A Phase I/II Trial of Brief Androgen Suppression and Stereotactic Radiotherapy (FASTR) for High Risk Prostate Cancer

Purpose : A Phase I/II trial was initiated to examine the tolerability of a condensed combined modality protocol for high-risk prostate cancer. Materials and Methods : Men scoring > 3 on the Vulnerable Elderly Scale (VES) or refusing conventionally fractionated treatment for high-risk prostate cancer were eligible to participate. Androgen suppression was delivered for 12 months and radiotherapy was delivered using 25Gy to pelvic nodes delivered synchronously with 40Gy fractions to the prostate given as one fraction per week over 5 weeks. The phase I component included predetermined stopping rules based on 6 month treatment related toxicity with trial suspension specified if there were >6/15 patients (40%) or >3/15 (20%) who experienced grade >2 or >3 GI or GU toxicity respectively. Results : Sixteen men were enrolled with seven men meeting the criteria of VES > 3, and nine men having a VES<3 but choosing the condensed treatment. One man was not treated, due to discovery of a synchronous primary rectal cancer. Four patients (26%) experienced ≥ grade 2 toxicity at 6 weeks post treatment. There were 9/15 (60%) who experienced ≥ grade 2 GI or GU toxicity and 4/15 (26%) > grade 3 GI or GU toxicity at 6 months and 5/15 (30%) > grade 2 GI and GU toxicity at 6 months. A review of the 15 cases did not identify any remedial changes thus the Phase I criteria were not met. Conclusion : This novel condensed treatment had higher than anticipated late toxicities, and was terminated before phase II accrual. Treatment factors such as inclusion of pelvic lymph node radiotherapy, planning constraints and treatment margins or patient factors related to the specific frail elderly population may be contributing.

http://www.redjournal.org/article/S0360-3016(15)00252-7/abstract

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