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Can combined androgen blockade provide long-term control or possible cure of localized prostate cancer?
Fernand Labrie1, Bernard Candas, Jose-Luis Gomez
1Prostate Cancer Clinical Research Unit, Department of Medicine, Laval University Medical Center (CHUL) and Laval University, Quebec City, Quebec, Canada.
Objectives:
To investigate the possibility that more complete blockade of androgens or combined androgen blockade (CAB) could lead to even longer term control of localized prostate cancer. A series of recent studies have shown important benefits on survival using medical or surgical castration in localized or locally advanced prostate cancer.
Methods:
The effect of CAB on long-term control or possible cure of prostate cancer was evaluated by the absence of biochemical failure or prostate-specific antigen (PSA) rise for at least 5 years after cessation of continuous treatment. A total of 57 patients with localized or locally advanced disease received CAB for periods ranging from 1 to 11 years. Twenty patients with Stage B2/T2 prostate cancer who were treated for a median duration of 7.2 years (range 2.8 to 11.7) with CAB stopped treatment and were followed up for a median of 4.9 years. Eleven patients with Stage B2/T2 also received CAB but for only 1 year. Twenty-six patients with Stage C/T3 treated with continuous CAB for a median of 9.9 years (range 3.8 to 11.3) with undetectable PSA levels stopped treatment and were followed up for a median of 5.6 years. The median follow-up since diagnosis was 14.6 years for patients with Stage B2/T2 and 16.4 years for patients with Stage C/T3 disease.
Results:
With a minimum of 5 years of follow-up after cessation of long-term CAB, two PSA rises occurred among 20 patients with Stage T2-T3 cancer who stopped treatment after continuous CAB for more than 6.5 years, for a nonfailure rate of 90%. For the 11 patients who had received CAB for 3.5 to 6.5 years, the nonfailure rate was only 36%. The serum PSA increased within 1 year in all 11 patients with Stage B2/T2 treated with CAB for only 1 year, thus indicating that active cancer remained present after short-term androgen blockade despite undetectable PSA levels. In all patients who had biochemical failure after stopping CAB, the serum PSA level rapidly decreased again to undetectable levels when CAB was restarted and remained at such low levels afterward. Of these patients, only 1 patient had died of prostate cancer at last follow-up.
Conclusions:
The present data suggest that long-term and continuous CAB offers the possibility of long-term control or possible cure of localized prostate cancer.