Detectable PSA after RP warrants aggressive radiation

February 17, 2015

Earlier, more aggressive radiation therapy is recommended in prostate cancer patients with detectable PSA following radical prostatectomy, say the authors of a recently published study.

Earlier, more aggressive radiation therapy is recommended in prostate cancer patients with detectable PSA following radical prostatectomy, say the authors of a recently published study.

The study is a 10-year post-treatment analysis of the German ARO 96-02 trial, a prospective clinical trial that compared observation to an adjuvant radiation therapy approach in patients with node-negative prostate cancer who underwent prostatectomy. It appears in the International Journal of Radiation Oncology • Biology • Physics (2015; 91:288–94).

ARO 96-02 accrued 388 patients from 1997 to 2004 with pT3-4pN0 prostate cancer with positive or negative margins who had already undergone radical prostatectomy. A total of 22 centers in Germany participated in the trial. Three patients were excluded from the study because they received immediate hormonal treatment.

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Prior to reaching an undetectable PSA post-prostatectomy, 159 patients were randomized to a wait-and-see approach (Arm A) and 148 patients were randomized to receive adjuvant radiation therapy (Arm B). Seventy-eight patients who did not achieve an undetectable PSA were moved to Arm C. Four of the patients in Arm C refused treatment, and 74 were treated with salvage radiation therapy in Arm C.

All patients in the study had a preoperative and postoperative PSA test, a bone scan, and chest radiography. Patients in Arm B received 60 Gy of 3-D conformal radiation therapy. Patients in Arm C received 66 Gy of 3-D conformal radiation therapy. Follow-up was conducted for all eligible patients in the trial quarterly for the first 2 years, twice a year from 3 to 6 years after treatment, and annually thereafter. The median follow-up was 112 months (9.3 years).

Of the 74 patients in Arm C, 58% also underwent hormone therapy as a result of recurrence (at the discretion of the attending physician). Seven patients in Arm C, of the 48 who had data available, reached an undetectable PSA after completion of salvage radiation therapy. In Arms A and B, 20 patients (7%) experienced distant metastasis, and in Arm C, 16% of patients experienced distant metastasis, according to a news release from the American Society for Radiation Oncology.

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Patients with detectable PSA after surgery (Arm C) experienced limited side effects as a result of radiation therapy, the researchers reported. Patients in Arm C did not report any grade 3 or grade 4 acute toxicities. Seven patients experienced severe late effects, with five patients reporting grade 3 bladder impairment, and two patients reporting grade 2 bladder impairment. Fifty patients (68%) in Arm C did not report any genitourinary late toxicity, and 59 patients (80%) in Arm C did not report any gastrointestinal late toxicity.

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Clinical relapse-free survival was calculated using the Kaplan-Meier method. In Arm C, patients had a 10-year clinical relapse-free survival rate of 63%. Univariate analysis demonstrated that patients in Arm C who had a Gleason score <8 (p=.0023), pT <3b (p=.0076), or an extraprostatic tumor extension <2 mm (p=.0047) had a better relapse-free survival rate. 

Using the Kaplan-Meier method to determine overall survival, patients in Arm A had a 10-year overall survival rate of 86%, and patients in Arm B had a 10-year overall survival rate of 83%. By comparison, those in Arm C had a 10-year overall survival of 68%.

“After patients undergo radical prostatectomy, the marker for PSA should fall below detection limits. Our analysis demonstrates that patients who have detectable PSA post-prostatectomy may benefit from more aggressive, early, and uniform treatment that could improve survival outcomes,” said lead study author Thomas Wiegel, MD, of University Hospital Ulm in Ulm, Germany.

“The impact of PSA persistence on 10-year overall survival is evident based on this new analysis. Improved imaging or surrogate markers beyond PSA are desirable to distinguish risk groups among men with PSA persistence. Larger, prospectively randomized clinical trials should examine additional treatment options to come to a standardized therapy for prostate cancer patients with PSA persistence.”

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