Patients with refractory prostate cancer previously treated with bicalutamide showed a decline in PSA levels following administration of flutamide: A report of two cases

We experienced 2 cases of refractory prostate cancer in patients previously treated with bicalutamide (BCL) where a decline in PSA levels was noted following the administration of flutamide (FLT). Case 1: A 61-year-old man was diagnosed with poorly differentiated prostate cancer (PC) with bone metastasis. Combined androgen blockade (CAB) comprising LH-RH analogue plus BCL was commenced. The level of PSA declined from 670 ng/ml to 1.92 ng/ml, but then gradually increased to 9.62 ng/ ml. We decided that the cancer was BCL-resistant and accordingly we stopped the administration of BCL. Because the PSA level continued to increase to 23.65 ng/ml 8 weeks after the cessation of BCL, FLT (250mg/day) was given. The level of PSA again declined to 7.75 ng/ml 9 weeks after the administration of FLT. However, re-elevation was detected 13 weeks later and 22 weeks later, the level of PSA was found to have increased to 17.07 ng/ml. Case 2: A 66-year-old man was diagnosed with poorly differentiated PC with bone and LN metastasis. Combined androgen blockade comprising LH-RH analogue plus BCL was commenced. The level of PSA showed a decline from over 100 ng/ml to 0.9 ng/ml 14 months later. However, after 3 consecutive elevations to 2.2 ng/ml, the administration of BCL was stopped. One month later, the PSA level had increased to 3.9 ng/ml, and so the administration of FLT (250mg/day) was started. After that, the PSA level declined to the nadir of 0.09 ng/ml, and 30 months later, the level is 0.23 ng/ml. Our experience suggests that FLT may be effective as a second-line therapy for refractory PC previously treated with BCL.