Limited suppression of prostate-specific antigen after salvage radiotherapy for its isolated elevation after radical...

To investigate the clinical outcome and degree of prostate-specific antigen (PSA) suppression after salvage radiotherapy performed because of isolated PSA elevation after radical prostatectomy.

We examined the outcomes of 32 patients who underwent radiotherapy after radical prostatectomy. Hypersensitive, as well as conventional, PSA assays were used to measure PSA levels after irradiation.

Of 125 patients who underwent radical prostatectomy for clinically resectable prostate cancer, 42 (33.6%) developed detectable PSA an average of 13.5 months postoperatively. Thirty-two patients underwent salvage radiotherapy. In 13 patients (40.6%), PSA became undetectable (less than 0.1 ng/mL) at a mean of 1.2 months. Two of these patients later developed detectable PSA within 1 2 months. Of 22 patients who had at least 12 months of follow-up, 8 had a durable PSA response. Of 13 patients who attained an undetectable PSA postoperatively and then showed a delayed progressive increase, 7 exhibited a durable response lasting for more than the 12 months after irradiation. By contrast, only 1 of 9 patients with persistently elevated postoperative PSA showed undetectable levels after irradiation. Frozen sera from the 8 patients with a durable response to irradiation were available to measure levels less than 0.1 ng/mL by hypersensitive assay. The mean value was 0.035 ng/mL at an average of 26.9 months after irradiation. Only 3 patients had levels less than 0.01 ng/mL.

Although radiotherapy may be beneficial in a small number of patients, many patients continue to have measurable levels of PSA (more than 0.01 ng/mL) after irradiation. Our results suggest that this treatment in its current form is inadequate to eradicate residual carcinoma.