arly salvage radiotherapy following radical prostatectomy indicated in patients with rising PSA levels below the conventional threshold of biochemical recurrence 0.2 ng/ml
Abstract
Aim: Prostate specific antigen (PSA) after radical prostatectomy (RP) assessed by ultrasensitive assay may help to detect biochemical recurrence (BR) at an early stage and thus probably more sensitive to salvage radiotherapy (SRT). We aimed to evaluate the efficacy of SRT in patients after RP with postoperative PSA increase below the levels 0.2 ng/ml and 0.2-0.3 ng/ml.
Methods: The prospective analysis comprised 52 patients who underwent SRT for rising PSA after RP for localized prostate cancer. Rising PSA was defined as three consecutive rises of PSA measured by an ultrasensitive PSA assay (Immuli-te 2000 3rd Generation PSA, Siemens Medical, detection limit 0.003 ng/ml).
Inclusion criteria were no history of hormonal therapy, postoperative PSA nadir lower than 0.1 ng/ml, indication for SRT with the PSA value lower than 0.2 ng/ml and a minimum follow-up after SRT 9 months. SRT was indicated in PSA levels below 0.2 ng/ml, in 11 patients SRT was started in PSA levels 0.2-0.3 ng/ml.
SRT was delivered to the prostatic bed (60 Gy) followed by boost at a total dose of 72-76 Gy. SRT failure was defined as three consecutive rises of PSA after SRT measured in 3 months' intervals.
Results: Median follow-up after SRT was 27 months (range 9-48 months). Mean follow-up after SRT was also 27 months.
SRT was in two of 52 patients (3.8%) practically without any effect. Long-term successful SRT lasting 27 months in average (9-48 months) was seen in 43 of 50 patients (86%).
Repeated PSA rise was seen in seven patients after temporary PSA decline lasting 15-27 months (median 15, mean 18 months). In three of them the rise exceeded the threshold of 0.2 mg/ml.
All these three patients had PSA level before the beginning of SRT above 0.2 ng/ml. The rate of SRT failure was higher in the group of SRT beginning in PSA levels 0.2-0.3 ng/ml (five of 11 patients, 45.5%) then in the group, where the SRT was started at PSA levels under 0.2 ng/ml (two of 39 patients, 5.1%, p < 0.01, Chi-square test).
Median and mean PSA level in the time of SRT beginning differed significantly between the group of SRT-failures (0.207 and 0.201 ng/ml) and the group of long-term successful SRT (0.133 and 0.134 ng/ml; p = 0.016, Mann-Whitney test). Conclusions: Results of this study indicate that early SRT in time when the patients' PSA elevation after RP did not reach the conventional threshold of biochemical recurrence yet, may lead to objective response in terms of long-lasting absence of PSA elevation.
More favorable outcomes were associated with PSA values under the value of 0.2 ng/ml at the time of SRT.