate-Specific Antigen Flare Phenomenon Induced by Abiraterone Acetate in Chemotherapy-Naive Patients With Metastatic Castration-Resistant Prostate Cancer.
Prostate-specific antigen (PSA) flare is a well-known phenomenon in patients with prostate cancer treated with luteinizing hormone-releasing hormone agonist and chemotherapy. However, its incidence and the significance for the clinical outcomes of patients treated with abiraterone acetate (AA) are uncertain.



A multicenter retrospective analysis of chemotherapy-naive patients treated with AA for metastatic castration-resistant prostate cancer (mCRPC) was conducted. The baseline characteristics, treatment history of mCRPC, and serum PSA kinetics during AA treatment were collected. The log-rank test was applied to compare progression-free survival (PFS) between patient groups with a PSA flare according to the different definitions and immediate PSA declines.



The data from 83 patients were analyzed. An immediate PSA decline of any amount was observed in 59 patients (71.1%). According to the various definitions of PSA flare, its incidence ranged from 6.0% to 10.8%. Although the median interval to the peak PSA level was 0.95 month, regardless of the PSA flare definition, the interval to the PSA nadir showed a wide range of 2.8 to 7.6 months. In PSA flare subgroup, the median PFS in patients with any PSA decline to less than the baseline and > 30% decline from the baseline was 12.4 months. The PFS duration of PSA flare patients did not significantly differ from that of patients with an immediate PSA decline of any amount and immediate > 30% decline without PSA flare.



The PSA flare phenomenon is not rare event during AA treatment. A PSA decline during AA treatment, with or without a PSA flare, was associated with favorable clinical outcomes. Thus, AA should not be withdrawn early in patients with mCRPC in whom an initial, isolated PSA increase has been observed.
Department of Breast and Medical Oncology, National Cancer Center Hospital East, Chiba, Japan.
Yujiro
Y
Ueda
Department of Breast and Medical Oncology, National Cancer Center Hospital East, Chiba, Japan. Electronic address: nmatsuba@east.ncc.go.jp.
Nobuaki
N
Matsubara
Department of Urology, Kitasato University School of Medicine, Kanagawa, Japan.
Ken-Ichi
KI
Tabata
Department of Urology, Kitasato University School of Medicine, Kanagawa, Japan.
Takefumi
T
Satoh
Department of Urology, Toho University Sakura Medical Center, Chiba, Japan.
Naoto
N
Kamiya
Department of Urology, Toho University Sakura Medical Center, Chiba, Japan.
Hiroyoshi
H
Suzuki
Department of Urology, Yokohama City University Graduate School of Medicine, Kanagawa, Japan.
Takashi
T
Kawahara
Department of Urology, Yokohama City University Graduate School of Medicine, Kanagawa, Japan.
Hiroji
H
Uemura
D000069501:Abiraterone Acetate / Q000008:administration & dosage* / Q000627:therapeutic use; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D018572:Disease-Free Survival; D006801:Humans; D007610:Kallikreins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy* / Q000378:metabolism; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
D000970:Antineoplastic Agents; C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen; D000069501:Abiraterone Acetate
Abiraterone acetate; PSA decline; PSA flare; Progression-free survival; mCRPC