Open Access

ARTICLE

PSA doubling time post radiation: the effect of neoadjuvant androgen ablation

S. Tyldesley¹, A. Coldman², T. Pickles¹

1 Department of Radiation Oncology, British Columbia Cancer Agency (BCCA), Vancouver, BC, Canada
2 Population and Preventive Oncology & Biostatistics, British Columbia Cancer Agency (BCCA), Vancouver, BC, Canada
Address correspondence to Dr. Scott Tyldesley, Dept. of Radiation Oncology, BC Cancer Agency, 600 West 10th Ave., Vancouver, BC V5Z 4E6 Canada

Canadian Journal of Urology 2004, 11(4), 2316-2321.

Abstract

Objective: To determine whether men who relapse after neoadjuvant androgen ablation (NAA) and high-dose radiation therapy (RT) have faster PSA doubling times (PSAdt) than those who are treated with RT alone.
Materials and methods: From a prospective database of 1880 patients treated with RT for localized prostate cancer, patients were selected for further study if they had a rising PSA profile >1 ng/ml, and were treated with either no NAA, or prolonged NAA (defined as 3-12 months NAA) with a minimum 5 years follow-up. The PSAdt was calculated from the exponential line of best fit from the first post-nadir value >1 ng/ml to the last PSA prior to secondary intervention. Those patients with a rising PSA profile at 5 years of follow-up were further examined with linear regression to determine factors of possible independent adverse effect.
Results: There were 251 patients eligible with rising PSA profiles. Patients treated with NAA had higher pre-treatment Gleason scores (p<0.001), PSA (p<0.001), and T stage (p<0.001). Median duration of NAA was 5.1 months. Rising PSA profiles occurred in 78% of the RT-only group and 70% of the NAA group. In regression analysis, factors predictive of more rapid PSAdt were pre-treatment Gleason score (p<0.001), pre-treatment PSA (p=0.025), and T stage (p=0.017). The use of NAA (p=0.4) was not significant.
Conclusion: The use of prolonged NAA in men treated with RT does not itself cause a more rapid PSAdt when relapse occurs. Faster relapse observed in these men is due to intrinsically more aggressive tumors prior to treatment.

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