This retrospective study evaluates the effectiveness of radiotherapy, both external beam and external beam plus brachytherapy. It shows fairly positive results for very high risk cases, comprising any 2 of the 3 criteria: PSA level >20 ng/ml, a Gleason score of 8 to 10, or a clinical stage of T3/T4 disease.
prostatecancerinfolink.net/2014/03/12/modern-5-year-outcome-data-after-radiotherapy-for-very-high-risk-patients/