Radiation After Radical Prostatectomy Benefits Some Men With PSA Persistence

07/06/17

By Will Boggs MD

NEW YORK (Reuters Health) - Radiotherapy after radical prostatectomy for prostate cancer improves survival in some men with persistently elevated prostate-specific antigen (PSA), according to a multivariable predictive model.

As many as 20% of men with adverse pathologic characteristics fail to achieve an undetectable PSA after radical prostatectomy. Which of these men will benefit from postoperative radiotherapy remains unclear.

Dr. Alberto Briganti from IRCCS Ospedale San Raffaele and Vita-Salute San Raffaele University, Milan, Italy and colleagues sought to develop a predictive tool to identify men with PSA persistence at a higher risk of cancer-specific mortality (CSM) who might benefit from postoperative radiotherapy.

Their model, based on data from 496 patients from the Italian center and from the Mayo Clinic in Rochester, New York, included pathologic grade group, pathologic stage, nodal status, surgical margins, and immediate androgen-deprivation therapy.

This model had a discrimination accuracy for predicting 10-year CSM risk of 67%, according to the June 13th European Urology online report.

The association between CSM-free survival and PSA at 6-8 weeks after surgery differed according to baseline CSM risk, such that the negative impact of increasing PSA was evident only among men with a CSM risk of 10% or higher.

Postoperative radiotherapy benefited only those men whose predicted risk of CSM was at least 30%.

“Increasing PSA levels should be considered as predictors of mortality, exclusively in men with a risk of CSM of >10% defined by pathologic characteristics,” the researchers conclude. “Likewise, the benefits of postoperative RT on survival are restricted to those men with adverse pathology, indicating the opportunity for an individualized approach to treatment in these patients.”

Dr. Daniel E. Spratt, chair of the Genitourinary Division for Clinical Research, University of Michigan, Ann Arbor, told Reuters Health by email, “Patients with a persistently positive PSA after surgery have significantly worse outcomes compared to those who do not, and this study further demonstrated that the absolute PSA level dramatically impacts survival rates.”

“Given the limited number of deaths in this study, model based calculations, and no information of development of metastasis or recurrence, it is challenging to use their identified cut-points for the use of postoperative radiotherapy,” he said. “The study is hypothesis generating in that there may be patients even with a persistently positive PSA where postoperative radiotherapy is not going to help the patient live longer; however, these patients remain to be precisely defined.”

“Use of molecular imaging and genomic biomarkers may prove to be more useful in this setting than just risk of death to select who needs postoperative RT,” Dr. Spratt said.

“Although having a persistently elevated PSA is a negative prognostic factor, many men will still have a very low rate of dying of prostate cancer in the next 10 years and should be counseled appropriately,” he said. “However, patients with aggressive clinical and pathologic features who have a persistently positive PSA >0.4 ng/mL have a relatively high risk of prostate cancer-related death and likely need further treatment.”

Dr. Spratt added, “There is an open national clinical trial for men with persistently positive PSA, NRG GU-002, which is intensifying systemic therapy with chemotherapy to help these men. (http://bit.ly/2uv5aIW)”

Dr. Briganti did not respond to a request for comments.

SOURCE: http://bit.ly/2uuTA0p

Eur Urol 2017.

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