ORLANDO, FL, USA (UroToday.com) - Dr. Bridget Koontz discussed two journal articles that made a significant impact in radiation oncology in today’s “Best of Journals Session.”
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The first was “The Impact of Adjuvant Radiotherapy on Survival of Patients with Node-Positive Prostate Cancer” by Abdollah and colleagues. The authors hypothesized that the effect of adjuvant radiation (aRT) depends on primary tumor features. This was a study of 1 100 patients who were pN1 status post prostatectomy and PLND. All patients received adjuvant hormone therapy (HT), while 35% received aRT within 90 days of surgery. Patients were retrospectively evaluated for clinical characteristics and use of aRT by regression-tree analysis and propensity score matching.
At baseline, the RT group had higher Gleason score, T stage, and rate of positive margins. When stratifying by number of nodes positive, the authors found that patients with more than 4 nodes had similar 8-year cause-specific mortality in both HT and aRT groups (28% vs 25%). Benefit was seen in the group who had 3-4 positive nodes: 8 year cause specific mortality was 21% in the HT group vs 3% in the aRT group (p=0.02).
Among patients with low volume nodal disease (1-2 nodes), Gleason score, T-stage, and margin status were important. There was no difference in mortality between the HT and aRT groups for Gleason scores 2-6. Evaluation of Gleason 7-10 patients with low-volume nodal disease also showed no difference between the groups for patients with T2 or T3a and negative margins (3% HT vs 4% aRT). However, among patients with low volume nodal disease, Gleason 7-10, and T3b, T4, or positive margins, 8-year cause0specific mortality was 16% in the HT group vs 7% in the aRT group (HR 0.30, p=0.002).
This study, although retrospective and with unbalanced cohorts, draws strength from its large size, multivariate analysis, and validation in external cohorts. Dr. Koontz highlighted the importance of this topic as a number of abstracts have been devoted to identification of the role of radiation in node positive, non-metastatic prostate cancer. Moreover, there is a phase III study in development on “Androgen Deprivation therapy with or without radiation therapy in patients with node-positive prostate cancer.”
The second paper presented was “The Natural History and Predictors of Outcome following Biochemical Relapse in the Dose Escalation Era for Prostate Cancer Patients undergoing Definitive External Beam Radiotherapy,” by Zumsteg and colleagues. This was a study of the natural history of biochemical failure (BF) following radiotherapy (EBRT), which has traditionally been poorly characterized. It included 609 men with biochemical failure after EBRT among a group of 2 700 patients treated between 1991 and 2008 at MSKCC. Patients received 75.6 to 86.4 Gy, and 55% received ADT. Data was retrospectively reviewed and multivariate analysis was performed to determine risk factors for distant progression at the time of BF. Risk factors that were identified include pretreatment Gleason Score, pretreatment T-stage, posttreatment doubling time < 3 months, and interval to biochemical failure < 3 years. Patients with two of these risk factors had a significantly higher incidence of distant mets (HR 5.67, CI 3.96-8.12) and PCSM (HR 4.18, CI 2.49-7.01) following BF than those with zero or one risk factor. Although this study was a retrospective single-institutional experience, it was one of the larger studies performed that used modern RT doses. This article was selected because it underscores the fact that patients who fail primary RT have very different outcomes. Given the heterogeneity of prostate cancer, it serves as a call for further study in “personalized medicine” through genomics and epigenetics to better identify patients who require earlier and/or more aggressive treatment.
Presented by Bridget F. Koontz, MD at the 2015 Genitourinary Cancers Symposium - "Integrating Biology Into Patient-Centric Care" - February 26 - 28, 2015 - Rosen Shingle Creek - Orlando, Florida USA
Duke University Health System, Durham, NC USA
Reported by Nikhil Waingankar, MD, medical writer for UroToday.com