The low α/β ratio for prostate cancer: What does the clinical outcome of HDR brachytherapy tell us?

摘要: Abstract Purpose Accumulating evidence demonstrates that prostate cancer has a low α/β ratio. However, several challenging issues have been raised from previous studies, including the biologic equivalence between external beam radiotherapy (EBRT) and brachytherapy, effect of relative effectiveness (RBE) for permanent implantation, systematic uncertainties multi-institutional multi-modality clinical data. The purpose this study is to address these by reexamining reported outcome high-dose-rate (HDR) brachytherapy confirm ratio cancer. Methods materials generalized linear-quadratic (LQ) model with considerations sublethal damage repair clonogen repopulation was used calculate cell-killing efficiency treatments Standard models tumor cure based on Poisson statistics were bridge cell killing treatment outcome. data collected in trial using EBRT plus HDR boost at William Beaumont Hospital (WBH) reanalyzed. A 4-year post-treatment time endpoint chosen as compared 3-year because better maturity stability least chi-square method employed fit estimate LQ parameters well their confidence intervals. number clonogens tumors derived separate constraint modeling improve level. Results Our analysis only relationships among parameters, not definitive unique values, can be WBH set alone. This due large statistical uncertainties, i.e., small numbers sampled patients. By combining results obtained Memorial Sloan-Kettering Cancer Center (MSKCC), new (α = 0.14 ± 0.05 Gy −1 , 3.1 −1.6 +2.6 Gy) current without dealing implants. are consistent implants consideration repopulation. provides interpretation currently available Conclusions further support about Gy. shows RBE implantation may clinically significant consistency found supports general opens door search more effective radiotherapeutic approaches cancer, e.g., hypofractionation radiotherapy.