Miami, FL—Although several studies have shown that the addition of androgen-deprivation therapy (ADT) to radiation improves disease-free survival (DFS) in men with intermediate-risk prostate cancer, this is a heterogeneous group of patients, and it is not clear whether they should all receive ADT plus radiation, or whether the benefit is confined to a specific subset of patients.
A nonrandomized retrospective study presented at the 2011 American Society for Radiation Oncology meeting suggests that the additive benefit of ADT in men with intermediate-risk prostate cancer treated with radiation is confined to those with a poor prognosis (Gleason score ≥4 + 3), whereas no such benefit is seen in those with a favorable prognosis.
“ADT was clearly of benefit in patients with Gleason scores of 4 + 3 and higher-volume disease. We need randomized trials to support these data, but in the interim, these findings may help clinicians identify a favorable subset of intermediate-risk patients who can be treated with radiation alone,” said Katherine Castle, MD, University of Texas M.D. Anderson Cancer Center, Houston.
Dr Castle recommended a personalized approach to management that considers tumor and patient characteristics in the decision of whether to use radiation alone or radiation plus short-course ADT.
The study included patients with intermediate-risk prostate cancer who received intensity-modulated radiation therapy or 3-dimensional conformal radiation between 1993 and 2008. A total of 327 patients received radiation alone (in doses ranging from 75.6 Gy to 78.0 Gy) and 218 received radiation plus up to 6 months of ADT.
Prognosis was categorized as favorable, unfavorable, or marginal according to the patient’s Gleason score, T-stage, and pretreatment prostate-specific antigen level. Patients with a favorable prognosis had either a Gleason score of 6 and stage T1b-T2b disease or a Gleason score of 3 + 4 and stage T1b-c disease. Those with marginal prognosis had a Gleason score of 3 + 4 and stage T2a-b disease, and those with an unfavorable prognosis had a Gleason score of 4 + 3 or stage T2c disease.
The biochemical DFS at 5 years was 94% for men with an unfavorable prognosis who received radiation plus ADT versus 74% with radiation alone (P = .005).
Patients with a favorable prognosis received no benefit from radiation plus ADT versus radiation alone; the DFS was 94% and 95%, respectively. In patients with a marginal prognosis, the DFS at 5 years was 91% for radiation alone and 100% for radiation plus ADT.