Predictive models in external beam radiotherapy for clinically localized prostate cancer

Predictive models are increasingly being used in effort to allow Physician and patient expectations to be aligned with outcomes that are based on available data. Most predictive models for men treated with external beam radiotherapy for clinically localized prostate cancer are based on Gleason Score, clinical T-Stage and prostate specific antigen (PSA) levels. More sophisticated models have also been developed that incorporate treatment related variables such as the dose of radiation and use of androgen deprivation therapy. Most of the predictive models applied to prostate cancer were derived using PSA recurrence rates as the major endpoint but increasingly clinical endpoints have been incorporated into predictive models. Biomarkers are also increasingly being added to predictive models in an effort to strengthen them. The Radiation Therapy Oncology Group (RTOG) have completed studies on a wide range of markers using tissue from two Phase III Trials (RTOG 8610 and 9202). To date preliminary assessments of p53, DNA Ploidy, p16/pRB, Ki-67, MDM2, Bcl-2/Bax, CAG repeats, Cox-2, Stat3, Cyp3A4 and PKA have been completed. Although not ready for wide spread routine use, there are reasons to believe that future models will combine these markers with traditional pretreatment and treatment related variables and improve our ability to predict outcome and select the optimal treatment