Long-Term Results of a Randomized Trial Comparing Iridium Implant Plus External Beam Radiation Therapy With External Beam Radiation Therapy Alone in Node-Negative Locally Advanced Cancer of the Prostate

To determine the impact on long-term survival from the addition of brachytherapy to external beam radiation therapy (EBRT) in patients with prostate cancer.

Between 1992 and 1997, 104 men with cT2-3, surgically staged node-negative prostate cancer were randomized to receive either EBRT (40 Gy/20 fractions) with iridium implant (35 Gy/48 hours) or EBRT alone (66 Gy/33 fractions) to the prostate.

According to T stage, Gleason score, and prostate-specific antigen level, 60% of patients had high-risk disease. Substantial improvements in biochemical control at 8 years have previously been reported. Additional follow-up was collected on deaths and metastases.

Median follow-up was 14 years. Five patients were lost to follow-up. All other patients have been followed a minimum of 13 years. There have been 75 deaths, including 21 from prostate cancer and 25 from second cancers. No patients developing a second cancer have died from prostate cancer. There was no difference in overall survival between the 2 treatment groups: 34 deaths (67%) in the implant arm and 41 (77%) in the EBRT arm (hazard ratio [HR] 1.00, 95% confidence interval [CI] 0.63-1.59). Similarly, there was no difference in prostate cancer-specific deaths: 9 (18%) patients in the implant arm compared with 12 (23%) in the EBRT arm (HR 0.79, 95% CI 0.34-1.87). There was no statistically significant difference in the number of patients developing metastatic disease: 10 (20%) in the implant arm and 15 (28%) in the EBRT arm (HR 0.70, 95% CI 0.32-1.57). Improvements in biochemical control were maintained (HR 0.53, 95% CI 0.31-0.88).

Despite a dramatic reduction of biochemical recurrence rates, the addition of iridium implant to EBRT did not translate into improved overall survival or prostate cancer-specific survival.

International journal of radiation oncology, biology, physics. 2017 May 17 [Epub]

Ian S Dayes, Sameer Parpia, Jaclyn Gilbert, Jim A Julian, Ian R Davis, Mark N Levine, Jinka Sathya

Department of Oncology, McMaster University, Hamilton, Ontario, Canada. Electronic address: ., Ontario Clinical Oncology Group, Juravinski Hospital, Hamilton, Ontario, Canada., Department of Anaesthesia, McMaster University, Hamilton, Ontario, Canada., Department of Urology, St. Joseph's Health Centre, Hamilton, Ontario, Canada., Department of Oncology, McMaster University, Hamilton, Ontario, Canada; Ontario Clinical Oncology Group, Juravinski Hospital, Hamilton, Ontario, Canada., Department of Oncology, Memorial University, St. John's, Newfoundland, Canada.

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