Radiotherapy for high grade clinically localized adenocarcinoma of the prostate

We defined the efficacy of radiotherapy for the treatment of high grade (Gleason scores 8 to 10) adenocarcinoma of the prostate.

A total of 50 patients underwent radiotherapy with curative intent for clinically localized prostate cancer with Gleason scores of 8 to 10 at 1 of 4 facilities affiliated with the University of California San Francisco. Patients were considered to have biochemical failure if they had a significant increase in prostate specific antigen (PSA) of 0.5 ng./ml. per year, an increase in PSA to greater than 1.0 ng./ml. or a positive biopsy.

Among the 50 patients median PSA was 22.7 ng./ml. (range 1.3 to 93.4). Tumors were clinical stage T1 or T2 in 46% of the cases and stage T3 or T4 in 54%. The overall actuarial probability of freedom from biochemical failure at 4 years was 23%. In a multivariate analysis including all patients pretreatment PSA was the only predictor of PSA failure, with 64% free of progression if the pretreatment PSA was 10 ng./ml. or less compared to only 16% at 3 years if PSA was more than 10 ng./ml. (p = 0.01). In a multivariate analysis restricted to patients with PSA less than 20 ng./ml. 83% of those treated to more than 71 Gy. were free of progression compared to 0% for those treated to less than 71 Gy. (p = 0.03). In a multivariate analysis PSA 10 ng./ml. or less (related risk 11.4, p = 0.02), T stage 1 or 2 (relative risk 3.8, p = 0.05) and radiation dose more than 71 Gy. (relative risk 4.0, p = 0.06) were associated with a favorable outcome.

At 4 years the freedom from PSA failure following radiotherapy for high grade prostate cancer was comparable to previously reported surgical series. The high failure rate among patients with PSA greater than 20 ng./ml. suggests that these patients should be considered for investigational approaches. The apparent improvement in freedom from progression with the use of higher doses provides reason for optimism.